Rmd Cnfg Singleran TX Shr

LTE Radio Access, Rel. RL40, Operating Documention

Recommended Configurations for SingleRAN Transport Sharing

DN09123915 Issue 03 Approval Date 2013-01-23

Confidential

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The information in this document is subject to change without notice and describes only the product defined in the introduction of this documentation. This document is intended for t he use of Nokia Siemens Networks customers only for the purposes of the agreement under which the document is submitted, and no part of it may be used, reproduced, modified or transmitted in any form or means without the prior written permission of Nokia Siemens Networks. The document has been prepared to be used by professional and properly trained personnel, and the customer assumes full responsibility when using it. Nokia Siemens Networks welcomes customer comments as part of the process of continuous development and improvement of the documentation. The information or statements given in this document concerning the suitability, capacity, or performance of the mentioned hardware or software products are given “as is” and all liability arising in connection with such hardware or software software products shall be defined conclusively in a separate agreement between Nokia Siemens Networks and the c ustomer. However, Nokia Siemens Networks has made all reasonable efforts to ensure that the instructions contained in the document are adequate and free of material errors and omissions. Nokia Siemens Networks will, if deemed necessary by Nokia Siemens Networks, explain issues which may not be covered by the document. Nokia Siemens Networks will correct errors in the document as soon as possible. I N NO EVENT WILL NOKIA SIEMENS NETWORKS BE LIABLE FOR ERRORS IN THIS DOCUMENT DOCUMENT OR FOR ANY DAMAGES, INCLUDING INCLUDING BUT NOT LIMITED LIMITED TO SPECIAL, DIRECT, DIRECT, INDIRECT, INCIDENTAL OR CONSEQUENTIAL OR ANY MONETARY LOSSES,SUCH AS BUT NOT LIMITED TO LOSS OF PROFIT, REVENUE, BUSINESS INTERRUPTION, INTERRUPTION, BUSINESS OPPORTUNITY OR DATA,THAT MAY ARISE FROM THE USE OF THIS DOCUMENT OR THE INFORMATION IN IT This document and the product it describes are considered protected by copyrights and other intellectual property rights according to the applicable laws. Wave logo is a trademark of Nokia Siemens Networks Oy. Nokia is a registered trademark of Nokia Corporation. Siemens is a registered trademark of Siemens AG. Other product names mentioned in this document may be trademarks of their respective owners, and they are mentioned for identification purposes only. Copyright © Nokia Siemens Networks 2013. All rights reserved.

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© Nokia Siemens Networks Confidential

DN09123915 Issue 03

The information in this document is subject to change without notice and describes only the product defined in the introduction of this documentation. This document is intended for t he use of Nokia Siemens Networks customers only for the purposes of the agreement under which the document is submitted, and no part of it may be used, reproduced, modified or transmitted in any form or means without the prior written permission of Nokia Siemens Networks. The document has been prepared to be used by professional and properly trained personnel, and the customer assumes full responsibility when using it. Nokia Siemens Networks welcomes customer comments as part of the process of continuous development and improvement of the documentation. The information or statements given in this document concerning the suitability, capacity, or performance of the mentioned hardware or software products are given “as is” and all liability arising in connection with such hardware or software software products shall be defined conclusively in a separate agreement between Nokia Siemens Networks and the c ustomer. However, Nokia Siemens Networks has made all reasonable efforts to ensure that the instructions contained in the document are adequate and free of material errors and omissions. Nokia Siemens Networks will, if deemed necessary by Nokia Siemens Networks, explain issues which may not be covered by the document. Nokia Siemens Networks will correct errors in the document as soon as possible. I N NO EVENT WILL NOKIA SIEMENS NETWORKS BE LIABLE FOR ERRORS IN THIS DOCUMENT DOCUMENT OR FOR ANY DAMAGES, INCLUDING INCLUDING BUT NOT LIMITED LIMITED TO SPECIAL, DIRECT, DIRECT, INDIRECT, INCIDENTAL OR CONSEQUENTIAL OR ANY MONETARY LOSSES,SUCH AS BUT NOT LIMITED TO LOSS OF PROFIT, REVENUE, BUSINESS INTERRUPTION, INTERRUPTION, BUSINESS OPPORTUNITY OR DATA,THAT MAY ARISE FROM THE USE OF THIS DOCUMENT OR THE INFORMATION IN IT This document and the product it describes are considered protected by copyrights and other intellectual property rights according to the applicable laws. Wave logo is a trademark of Nokia Siemens Networks Oy. Nokia is a registered trademark of Nokia Corporation. Siemens is a registered trademark of Siemens AG. Other product names mentioned in this document may be trademarks of their respective owners, and they are mentioned for identification purposes only. Copyright © Nokia Siemens Networks 2013. All rights reserved.

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Recommended Configuration for SingleRAN Transport Sharing

Table of contents This document has 72 pages. Summary of changes ...................................................................... ...................................................................................................... ................................ 6 List of figures ............................................................ ................................................................................................................... ....................................................... 7 List of tables ............................................................. .................................................................................................................... ....................................................... 8 1 Introduction ............................................................ ....................................................................................................... ........................................... 9 1.1 Purpose ................................................................. ............................................................................................................ ........................................... 9 1.2 Overview on the network reference configuration ............................................ 9 1.3 Release information ......................................................... ......................................................................................... ................................ 9 1.4 Feature interdependencies overview ............................................................... 9 1.4.1 GSM .......................................................... ................................................................................................................. ....................................................... 9 1.4.2 WCDMA ................................................................ ......................................................................................................... ......................................... 10 1.4.3 LTE ............................................................ ................................................................................................................. ..................................................... 11 1.5 Input traffic models ........................................................... ......................................................................................... .............................. 12 1.5.1 GSM .......................................................... ............................................................................................................... ..................................................... 12 1.5.2 WCDMA ................................................................ ......................................................................................................... ......................................... 12 1.5.3 LTE ............................................................ ................................................................................................................. ..................................................... 15 2 Common aspects ............................................................. ........................................................................................... .............................. 16 2.1 Hardware ............................................................... ........................................................................................................ ......................................... 16 2.1.1 Base Transceiver Station ............................................................ ............................................................................... ................... 16 2.1.2 Radio controllers .............................................................. ............................................................................................ .............................. 16 2.1.3 Miscellaneous................................................................... ................................................................................................. .............................. 16 2.2 IP-based BTS connection ........................................................... .............................................................................. ................... 17 2.2.1 GSM Packet Abis ............................................................. ........................................................................................... .............................. 17 2.2.2 WCDMA IP-based Iub .................................................................... .................................................................................... ................ 17 2.2.3 LTE IP-based S1/X2....................................................................................... 17 2.3 Mobile Backhaul Network ............................................................ ............................................................................... ................... 17 2.4 Quality of Service ............................................................. ........................................................................................... .............................. 20 2.4.1 Traffic Marking with DSCP .......................................................... ............................................................................. ................... 21 2.4.1.1 DSCP marking for GSM .............................................................. ................................................................................. ................... 22 2.4.1.2 DSCP marking for WCDMA ........................................................ ........................................................................... ................... 22 2.4.1.3 DSCP marking for LTE................................................................... ................................................................................... ................ 23 2.4.2 Traffic Marking with PCP ............................................................. ................................................................................ ................... 24 2.4.3 Ingress Rate Limiting in BTS internal switch .................................................. 24 2.4.4 Uplink Shaping and Scheduling ............................................................. ..................................................................... ........ 25 2.4.5 Controlling Downlink Traffic ........................................................ ........................................................................... ................... 26 2.5 Congestion Control Mechanisms ........................................................... ................................................................... ........ 26 2.5.1 Packet Abis Congestion Control ............................................................ .................................................................... ........ 26 2.5.2 WCDMA internal flow control .................................................................... ......................................................................... ..... 28 2.5.3 HSDPA congestion control .......................................................... ............................................................................. ................... 28 2.5.4 HSUPA congestion control .......................................................... ............................................................................. ................... 29 2.5.5 TCP congestion control for LTE ............................................................. ..................................................................... ........ 30 2.6 RF sharing ............................................................. ...................................................................................................... ......................................... 30 2.7 Physical connectivity at BTS site ........................................................... ................................................................... ........ 30 2.8 Synchronization on BTS site ..................................................................... .......................................................................... ..... 30 2.9 IP addressing ................................................................... ................................................................................................. .............................. 31 2.9.1 VLAN usage at BTS site ............................................................. ................................................................................ ................... 31 2.9.2 Routing configuration in MBH ................................................................... ........................................................................ ..... 31 2.9.2.1 Routing configuration with BFD-triggered static routes .................................. 31 2.9.2.2 Routing configuration with HSRP/VRRP ........................................................ 34 2.9.3 IP address for SSE ........................................................... ......................................................................................... .............................. 36

2.9.4 2.10 2.11 2.12 2.12.1 2.12.1.1 2.12.1.2 2.12.1.3 3 3.1 3.1.1 3.1.2 3.1.2.1 3.1.2.2 3.2 3.2.1 3.2.2 3.2.3 3.2.4 3.2.5 3.2.6 3.2.7 3.2.8 4 4.1 4.1.1 4.1.2 4.1.2.1 4.1.2.2 4.2 4.2.1 4.2.2 4.2.3 4.2.4 4.2.5 4.2.6 4.2.7 4.2.8 4.2.9 5 5.1 5.1.1 5.1.2 5.1.2.1 5.1.2.2 5.2 5.2.1 5.2.2 5.2.3 5.2.4 5.2.5 5.2.6 5.2.7

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Controller site ................................................................................................. 36 Traffic Aggregation on BTS site ..................................................................... 37 Security .......................................................................................................... 38 Auto-configuration .......................................................................................... 38 Measurements ................................................................................................ 38 GSM measurements ...................................................................................... 38 WCDMA measurements................................................................................. 39 LTE measurements ........................................................................................ 39 GSM and WCDMA ......................................................................................... 41 Recommended network configuration description ......................................... 41 General configuration ..................................................................................... 41 Feature usage ................................................................................................ 43 GSM ............................................................................................................... 43 WCDMA ......................................................................................................... 43 RAN parameters for the configuration ............................................................ 44 General ........................................................................................................... 44 Shaping .......................................................................................................... 44 Synchronization .............................................................................................. 47 BTS site 1 (standalone site) ........................................................................... 48 BTS site 2 (hub site) ....................................................................................... 48 BTS site 3 (leaf site) ....................................................................................... 49 BTS IP configuration ...................................................................................... 49 Controller site ................................................................................................. 49 GSM and LTE ................................................................................................. 50 Recommended Network Configuration Description ....................................... 50 General configuration ..................................................................................... 50 Feature usage ................................................................................................ 51 GSM ............................................................................................................... 51 LTE ................................................................................................................. 52 RAN parameters for the configuration ............................................................ 52 General ........................................................................................................... 52 Shaping .......................................................................................................... 52 VLAN Filtering ................................................................................................ 54 Synchronization .............................................................................................. 55 BTS site 1 (standalone site) ........................................................................... 55 BTS site 2 (hub site) ....................................................................................... 56 BTS site 3 (leaf site) ....................................................................................... 57 BTS IP configuration ...................................................................................... 57 Controller site ................................................................................................. 58 WCDMA and LTE ........................................................................................... 59 Recommended Network Configuration Description ....................................... 59 General configuration ..................................................................................... 59 Feature usage ................................................................................................ 61 WCDMA ......................................................................................................... 61 LTE ................................................................................................................. 61 RAN parameters for the configuration ............................................................ 62 General ........................................................................................................... 62 Shaping .......................................................................................................... 62 VLAN Filtering ................................................................................................ 63 Synchronization .............................................................................................. 64 BTS site 1 (standalone site) ........................................................................... 65 BTS site 2 (hub site) ....................................................................................... 66 BTS site 3 (leaf site) ....................................................................................... 68


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5.2.8 5.2.9 6

BTS IP configuration ...................................................................................... 68 Controller site ................................................................................................. 68 Other notes ..................................................................................................... 72

Summary of changes Changes between document issues are cumulative. Therefore, the latest document issue contains all changes made to previous issues. Changes between issues 02 (2013-01-10, WCDMA RAN, RU40) and 03 (2013-01-23, LTE Radio Access, RL40) • Editorial revisions.

Changes between issues 01C (2013-01-10, WCDMA RAN, RU30) and 02 (2013-01-10, WCDMA RAN, RU40) • Editorial revisions.

Changes between issues 01B (2013-01-10, LTE Radio Access RL30) and 01C (2013-01-10, WCDMA RAN, RU30) • Editorial revisions.

Changes between issues 01A (2012-11-23, WCDMA RAN RU30) and 01B (2013-01-15, LTE Radio Access, RL30) • Table 40: VLAN filtering in WCDMA+LTE configuration has been updated

• Chapter 5.2.3: VLAN filtering has been updated. • Editorial revisions. Changes between issues 01 (2012-08-14, WCDMA RAN RU30) and 01A (2012-11-23, WCDMA RAN RU30) • I-HSPA rebranding.

• Editorial revisions.

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List of figures Figure 1: Logical model of Ethernet service ................................................................ 18 Figure 2: Common MBH topology ............................................................................... 20 Figure 3: Shaping functionalities in BTS ..................................................................... 25 Figure 4: Routing configuration for BFD-triggered static routes.................................. 32 Figure 5: Routing configuration for HSRP ................................................................... 34 Figure 6: Accedian Metronode as measurement device for LTE ................................ 40 Figure 7: Several Ethernet services with single performance class ........................... 42 Figure 8: Shaping for GSM and WCDMA ................................................................... 46 Figure 9: Synchronization overview for GSM and WCDMA co-location ..................... 47 Figure 10: GSM + W CDMA BTS site 1 (standalone site) ........................................... 48 Figure 11: GSM + WCDMA BTS site 2 (hub site) ....................................................... 49 Figure 12: Two Ethernet services with single performance class ............................... 51 Figure 13: Shaping for GSM + LTE configuration ....................................................... 54 Figure 14: VLAN IDs used in GSM+LTE configuration ............................................... 54 Figure 15: GSM and LTE synchronization .................................................................. 55 Figure 16: GSM + LTE BTS site 1 (standalone site)configuration .............................. 56 Figure 17: GSM+LTE BTS site 2 (hub site) ................................................................ 56 Figure 18: GSM+LTE BTS site 3 (leaf site) ................................................................. 57 Figure 19: Several Ethernet services with single performance class ......................... 60 Figure 20: Shaping for W CDMA + LTE configuration ................................................. 63 Figure 21: VLAN IDs used in W CDMA+LTE configuration ......................................... 64 Figure 22: Synchronization overview for W CDMA and LTE co-location ..................... 65 Figure 23: WCDMA + LTE BTS site 1 (standalone site) ............................................. 65 Figure 24: WCDMA + LTE BTS site 2 (hub site) ......................................................... 66 Figure 25: WCDMA + LTE BTS site 3 (leaf site) ......................................................... 68

List of tables Table 1: Average traffic per GSM BTS ........................................................................ 12 Table 2: Average user traffic per W CDMA BTS .......................................................... 13 Table 3: Traffic demand on Iub per single BTS .......................................................... 14 Table 4: LTE traffic model ........................................................................................... 15 Table 5: BTS transport interfaces ............................................................................... 16 Table 6: GSM multiplexing .......................................................................................... 17 Table 7: Attributes of performance classes ................................................................. 19 Table 8: RAT service classes to TA/FC/DSCP mapping ............................................ 22 Table 9: DSCP marking for GSM ................................................................................ 22 Table 10: DSCP marking for WCDMA user plane ...................................................... 23 Table 11: DSCP marking for WCDMA non-user plane t raffic ..................................... 23 Table 12: DSCP mark ing for LTE ................................................................................ 24 Table 13: PCP marking ............................................................................................... 24 Table 14: 1SP+5W FQ scheduler ................................................................................ 25 Table 15: Packet Abis Congestion Control Parameters .............................................. 27 Table 16: Queue weights in RNC ................................................................................ 28 Table 17: WCDMA SPI definitions .............................................................................. 29 Table 18: HSUPA congestion control threshold parameters ...................................... 29 Table 19: Synchronization roles for RF sharing .......................................................... 30 Table 20: Static route configuration for downlink traffic .............................................. 33 Table 21: WCDMA BTS uplink route configuration ..................................................... 33 Table 22: WCDMA BTS BFD session parameters ..................................................... 34 Table 23: VLAN and IP address overview .................................................................. 35 Table 24: HSRP configuration ..................................................................................... 36 Table 25: VLAN IDs..................................................................................................... 38 Table 26: W CDMA IP measurements ......................................................................... 39 Table 27: LTE IP measurements ................................................................................ 40 Table 28: GSM and WCDMA traffic amount ............................................................... 43 Table 29: GSM / WCDMA information rates ............................................................... 43 Table 30: IP based route configuration ....................................................................... 45 Table 31: GSM BTS uplink shaping parameters ......................................................... 45 Table 32: WCDMA BTS uplink shaping parameters ................................................... 46 Table 33: GSM BTS as IEEE1588 slave ..................................................................... 47 Table 34: W CDMA BTS as SyncE slave ..................................................................... 48 Table 35: LTE BTS uplink shaping parameters .......................................................... 53 Table 36: VLAN filtering in GSM+LTE configuration ................................................... 55 Table 37: LTE and W CDMA traffic amount ................................................................. 60 Table 38: WCDMA+LTE information rates .................................................................. 61 Table 39: Uplink shaping for WCDMA and LTE configuration .................................... 63 Table 40: VLAN filtering in W CDMA+LTE configuration ............................................. 64 Table 41: WCDMA BTS as IEEE1588 slave and Master on E1 ................................. 66 Table 42: WCDMA BTS as IEEE1588 slave and SyncE master ................................ 67

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1 1.1

Introduction Purpose The GSM, WCDMA, and LTE transport features allow different configurations, suitable to deploy mobile networks of different radio technologies over the same transport network. This document intended for network planners provides guidance configuring the transport features of GSM, WCDMA and LTE radio network systems for representative transport network configurations. This release of Recommended Configurations for SingleRAN Transport Sharing defines recommended transport network configurations for logical GSM Packet Abis, WCDMA IP Iub, and LTE S1/X2 interfaces. The traffic of co-located BTS is aggregated using BTS internal Ethernet switching. The feature set and related parameters are chosen as representative for the considered software releases. Reference configurations of the individual radio access technologies are still valid for single radio technology deployments described in the following documents: Configuring WCDMA RAN and Flexi Direct Transport and Configuring LTE Transport . Disclaimer : System verification of the configurations is ongoing and could require updates in Recommended Configurations for SingleRAN Transport Sharing .

1.2

Overview on the network reference configuration This document describes three combinations of radio technologies namely GSM+WCDMA, GSM+LTE, and WCDMA+LTE, each deployed over an IP/Ethernet backhaul network. Use IP/Ethernet backhaul that is neither CESoPSN nor any other kind of pseudo wire. In the GSM+LTE combination, RF sharing (BSS21520, LTE447) is used exemplarily. In the other radio technology combinations, RF sharing is not used as this is not a mandatory feature.

1.3

Release information This version of the document is based on the following system releases:

1.4



GSM: RG20EP2



WCDMA: RU30EP1



LTE: RL30

Feature interdependencies overview In reference configuration, some features have a direct impact on a shared transport deployment, like Ethernet switching. Other features have a more indirect impact such as telecom features that provide specific traffic types. These are listed separately per radio technology.

1.4.1

GSM The GSM transport related features are: 

BSS101417 QoS aware Ethernet Switching



BSS101459 Full GE support for FIYB/FIQB



BSS21439 Packet Abis Sync. ToP IEEE1588v2



BSS21445 Packet Abis Congestion Reaction



BSS21454 Packet Abis over Ethernet



BSS21502 Cisco 76xx as Flexi BSC site router



BSS30395 Packet Abis Delay Measurement



BSS30450 Packet Abis Synchronous Ethernet

Other features used in the reference configurations:

1.4.2



BSS09006 GPRS System Feature Description



BSS10091 EDGE System Feature Description



BSS21520 RF Sharing GSM-LTE

WCDMA The WCDMA transport related features are: 

RAN74 IP-based Iub



RAN1016 Flexi BTS Multimode System Module



RAN1155 Flexi WCDMA BTS Eth+E1/T1/JT1 Sub-Module 'FTIB' with Timing over Packet



RAN1159 IP Address & Port based Filtering for BTS LMPs



RAN1254 Timing over Packet for BTS Application SW



RAN1708 BTS Synchronous Ethernet



RAN1709 VLAN traffic differentiation



RAN1749 BTS Firewall



RAN1769 QoS aware Ethernet switching



RAN1819 Transport sub-module FTLB for Flexi Multimode BTS



RAN1848 Flexi BTS Multimode System Module - FSME



RAN1884 Cisco 76xx as RNC Site Router



RAN1886 Efficient Transport for small IP packets



RAN1900 IP Transport Network Measurement



RAN2071 Synchronous Ethernet Generation



RAN2382 Flexi BTS Multimode System Module - FSMC



RAN2440 Fast IP Rerouting

1

Other features used in the reference configurations: 

RAN992 HSUPA Congestion Control



RAN1004 Streaming QoS for HSPA (streaming over HSPA)



RAN1110 HSDPA Congestion Control



RAN1201 Fractional DPCH (SRB over HSPA)

1

RAN2071 Synchronous Ethernet Generation uses the same license key as RAN1708 BTS Synchronous Ethernet

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1.4.3



RAN1262 QoS aware HSPA scheduling (streaming over HSPA)



RAN1298 BTS Auto Connection



RAN1299 BTS Auto Configuration



RAN1470 HSUPA 2ms TTI (SRB over HSPA)



RAN1638 Flexible RLC (DL)



RAN1643 HSDPA 64QAM (21.1Mbps peak rate)



RAN1645 HSUPA 16QAM (11.5Mbps peak rate)



RAN1906 Dual-Cell HSDPA 42Mbps (together with RAN1643)



RAN1910 Flexible RLC in uplink



RAN1912 MIMO 42 Mbps



RAN2067 LTE Interworking



RAN2123 Flexi BTS Gigabit Baseband

LTE The LTE transport related features are as follows: 

LTE74 Flexi System Module FSMD



LTE82 High Capacity Flexi System Module FSME



LTE118 Fast Ethernet (FE) / Gigabit Ethernet (GE) electrical interface



LTE119 Gigabit Ethernet (GE) optical interface



LTE129 Traffic prioritization on Ethernet layer



LTE131 Traffic prioritization on IP layer (Diffserv)



LTE132 VLAN based traffic differentiation



LTE134 Timing over Packet



LTE138 Traffic shaping (UL)



LTE144 Transport admission control



LTE504 Cisco76xx as Edge Router and Security Gateway



LTE574 IP Transport Network Measurement



LTE592 Link Supervision with BFD



LTE649 QoS aware Ethernet switching



LTE664 LTE transport protocol stack



LTE713 Synchronous Ethernet



LTE800 Flexi Transport sub-module FTLB



LTE866 Fast IP Rerouting



LTE871 Transport Support Site Support Equipment



LTE875 Different IP addresses for U/C/M/S-plane

LTE931 Ethernet Jumbo Frames



Other features used in the reference configurations:

1.5



LTE9 Service Differentiation



LTE10 EPS bearers for conversational voice



LTE13 Rate capping



LTE447 SW support for RF sharing GSM-LTE



LTE746 IP based Filtering for BTS Site Support Equipment



LTE905 Non GBR QCI 5, 6, 7, 8 and 9

Input traffic models Backhaul related parameters are based on dimensioning for the default traffic profiles of individual radio technologies. The traffic profiles in real mobile networks differ from each other; the dimensioning is network-specific and will differ from the numbers. It is presumed that BSC capacity is estimated according to BSC EDGE Dimensioning, RG20 and RNC capacity is estimated according to Dimensioning WCDMA RAN document, in Nokia Siemens Networks W CDMA RAN, Rel. RU30 . 2

It is assumed that neither baseband nor air interface capacities of the BTSs are limiting factors. As a consequence, the bottleneck in the network will be the transport capacity.

1.5.1

GSM GSM BTS with 6/6/6 TRX configuration is assumed. According to the default traffic profile, there are 110 Erl per GSM site and a data traffic volume of 225MB during busy hour. Assuming a typical distribution of codecs for voice and data, the resulting traffic volume on the Ethernet layer is shown in Table 1: Average traffic per GSM BTS. Note that these numbers depend on the amount of TRXs and other parameters such as used codecs. Traffic Type

Traffic Volume [kbps]

CS user plane

1500

PS user plane

2100

Control plane

400

Total

4000

Table 1: Average traffic per GSM BTS Management plane traffic is not considered; it is normal that software downloads occur mostly in off-peak hours.

1.5.2

WCDMA The dimensioning of the WCDMA access network is described in Dimensioning WCDMA RAN document, in Nokia Siemens Networks WCDMA RAN, Rel. RU30 . The UTRAN interfaces are dimensioned based on the assumed traffic demand figures as given in Table 2: Average user traffic per WCDMA BTS. The traffic demand is established from the traffic model for RU30, with one major exception; most bandwidth 2

In this document the term BTS is used also for WCDMA NodeB and LTE eNodeB.

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demands for the different traffic types are based on average values, while the bandwidth demand for HSPA interactive/background traffic is based on the peak bandwidth of a single user because this peak bandwidth is larger than the average bandwidth. The following service types are assumed to be supported for the defined transport network configurations: 

RT-DCH (incl. AMR voice, CS64)



NRT DCH (interactive/background traffic over DCH)



HSPA streaming with guaranteed bit rate



HSPA interactive/background with nominal bit rate



HSPA interactive/background without nominal bit rate

HSPA interactive/background traffic with and without nominal bit rate are considered separately because they are distinguished in air interface scheduling, although there is no difference in transport. Service Type (RAB)

Service bit rate on Iub in DL

Average DL traffic per BTS (MBH)

CS AMR 12.2 voice (over DCH) 12.2 kbps

23.9 Erl

CS Voice over HSPA CS 64 UDI Video HSPA Streaming (VoIP) PS I/B64/64 PS I/B 64/128

13.2 kbps 64 kbps GBR: 29.4 kbps 64 kbps 128 kbps

1.5 Erl 0.24 Erl 1.0 Erl 185 kbps 22 kbps

PS I/B 64/384

384 kbps

147 kbps

I/B HSPA

Max. 42.2 Mbps

2500 kbps

Table 2: Average user traffic per WCDMA BTS In general, traffic model values are defined per subscriber. It is assumed that each subscriber is using all accounted services in parallel with the assumed traff ic demand per service. The average traffic values in MBH per BTS are calculated, assuming 1200 subscribers per BTS, as given in Table 2: Average user traffic per WCDMA BTS. Using RAN1004 Streaming QoS for HSPA (and RAN1262 QoS aware HSPA scheduling), voice calls via VoIP are assumed to be mapped to an HS-DSCH/E-DCH bearer with a guaranteed bit rate of 29.4 kbps (using AMR codec). Voice service split between traditional CS AMR Voice, CS Voice over HSPA and VoIP users is assumed as 90:6:4 respectively. The average user traffic demand for PS services relate to the offered traffic in downlink. To reflect the asymmetric nature of PS data services, the following UL/DL asymmetry ratio applies to the offered traffic: 

Release 99 (UL/DL): 1/5.8



HSxPA Rel.6 (HSUPA/HSDPA): 1/3.9

The resulting bandwidth demand per single logical Iub (for the assumed traffic model presented in Table 2: Average user traffic per WCDMA BTS) is calculated using the dimensioning rules given in Dimensioning WCDMA RAN document, in Nokia Siemens Networks WCDMA RAN, Rel. RU30 and presented in Table 3: Traffic demand on Iub

per single BTS. The feature RAN1886 Efficient Transport for Small IP Packets provides an estimated bandwidth gain of 96 kbps on IP level and 263 kbps on Ethernet level. Traffic demand

User plane CAC-committed

Uplink / Downlink

IP layer BW / RNC dimensioning [kbps]

Ethernet layer BW / BTS dimensioning [kbps]

UL

2108

2483

DL

3311

3701

UL

436

507

DL

436

507

UL

56

64

DL

56

64

UL

0

0

DL

10

16

UL

29

36

DL

57

66

UL

2629

3090

DL

3870

4353

User plane non-guaranteed bandwidth traffic

UL

1520

1893

DL

3798

4418

Total guaranteed and nonguaranteed bandwidth traffic

UL

4148

4982

DL

7668

8770

Control plane

Management plane

IEEE1588

CCH

Total guaranteed traffic

bandwidth

Table 3: Traffic demand on Iub per single BTS CCH bandwidth is calculated assuming 3 cells per BTS. Control plane bandwidth is configured symmetrically with the same values for uplink (BTS) and downlink (RNC) direction, based on dominant downlink traffic volume. NOTE The control plane, management plane, IEE1588, and CCh are not subject to CAC algorithm. However, these should be assigned to a pool of guaranteed bandwidth. The last mile bandwidth should be provisioned to allow the full usage of available bandwidth on the radio side (peak rate). According to Dimensioning WCDMA RAN document, in Nokia Siemens Networks WCDMA RAN, Rel. RU30, System Library it is recommended to dimension the last mile link per BTS as a sum of peak HSDPA throughput and non-user plane traffic. Assuming, for example UE cat 24 (42 Mbps in DL) and BLER=10% (peak rate of 39.4 Mbps on IP layer, 40.52 Mbps on Ethernet layer), the amount of HSDPA traffic is 40.52 Mbps + 652.3 7 kbps ≈ 41.2 Mbps on Ethernet layer.

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1.5.3

LTE The average traffic of an LTE BTS that is used in this document is described in LTE Access Dimensioning Guideline, RL 30 . The throughput is derived as the maximum of the average traffic of a 3 cell LTE BTS and the peak capacity of a single cell. The bandwidth per carrier is 10 MHz in this example. The overall user plane traffic is 70 Mbps in downlink, of which 2 Mbps is assumed to be VoIP with QCI-1. Within the timeframe of this document, it is assumed that most voice calls are still handled via GSM and/or WCDMA. The bandwidth requirements on S1 and X2, measured on Ethernet level, are summarized in Table 4: LTE traffic model. The relation between S1 and X2 traffic is not relevant within the scope of this document. Management plane traffic will be on average in the order of 64 kbps. 1000 kbps is provided to support optional tracing. Traffic Type VoIP (QCI1)

Bandwidth [kbps] 2000

User plane without GBR Control plane

68000 1000

IEEE1588 Management plane

16 1000

Total 72016 Table 4: LTE traffic model The user plane traffic in uplink, especially user plane without GBR, is considered to be smaller than in downlink.

2

Common aspects This section describes features and functionalities used in several network reference configurations. Multiple BTS are deployed on a single site, using the functionalities provided by the BTS. No dedicated cell site gateways are required. The BTS aggregating the traffic also implements the synchronization hub. To increase availability of the voice service as much as possible, the BTS of the radio technology with majority of voice traffic is used as hub BTS, exceptions are RF-sharing where selection of hub BTS is driven by requirements for clock source. On the radio controller sites, site solutions are used as defined for the different radio technologies.

2.1 2.1.1

Hardware Base Transceiver Station Flexi Multiradio BTSs are used for each radio technology. The system modules for GSM BTS are ESMB or ESMC; FSMC, FSMD, or FSME for WCDMA BTS, and FSMD or FSME system modules for LTE BTS. These variants differ in capacity but are functionally equivalent from a transport point of view The BTS provides the transport interfaces as listed in Table 5: BTS transport interfaces. Note: FTIB is not used for LTE BTS in the network configurations in this document. Transport Module

Radio Technology

Transport Interfaces

Comments

FIQB

GSM

2x1000Base-T, 1x1000Base-X 4xE1/T1

1000Base-T requires the feature BSS101459 Full GE support for FIYB/FIQB. 3 Ethernet interfaces can be used simultaneously

FTIB

WCDMA

2x1000Base-T, 1x1000Base-X, 4xE1/T1/JT1

2/3 physical Ethernet interfaces can be used simultaneously, any combination is possible

FTLB

WCDMA, LTE

2x1000Base-T, 1x1000Base-X, 4xE1/T1/JT1

3 Ethernet interfaces can be used simultaneously

Table 5: BTS transport interfaces

2.1.2

Radio controllers Radio controller models for GSM and WCDMA are Flexi BSC and RNC2600, respectively. Multicontroller BSC and RNC are out of the scope of this document.

2.1.3

Miscellaneous Cisco 7609 based controller site solutions are used in this document. For more information, see the following documents: BSC TRANSPORT SITE SOLUTION, RG20 Mother Document, Scenarios and Requirements, BSC TRANSPORT SITE SOLUTION RG20 Daughter Document External L2/L3 Equipment , and RAN1884:

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Cisco 76xx as RNC Site Router, in Nokia Siemens Networks WCDMA RAN, System Library . A single IEEE1588 master is deployed on the controller site. Stand-alone OMS for WCDMA is also used. Whether this is deployed on the controller site or in a remote network operations center is out of the scope of this document. The iOMS for LTE is not expected to be deployed on the controller site. It is assumed to be deployed in some network operations center.

2.2

IP-based BTS connection All recommended configurations in this document are based on IP over Ethernet connectivity for all base stations.

2.2.1

GSM Packet Abis The GSM feature BSS21454: Packet Abis over Ethernet provides the backhaul connectivity for the GSM BTS that is CESoPSN is not used. Several voice user plane IP packets are multiplexed. Corresponding parameters to control the amount of multiplexing are configured as defined in Table 6: GSM multiplexing. User plane traffic for data calls is not multiplexed. Parameter

Value

Comment

8 rtsl

Maximum amount of multiplexing: 8 rtsl = 4.616 ms

4 ms

-

300 bytes

sufficient to multiplex 10 calls

Table 6: GSM multiplexing

2.2.2

WCDMA IP-based Iub RAN74 IP-based Iub is use to connect the WCDMA BTS. In some configurations in this document, the WCDMA voice traffic is carried separately from the HSPA NRT traffic and subject to another bandwidth profile. As such, RAN1886 Efficient Transport for small packets is used to reduce the bandwidth requirements for voice traffic and other user plane traffic with the same DSCP. Default parameter values for controlling the amount of multiplexing are used; that is, in BTS, packets are buffered at most 2ms before sent as multiplex packet and no more than 30 packets are multiplexed together. Packets with the same DSCP as voice are subject to multiplexing, that is DSCP 46, see Table 10: DSCP marking for WCDMA user plane. Note: Load sharing among multiple IP addresses in the RNC is not use. All packets for multiplexing will be exchanged with the same IP addresses at BTS and RNC, allowing the largest possible efficiency gain by multiplexing.

2.2.3

LTE IP-based S1/X2 LTE traffic for both S1 and X2 interfaces is carried over IP/Ethernet.

2.3

Mobile Backhaul Network Multiple RATs are deployed over existing infrastructure. Therefore, the NE configuration has to adapt to this infrastructure. The network reference configurations as described in this document are supported over different types and topologies of transport networks.

Nevertheless, in the different cases some assumptions about the transport network have to be made. In this document, Ethernet services are used as a common abstraction of the network. In case of BTS chains, Ethernet services terminate before the first BTS in the chain. That is the connection between chained BTSs does not belong to an Ethernet service. The connection between chained BTSs could be a microwave link owned and operated by the mobile network owner. The L2 network provides Ethernet connectivity among several attachment points (AP). Each attachment point can be an endpoint of several Ethernet services (ES). Each Ethernet service is identified by one or several VLAN IDs. The Ethernet services that terminate at a single attachment point must be identified by different VLAN IDs. If an Ethernet service terminates at more than 2 attachment points, it corresponds logically to a bridged network. See Figure 1: Logical model of Ethernet service. AP

AP L2 network

corresponds to

AP

AP ES

ES AP

AP

Figure 1: Logical model of Ethernet service An Ethernet service may be provided with different quality guarantees regarding packet delay, packet delay variation, and packet loss rate. Such quality attributes are negotiated between a service provider and service user in a service level agreement (SLA). Ethernet frames within an Ethernet service are treated similarly. Each Ethernet service implements one performance class (PC). Two different performance classes are considered: High and Low. Within the configurations, GSM and LTE uses performance class High, and part of the WCDMA traffic uses performance class Low. Usage of each performance class is explained in the specific configurations. The quality attributes are listed in Table 7: Attributes of performance classes. For the sake of simplicity within this document the most stringent values of all 3 r adio technologies are used as quality attributes for performance class High. Performance class name

Packet delay [ms]

Packet delay variation [ms]

Packet loss rate [%]

IEEE1588

100 ms

5 ms

2%

See Impact of Transport Network Impairments on WCDMA Network Performance

GSM

15 ms

5 ms

0.001%

Most stringent values from document Transport Network Solutions for BSS, RG20

-5

(10 )

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Comment

WCDMA w/o HSPA NRT

10 ms

--

--

HSPA NRT

20 ms

7 ms

0.5%


No more than 10% degradation of KPIs, see in document Impact of Transport Network Impairments on WCDMA

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Performance class name

Packet delay [ms]

Packet delay variation [ms]

Packet loss rate [%]

Comment

Network Performance LTE

20 ms

5 ms

0.00001% -7 (10 )

Most stringent values from Configuring LTE RL20 RAN Transport, RL 30

High

10 ms

5 ms

0.00001% -7 (10 )

Most stringent values of IEEE1588, GSM, WCDMA, and LTE

Low

20 ms

7 ms

0.5%

Same as HSPA NRT

Table 7: Attributes of performance classes The amount of data carried by an Ethernet service is limited by a bandwidth profile enforced at each attachment point of service. Same bandwidth profile is used at each attachment point of an Ethernet service. That is, the Ethernet service provides the same bandwidth in uplink and downlink directions of the mobile backhaul. The bandwidth profile is defined as a peak bandwidth (PBw), guaranteed bandwidth (GBw), and burst size (BS). In this document, the burst size corresponds to 100 ms of traffic with peak bandwidth. As an example, if the peak bandwidth is 20 Mbps, then the burst size is 2 Mbit. The bandwidths can be configured with a granularity of 1Mbps. Guaranteed bandwidth of the Ethernet service is always present, while peak bandwidth is provided only during normal operation. During network failure, peak bandwidth is not available. However it might be possible to provide capacity because of statistical multiplexing. The bandwidth profile is enforced in each attachment point. Traffic exceeding peak bandwidth and burst size is discarded QoS unaware. That is all frames within a given Ethernet service are treated equally independent of their DSCP or PCP marking. The PCP marking is preserved by the Ethernet service. The Ethernet service allows carrying Ethernet jumbo frames up to 2000 bytes; therefore, no IP fragmentation is needed for LTE S1 and X2 traffic because of limitations of the MBH network as long as the end users do not send IP packets larger than 1500 bytes. Note that there might be other reasons causing smaller MTUs and thereby IP fragmentation. Ethernet services terminate at a pair of routers at the controller site. As a consequence, radio controllers and core network elements on one side and BTSs on the other side are in different broadcast domains. There is no direct L2 connection among these types of elements. This pair of routers terminates the MBH network for LTE on one side and the core network for 3 radio technologies on the other side. Each Ethernet service has two attachment points at the controller site. Regarding the BTS, only a single BTS site or a chain of sites are connected to one Ethernet service; therefore, each Ethernet service has three attachment points, two on the controller site and one on the BTS. Network reference configurations comprise three BTS sites. Two of the sites form a short chain. Each site has two co-located BTSs with different radio technologies. Ethernet services are used to connect the BTS sites/chains and the controller site.

The selection for which BTS is used as a hub for another co-located BTS is explained in more detail in the individual configurations. See Figure 2: Common MBH topology using GSM BTS in each site. BTS site 3

WCDMA BTS

BTS site 2

WCDMA BTS

AP

AP GSM BTS

GSM BTS BTS site 1

WCDMA BTS

L2 network

ToP master RNC BSC

A/Iu/S1

GSM BTS

Figure 2: Common MBH topology Each of the radio technologies can provide voice service, but there is one radio technology considered for providing the majority of voice services in each of the configurations in this document. Usually, this radio technology is GSM. In the WCDMA+LTE configuration it is WCDMA. In the configurations, traffic of the main voice service is carried in a dedicated Ethernet service separate from the traffic of the other radio technology. Using separate Ethernet services eases operability and maintainability. The voice service could use an Ethernet service with a higher availability. At least two Ethernet services are used per BTS site or chain. The BTS of the same radio technology in the BTS chain can use the same Ethernet service, increasing statistical multiplexing gain and reducing the number of Ethernet services. GSM and LTE BTS use a single VLAN for user plane traffic. A single Ethernet service is used for user plane traffic of a GSM or LTE BTS. This single Ethernet service has to provide performance class High, satisfying the most stringent requirements. Also, the full bandwidth provides GBw. In contrast, WCDMA BTS allow separating the user plane traffic into two VLANs, allowing two Ethernet services with different performance class. The Ethernet service with performance class Low it is possible to provide less guaranteed bandwidth than the peak bandwidth. CAPEX/OPEX increases with the number of Ethernet services, whereas providing the majority of bandwidth with performance class Low and the ability to provide less guaranteed bandwidth than the peak bandwidth might decrease OPEX. Such traffic separation is used in the GSM+WCDMA configuration.

2.4

Quality of Service The QoS for a connection through transport network is defined by packet delay, packet delay variation, packet loss rate, bandwidth and the availability that the transport network provides. In leased line networks, these characteristics are defined in the SLA. The corresponding configuration and implementation of the SLAs in the L2 cloud is out of scope of this document. Traffic marking via DSCP or PCP is important in network elements outside of the L2 network. In both uplink and downlink directions, traffic has to be shaped to match the policed bandwidth at the attachment point of each Ethernet service. Exceeding the policed bandwidth causes packet drop of arbitrary packets as the ingress policers are

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assumed to operate QoS unaware. Traffic is marked according to type and importance, the shapers and schedulers can make use of this information such that the requirements for the different traffic types are met.

2.4.1

Traffic Marking with DSCP The traffic of the different radio technologies has different requirements for delay and jitter. Different treatment aggregates and forwarding classes are defined f or the different traffic types in Backhaul Sharing QoS Guideline. This document defines a common DSCP marking for all 3 radio technologies considered, see Table 8: RAT service classes to TA/FC/DSCP mapping. Treatment Aggregate

Forwarding Class

Radio Access Technology

Service Class

DSCP (dec)

Network Control

Network Control

LTE

synchronization plane

48

Network Control

Network Control

LTE

Network control plane (BFD)

48

Network Control

Network Control

WCDMA


48

Network Control

Network Control

WCDMA

Network control plane (BFD)

48

Network Control

Network Control

GSM


48

Real-Time

Conversational

GSM

CS voice

46

Real-Time

Conversational

GSM

control plane

46

Real-Time

Conversational

LTE

Conversational voice (QCI-1)

46

Real-Time

Conversational

WCDMA

CS voice (WB-AMR, AMR), CS 46 data (DCH RT)

Real-Time

Conversational

WCDMA

Signaling Radio Bearers (SRB)

Real-Time

Conversational

WCDMA

Common Transport Channels 46 (CTrCH)

Assured Elastic

Streaming

GSM

PS-data

34

Assured Elastic

Streaming

G SM

management plane

34

Assured Elastic

Streaming

WCDMA

control plane

26

Assured Elastic

Streaming

LTE

control plane

26

Assured Elastic

Streaming

LTE

IMS signaling (QCI-5)

26

Assured Elastic

Streaming

WCDMA

PS data (DCH NRT)

26

Assured Elastic

Streaming

WCDMA

HSPA, DCH Streaming

26

Assured Elastic

Streaming

WCDMA

Frame Protocol Control PDUs

26

Elastic

I/B (HSPA)

LTE

management plane

20

Elastic

I/B (HSPA)

WCDMA

management plane

20

Elastic

I/B (HSPA)

WCDMA

HSPA NRT

18

Elastic

I/B

LTE

Video live streaming (QCI-7)

12

Elastic

I/B

LTE

Video buffered streaming (QCI-6)

10

Elastic

I/B

LTE

Premium TCP-based data

0

46

Treatment Aggregate

Forwarding Class


Service Class

DSCP (dec)

(QCI-8) Elastic

I/B

LTE

TCP-based data (QCI-9)

0

Table 8: RAT service classes to TA/FC/DSCP mapping Due to the different congestion control mechanisms for WCDMA HSPA NRT and LTE NRT traffic, the corresponding traffic has to be mapped to separate forwarding classes. For further details, see Backhaul Sharing QoS Guideline.

2.4.1.1

DSCP marking for GSM GSM BTS does not support marking with DSCP 48, therefore uplink synchronization plane traffic of GSM is marked with DSCP 46. DSCP for CS and PS user plane is configured in ETP-E. DSCP for control and management plane is configured in BCSU. The BSC configures the GSM BTSs accordingly; no DSCP marking has to be configured in the GSM BTSs. The corresponding parameters belong to the BSC radio network managed object, see Table 9: DSCP marking for GSM. Parameter

Service class

Value

CS voice

46

PS data

34

Management plane

34

Control plane

46

Synchronization plane

46

Table 9: DSCP marking for GSM CS voice and PS data have to be marked with different DSCPs and mapped to different queues in the BTS, see Backhaul Sharing QoS Guideline. Note that ICMP traffic from BSC as well as from GSM BTS is always marked with DSCP 0.

2.4.1.2

DSCP marking for WCDMA DSCP marking for the user plane is configured in the RNC. The chosen DSCP value for each bearer is signaled to the BTS and does not have to be configured separately in the BTS. The values configured in WBTS objects in the RNC are shown in Table 10: DSCP marking for WCDMA user place. is configured to 0, as the feature RAN1253 Transport QoS is not used. Parameter

Service class

Value 0

CS voice (WB-AMR, AMR), CS data (DCH-RT), common transport channels (CTrCH), Signaling Radio Bearers

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Parameter

Service class

Value

PS data (DCH NRT)

26

HSPA, DCH streaming

26

HSPA NRT

18

Frame Protocol Control PDUs

26 26

Network control (BFD)

48

Table 10: DSCP marking for WCDMA user plane The DSCP for control plane traffic is configured in both the RNC and BTS. The DSCP for management plane traffic can be configured in the BTS only; the RNC always marks this traffic with DSCP 0. It is recommended to perform remarking (to DSCP 20) for this traffic in the edge routers. The DSCP for IEEE1588 can be configured in the BTS and in the IEEE1588 master. The parameters are shown in Table 11: DSCP 11: DSCP marking for WCDMA non-user plane traffic. Parameter

Value

Comment

26

RNC, IPNB object

48

BTS, QoS/trafficTypesMap object

26 20

Table 11: DSCP marking for WCDMA non-user plane traffic

2.4.1.3

DSCP marking for LTE LTE bearers with QCI 2, 3, or 4 are not deployed in this version of the document. DSCP marking for this traffic can be done consistently with Table with Table 8: RAT 8: RAT service classes to TA/FC/DSCP mapping. The DSCP marking for LTE uplink traffic is configured in the LTE BTS for all traffic types. A corresponding marking of downlink traffic is needed in SAE-GW and MME or by the router at the MBH edge. The parameters for the LTE BTS are shown in Table 12: DSCP 12: DSCP marking for LTE. Parameter

Service class

Value

Conversational voice (QCI-1)

46

IMS signaling (QCI-5)

26

Video buffered streaming (QCI-6)

10

Video live streaming (QCI-7)

12

Premium TCP based data (QCI-8)

0

TCP based data (QCI-9)

0

Parameter

Service class Control plane

Value 26 10

Management plane

20

Synchronization plane

48

Network control (BFD)

48

Site Support Equipment, see also Chapter 2.9.3. 2.9.3.

0

Table 12: DSCP marking for LTE

2.4.2

Traffic Marking with PCP The ARP packets are marked with PCP 7 by the BTS of each RAT, this value is not configurable. IP packets are marked in BTSs according to Table to Table 13: PCP 13: PCP marking. _____________________________________ _______________________________________________________________ _____________________________ ___

NOTE In WCDMA BTS, PCP is derived from the PHB, while in GSM and LTE, PCP is derived from the DSCP. Both DSCP 46 and 48 are mapped to the same PCP, which is 5. _____________________________________ ___________________ ______________________________________ ________________________________ ____________

DSCP

PHB

p-bit

ARP

--

7

46, 48

EF

5

34

AF4

4

26, 28

AF3

3

18, 20

AF2

2

10, 12

AF1

1

0

BE

0

Table 13: PCP marking The downlink PCP marking for IP packets is provided by the edge routers according to Table 13: PCP 13: PCP marking.

2.4.3

Ingress Rate Limiting in BTS internal switch The BTS internal switch functionality provides the possibility to limit the ingress rate for each individual port, independent of whether this is used to connect to the mobile backhaul, to a co-located BTS, or to a chained BTS site. The FIQB transport module accepts very small bursts only; therefore the ingress rate limiting functionality of the FIQB will not be used in configurations presented here. BTSs limit their own uplink traffic. The detailed configuration is presented for the specific configurations.

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2.4.4

Uplink Shaping and Scheduling BTS uplink shaping configuration depends on the network configuration. Shaping of egress traffic takes place at two locations in the BTS. First, the BTS ’s own ’s own egress traffic is shaped before it enters the BTS integrated switch. Then, at each physical Ethernet interface, the aggregated egress traffic of the Ethernet switch is shaped.

Shaping Figure 3: Shaping functionalities in BTS Each BTS in the configurations in this document shapes its own egress traffic. The BTS integrated switch is not used in the leaf BTS in the configurations, shaping by the BTS integrated switch is applied in hub BTSs only. All the BTSs use a 1SP + 5W FQ scheduler when shaping its own egress user plane traffic. The DSCP to queue mapping is shown in Table in Table 14: 1SP+5WFQ 14: 1SP+5WFQ scheduler. In the configurations, control and management plane, traffic is handled by the same schedulers. In GSM BTS, the same scheduler is used, whereas in WCDMA and LTE BTS, a separate scheduler is used. The separate scheduler for WCDMA and LTE BTS uses a single FIFO queue. The mappings from DSCP to queues are defined in Backhaul Sharing QoS Guideline. Guideline . Treatment Aggregate

Forwarding Class

DSCP (dec)

Queue

Network Control

Network Control

CS6 (48)

SP

Real-Time

Conversational

EF (46)

Assured Elastic

Streaming

AF41 (34)

WQ1

Assured Elastic

Streaming

AF31 (26)

WQ2

Elastic

I/B (HSPA)

AF22 (20)

WQ3

AF21 (18) Elastic

I/B

AF12 (12)

WQ4

AF11 (10) Elastic

I/B

Table 14: 1SP+5WFQ scheduler

BE (0)

WQ5

The weights for WQ1 and WQ2 must be sufficiently large for the dimensioned amount of traffic. The weights for WQ3, WQ4, and WQ5 should correspond to the targeted bandwidth ratio among the forwarding classes when the link is fully utilized. The weights 1:1:1 are used, providing equal bandwidth to each of the forwarding classes and preventing starvation of any of them. The GSM BTS shapes its aggregated egress traffic per interface, independent of the VLANs used. The WCDMA and LTE BTS can either shape the aggregated egress traffic or the traffic per VLAN. The GSM and WCDMA BTS apply tail drop to each queue. The LTE BTS applies weighted tail drop for the AF PHBs, where packets with higher drop precedence is discarded before packets with lower drop precedence. Shaping of the aggregated traffic is described in Chapter 2.10.

2.4.5

Controlling Downlink Traffic Downlink traffic per GSM BTS can be controlled by using the Packet Abis congestion control functionality, see Chapter 2.5.1: Packet Abis Congestion Control. Downlink shaping per IP-based route in the RNC is based on internal flow control (IFC), see Chapter 2.5.2: WCDMA internal flow control. Although an LTE SAE-GW can shape the traffic of a single bearer, it cannot shape the aggregate traffic of one LTE BTS. Note that several SAE-GWs as well as neighboring LTE BTSs might send traffic towards a single LTE BTS. Where necessary, downlink shaping for LTE is provided by the edge routers. Downlink shaping and scheduling in the edge routers is configured similarly as the uplink shaping and scheduling in the BTSs For mapping of DSCPs to queues and for queue weights see Table 14: 1SP+5WFQ scheduler. The shaping rates are described in the specific configurations.

2.5

Congestion Control Mechanisms The radio technologies have different mechanisms to react on congestion and to control the resulting amount of traffic.

2.5.1

Packet Abis Congestion Control Different codecs can be applied for different GSM calls. Packet Abis congestion control monitors throughput and detects packet loss and in turn, reduces the amount of traffic sent. Packet Abis congestion detection is applied in the BTS separately for both uplink and downlink traffic. The observed congestion status is signaled from the BTS to the BSC, which reduces codec rates and the bandwidth of data calls if needed. The threshold parameters define when congestion or a severe congestion is detected, as well as the durations of the congestion has to be present or absent before the BTS triggers action. The packet drop period values indicate how long the corresponding uplink packets may be buffered in the BTS. In case they are buffered for a longer period, they will already be discarded in the BTS, as they would arrive too late in the BSC and would likewise be discarded there. Parameter

abbrevi ation

Object BCF

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Value

Comment

enabled

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Parameter

abbrevi ation

Object

Value

Comment

BCF BCF

5000 kbps

guaranteed bandwidth of corresponding Ethernet service

BCF

1522 bytes

BCF

5000 kbps

BCF

92%

BCF

97%

BCF

5

5*10E-4

BCF

19

10*10E-3

BSC

4 sec

4 sec of congestion before declaring congestion

BSC

10 sec

10 sec without congestion before declaring end of congestion

BSC

10 sec

10 sec of packet loss before declaring this

BSC

100 sec

100 sec without packet loss before declaring this

BSC

25 ms

BSC

25 ms

BSC

0 ms

BSC

0 ms

guaranteed bandwidth of corresponding Ethernet service

Infinite period, no such traffic is discarded

Table 15: Packet Abis Congestion Control Parameters

The capacity of the Ethernet services is provided in integer multiples of 1 Mbps. There is some spare bandwidth available for GSM traffic in the configurations in this document. The uplink committed information rate is set to the guaranteed bandwidth of the corresponding Ethernet service. This provides a hard limit for GSM traffic. The parameter BU1 is set to a value of 92%, such that GSM congestion control starts when the dimensioned traffic amount is exceeded, that is about 4.6 Mbps. BU2 is set to 98%, trying to reduce the GSM traffic volume more severely before reaching the hard limit enforced by the BTS scheduler in uplink and the Ethernet service policer in downlink.

2.5.2

WCDMA internal flow control Internal flow control (IFC) can be used to limit downlink user plane traffic in the RNC. The RNC limits the traffic to the committed bitrates of the IP based routes (97% of that, minus committed signaling and DCN bitrat es). QoS is considered, which allows prioritizing traffic types, such as voice traffic over DCH NRT traffic. Note that control plane and management plane traffic are not shaped by this functionality, nor are their traffic volumes considered. Voice and other RT DCH calls, as well as signaling radio bearers are not shaped either, but their traffic volumes are used by IFC to limit the NRT calls. IFC is used for both high-priority and low-priority user plane. IFC can be used to shape the NRT user plane traffic against known static bandwidth limitations, but it cannot cope with bandwidth variations in the backhaul networks. Hence, IFC is used to shape against the peak bandwidth of an Ethernet service. If the guaranteed bandwidth of an Ethernet service is smaller than the peak bandwidth, then additional mechanisms, such as HSPA CC are needed to cope with this variable bandwidth. Besides the bandwidths, the most relevant parameters for IFC are the mapping of DSCP to queues and the corresponding queue weights. The relevant DSCPs are 46 for voice, common channels, and SRBs, whereas 26 is used for the remaining highpriority user plane traffic such as DCH NRT. HSPA NRT traffic is marked with DSCP 18. The default queue weights as shown in Table 16: Queue weights in RNC can be used. DSCP

PHB

Queue weight

46

EF

Strict priority

34

AF4

60

26

AF3

25

18

AF2

10

10

AF1

4

0

BE

1

Comment

Not used

Not used

Table 16: Queue weights in RNC

2.5.3

HSDPA congestion control The WCDMA features RAN1004 Streaming QoS for HSPA, RAN1201 Fractional DPCH, and RAN1689 CS voice over HSPA require the feature RAN1262 QoS Aware HSPA Scheduling. The default SPI mappings for this feature in the RNC RNPS object and of the BTSSCW object in the BTS are used, see Table 17: WCDMA SPI definitions. It is assumed that the same THP and ARP settings for each NRT call are used in the core network. Also, the feature Iub Transport QoS (RAN1253) is not applied. Therefore, there is no QoS differentiation. All HSPA NRT calls are marked with DSCP 18, see Table 10: DSCP marking for WCDMA user plane.

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QoSPriorityMapping

QoSPriority (HSPA SPI)

15 14 12 13 13 13 11 7 3 10 6 2 9 5 1 8 4 0 0 Table 17: WCDMA SPI definitions

BTS Scheduling Weight 0 0 40 0 0 0 35 15 6 30 10 5 25 9 2 20 8 1 1

In the downlink direction, HSDPA congestion control is used to adapt the bit rate of the NRT HSPA bearers in case less than peak bandwidth is available in an Ethernet service used for HSDPA NRT. The congestion control policy in the BTS is set to ON for SPIs 0 to 11. For SPIs 12 to 15 the congestion control policy is set to OFF. Congestion control will not be applied to conversational, streaming, nor signaling bearers on HSDPA. The congestion control policy for streaming bearers is set to OFF instead of controlling to GBR, otherwise the average delay of streaming and NRT traffic will be used in the congestion control. However, streaming and NRT traffic are mapped to different PHBs and queues in MBH and are expected to experience much lower delay. The average delay would not provide useful information anymore. HSDPA congestion control is operated with default value for the threshold parameters that is a value of 50 ms for Thmin and 250 ms for Thmax.

2.5.4

HSUPA congestion control HSUPA congestion control is used in uplink with default values, see Table 18: HSUPA congestion threshold parameters. Parameter

Value 50 ms 70 ms 100 ms

Table 18: HSUPA congestion control threshold parameters

2.5.5

TCP congestion control for LTE Congestion of LTE traffic is handled by the end user TCP congestion control. Note that traffic carried via UDP and without congestion control mechanisms will not be affected. There is no subscriber differentiation, bearers with both QCI8 and QCI9 are marked with DSCP 0 and will be mapped to the same queues. Therefore, these packets are treated identically in the transport network.

2.6

RF sharing RF sharing allows using the same RF module for two system modules of different radio technologies. When RF sharing is used, the two system modules are synchronized via RP3-01. No additional synchronization via the transport interfaces must be done. The system module of one specific radio technology is always acting as clock m aster. In Table 19: Synchronization roles for RF sharing, the roles clock slave and clock master are indicated for the different RAT combinations. RAT combination

Clock master

Clock slave

GSM+WCDMA

WCDMA

GSM

GSM+LTE

LTE

GSM

WCDMA+LTE

not supported currently

Table 19: Synchronization roles for RF sharing Although RF sharing provides CAPEX and OPEX redu ctions for a single RAN deployment, it is not a prerequisite from a shared transport perspective. RF sharing will be used exemplarily in this document in the GSM+LTE configuration to show the impact on synchronization. Note that this configuration could also be deployed without RF sharing, and the GSM+WCDMA configuration could also be deployed with RF sharing.

2.7

Physical connectivity at BTS site Optical Ethernet is used to connect the hub BTS on each site to the backhaul network. For co-located BTSs and for chaining another BTS site, electrical Ethernet is used. To keep configurations as homogenous as possible, 1000Base-T is used, even if on some interface 100Base-T would be sufficient regarding the traffic volume. All Ethernet interfaces are configured to detect speed and duplex automatically. GSM BTS is also configured to advertise 1000 Mbps on electrical interfaces.

2.8

Synchronization on BTS site In general, the hub BTS on each site acts as IEEE1588 slave, providing synchronization to a co-located BTS via Synchronous Ethernet (preferred) or via an E1 line without traffic. WCDMA FTIB transport module cannot regenerate Synchronous Ethernet, so an additional E1 line is deployed. Alternatively, a dedicated IEEE1588 slave per BTS can be used. In case RF sharing is used, the synchronization on a BTS site is distributed via the RP3 interface instead of Synchronous Ethernet.

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2.9 2.9.1

IP addressing VLAN usage at BTS site Different IP address ranges are used per RAT; additionally, different VLANs are used per BTS. The management plane is carried on a separate VLAN, whereas user, control, and synchronization plane traffic are carried together on dedicated VLANs for each RAT. In some configurations the WCDMA user plane is split, the high-priority traffic is carried together with control- and synchronization plane, the low-priority traffic is carried separately. Dedicated VLANs are used for each GSM BTS because there is no gain by statistical multiplexing. For other radio technologies, several BTSs can be connected to the same VLANs. Note that for WCDMA, two IP addresses have to be provided in the OAM subnet of the BTS. Therefore, it is not possible to reuse the transport address for management plane as IP address for the management applications. Two different IP subnets are used; one for management plane transport and another one for the BTS OAM subnet providing IP addresses for the management plane applications. For GSM and LTE BTS, it is possible to use the transport address also for the management plane applications. For each BTS, an IP address is configured in a /29 subnet for each of the VLANs. All BTSs are connected to both controller site/edge routers. At least 3 IP addresses are therefore, needed per subnet, one for the BTS and two for the physical interfaces of the routers. The smallest possible subnet size is /29 providing 6 hosts IP addresses. For the WCDMA BTS OAM subnet another /29 subnet is used, two IP addresses can be used for the BTS management applications another four are available for potential site support equipment.

2.9.2

Routing configuration in MBH Each of the BTSs has an L2 connection to both routers, see Figure 2: Common MBH topology. Two different approaches can be used to configure the next-hop router in the BTS. A static route to each of the two routers can be configured and one of them can be bound to a corresponding BFD session. Only the routes associated with an active BFD session or which are not bound to BFD session would be in use. Alternatively, the two routers could use HSRP/VRRP to provide a single IP address as next hop gateway to the BTS. In this case, a single static route towards this IP address needs to be configured in the BTS. The WCDMA and LTE BTS support the binding of BFD sessions to static routes; therefore both approaches can be used. For GSM, HSRP/VRRP is the only option. Within each of the configurations, a particular approach is used for all RATs to reduce configuration complexity. In the GSM+WCDMA and GSM+LTE, configuration HSRP/VRRP is used. In the WCDMA+LTE configuration BFD-triggered static routes are used.

2.9.2.1

Routing configuration with BFD-triggered static routes For WCDMA and LTE BTS, a static route is configured in the BTS for each of the used VLANs. One of the routers is considered the primary. As long as the route between the primary router and a BTS is available, the traffic will be exchanged via this router. Only if this route is not available due to link failure or router failure, the traffic will be exchanged via the second router.

The route between the primary router and the BTS is bound to a BFD session. In case the BFD session is down, the traffic is redirected via the other router. On the WCDMA and LTE BTS, the features RAN2440 and LTE866 Fast IP Rerouting are used, respectively. The management planes are separated from the other traffic. Therefore, on each site, 2 VLANs are used for the WCDMA traffic. BTS site1

LTE BTS

AP 20.3.1.6/29

10.3.1.6/29 10.3.2.6/29

WCDMA BTS

AP BFD

L2 network

10.3.1.1/29 10.3.2.1/29

Router1 10.0.1.1/30

10.3.1.2/29 10.3.2.2/29

10.0.1.2/30

Router2

Figure 4: Routing configuration for BFD-triggered static routes The site routers are connected to an additional VLAN. This connection is used to reroute traffic via the other site router in case the direct connection between router and BTS is broken. One of the routers is considered as primary router for this BTS site. In this example, this is Router1. The primary router might be different for different sites to distribute the load in normal operation. As indicated in Figure 4: Routing configuration for BFD-triggered static routes, a BFD session is configured between the primary router and the BTS site. More specifically, the BFD session is configured to the VLAN for WCDMA user, control, and synchronization planes. High-priority traffic is carried here and correspondingly, good performance objectives are required from the underlying Ethernet service. Hence there should be no congestion impacting the BFD session. A corresponding configuration is done for the LTE BTS, with the BFD session configured on the VLAN for LTE user and control plane. The following explanations for WCDMA apply for the routing configuration of the LTE BTSs as well. In Router1, the static routes towards the WCDMA BTS are bound to a BFD group. The BFD session on the VLAN for WCDMA user, control plane and synchronization plane is an active session. The other BFD sessions are passive ones. Both routers exchange the status of their routes towards the BTS via OSPF, thereby avoiding an additional BFD session between the BTS and Router2 as well as potential routing loops. The interfaces on the two routers used for the interconnection are configured to the same OSPF area. The static routes towards the BTS are redistributed to the OSPF area on both routers. OSPF convergence times do not impact the switchover times, as OSPF is used only to reinstall routes after recovery from a failure. No other routers are connected to this OSPF area in the configurations in this document. On Router1, the static routes need to have preference over the routes learned via OSPF, whereas on Router2 the routes learned via OSPF have preference. Therefore, the administrative distance of the static routes in Router1 is set to 1 and Router2 is set to 120. The administrative distance of OSPF is globally set in both routers to 110. The administrative distances for static routes in Router1 and for OSPF are the default

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settings; hence, no explicit configuration is needed. On Router2, the administrative distance has to be set explicitly for each of the routes; the static routes become floating static routes. An overview of the downlink routes is provided in Table 20: Static route configuration for downlink traffic. Traffic for WCDMA BTS OAM subnet – 20.3.1.0/29 – is routed via the corresponding transport management plane address – 10.3.1.6. Router

Destination address

Next-hop address

Administrative distance

BFD group

Status in BFD group

Router1

20.3.1.0/29

10.3.1.6

1

“Site1”

Passive

Router2

10.3.2.6/32 20.3.1.0/29

10.3.2.6 10.3.1.6

1 120

“Site1” -

Active -

10.3.2.6/32 10.3.2.6 120 Table 20: Static route configuration for downlink traffic

-

In the WCDMA BTS, a BFD session is configured for the VLAN for user, control, and synchronization plane. This session is used on all traffic planes to define a static route towards Router 1; static routes with lower preference are configured towards Router 2. A default route is configured on the management plane VL AN towards Router 2. This is used as a last resort. In case of misconfigurations, the BTS can still be managed via this route and the configuration can be corrected. Preference of this route does not matter as it is the least preferred route due to the prior longest prefix matching. The parameters in the WCDMA BTS are summarized in Table 21: WCDMA BTS uplink route configuration. Traffic plane

Destination address

BTS OAM

Next-hop gateway 10.3.1.1 10.3.1.2 10.3.2.1

Netact, OMS, OMU 0.0.0.0/0 WCDMA user, RNC user plane address, control, RNC control plane synchronization address, IEEE1588 plane master RNC user plane address, 10.3.2.2 RNC control plane address, IEEE1588 master Table 21: WCDMA BTS uplink route configuration

Preference 5 1 5

BFD session 1 1

10

-

The BFD session is configured with parameters as shown in Table 22: WCDMA BTS BFD session parameters. Corresponding parameters have to be configured in Router1, especially the intervals and the amount of packets lost before the sessions are considered down should match the values in the BTS. Parameter

Value 10.3.2.1 3 Empty 1 10.3.2.6

comment Router1 0.9 seconds to recognize route interruption Not needed -

Parameter

Value

comment

3784

Default Default -

300ms 300ms Table 22: WCDMA BTS BFD session parameters

2.9.2.2

Routing configuration with HSRP/VRRP When using HSRP/VRRP to provide a single virtual IP address as next-hop gateway to the GSM BTS, one of the site routers is considered the primary router (HSRP is configured such that this router is also the HSRP master in normal operation). The HSRP messages are exchanged via the MBH network. A router failure, a link break at the attachment point or a connectivity break inside the L2 network between these two controller site attachment points will trigger the HSRP slave to become HSRP master. In the case of a router failure or a link break, the corresponding router will not continue to send downlink traffic to the BTS. A connectivity failure inside the L2 backhaul network might not be recognized by the routing engine, even if the HSRP role has changed. In this case, the router will continue to send downlink traffic to the BTS, and traffic will be lost. The most common error cases are router or link breaks at the attachment points, which will be handled correctly. The risk of lost downlink traffic due to unrecognized connectivity breaks can be mitigated by different technical means such as tearing down interfaces in case of a connectivity break in an Ethernet service. Such means are vendor specific and are therefore not described in this document. BTS site1 20.3.1.6/29

10.3.1.6/29 10.3.2.6/29 10.3.3.6/29

WCDMA BTS GSM BTS

AP 10.3.1.1/29

AP L2 network

10.2.1.6/29 10.2.2.6/29

HSRP

10.3.2.1/29 10.3.3.1/29 10.2.1.1/29 10.2.2.1/29

10.3.1.2/29 10.3.2.2/29 10.3.3.2/29 10.2.1.2/29 10.2.2.2/29 10.3.1.3/29 10.3.2.3/29 10.3.3.3/29 10.2.1.3/29 10.2.2.3/29

Router1

Router2

Figure 5: Routing configuration for HSRP This setup is explained in more detail subsequently for co-located GSM and WCDMA BTS. Routing in an LTE BTS can be configured similarly to a WCDMA BTS, except that there is just one VLAN for user plane traffic. IP addresses examples for this configuration are summarized in Table 23: VLAN and IP address overview. Traffic plane

VLAN Id

GSM management plane

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BTS IP address 10.2.1.6/29


Router1 IP address 10.2.1.2/29

Router2 IP address 10.2.1.3/29

Virtual router IP address 10.2.1.1/29

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Traffic plane

VLAN Id

BTS IP address

Router1 IP address

Router2 IP address

Virtual router IP address

GSM user, control, synchronization plane

1001

10.2.2.6/29

10.2.2.2/29

10.2.2.3/29

10.2.2.1/29

WCDMA management plane (trsp)

1501

10.3.1.6/29

10.3.1.2/29

10.3.1.3/29

10.3.1.1/29

WCDMA OAM subnet

n/a

20.3.1.5/29 4 20.3.1.6/29

n/a

n/a

n/a

WCDMA high-priority user, control, synchronization plane WCDMA low-priority user plane

2001

10.3.2.6/29

10.3.2.2/29

10.3.2.3/29

10.3.2.1/29

2501

10.3.3.6/29

10.3.3.2/29

10.3.3.3/29

10.3.3.1/29

3

Table 23: VLAN and IP address overview 5

Two HSRP groups are configured per GSM BTS, one for each VLAN. Additional groups are configured for the WCDMA or LTE BTS. The primary router is the HSRP master under normal conditions. HSRP preempt is used to move the master role from the secondary to the primary router if this becomes available again after failure. Table 24: HSRP configuration summarizes the HSRP configuration of Router1 and Router2 regarding the GSM BTS on site1. A similar configuration has to be replicated for each GSM BTS. In case the traffic shall be shared among both routers in normal operation, the master role should be on Router1 for half of the BTS sites and on Router2 for the other half of the BTS sites. Router

Router1

Router2

3 4 5

VLAN ID

Traffic plane

IP address

HSRP Group

Priority

Virtual Router IP

501


10.2.1.2/29

1

110

10.2.1.1/29

1001


10.2.2.2/29

2

110

10.2.2.1/29

501

GSM management

10.2.1.3/29

1

90

10.2.1.1/29

mPlaneIpAddress ftmIpAddr

One of the two HSRP groups can be configured as master and the other HSRP group to follow the state of the master group. This optimization has not been explained in detail for the sake of readability.

Router

VLAN

Traffic plane

IP address

HSRP

plane 1001


10.2.2.3/29

2

90

10.2.2.1/29

Table 24: HSRP configuration

2.9.3

IP address for SSE As a typical example of site support equipment, NSN Green Energy Controller is installed on each BTS site. This device allows monitoring and controlling additional equipment to provide energy on a BTS site. This controller can be reached via a single IPv4 address from a management system such as Netact. In a WCDMA BTS, this address can be taken from the OAM subnet of the BTS. In this document, a /29 subnet has been used and six IP addresses are available in this subnet. In an LTE BTS, a dedicated OAM subnet has to be defined, which would then contain the IP addresses for the management plane application as well as for SSE. The corresponding traffic will be carried together with the management plane traffic of the BTS to which the Green Energy Controller is connected. The Green Energy Controller does not use VLAN tags, but as the traffic is routed through the BTS there is no problem to use a VLAN towards the backhaul without having to use VLANs for the directly connected SSE. The traffic volume is considered negligible. The Green Energy Controller is connected to the port labeled ‘BBU’ (battery backup unit) of the WCDMA or LTE system module. In the IP filtering rules, the restricted mode for LMP is switched off. This adds an exception rule to the firewall, allowing traffic from any address in the BTS OAM subnet to be received from any of the ports for local management and site support equipment. A route is configured for the management system of the Green Energy Controller using the same next hop address as other management plane traffic. In a GSM BTS, the Green Energy Controller would be connected to one of the transport ports; there is no BBU port as in the WCDMA and LTE BTS. The LTE BTS allows remarking the DSCP of traffic from the SSE. Although the Green Energy Controller marks its egress traffic with DSCP 0, the LTE BTS ensures this value by configuring the DSCP for the traffic type SSE to 0. In case the Green Energy Controller is connected to a WCDMA, such marking cannot be enforced. Remarking of downlink SSE traffic is done in the edge routers. In the WCDMA+LTE and GSM+LTE configuration, the SSE is connected to the hub BTS on a site. This has the slight benefit that connectivity of SSE depends on as few BTSs as possible. In the GSM+WCDMA configuration, the GSM BTS is used as hub BTS, but on BTS site 2, all Ethernet ports are used already for transport purposes. Therefore in this configuration, the WCDMA BTS, that is the leaf BTS on each site are used to connect SSE.

2.9.4

Controller site Cisco76xx based controller site solutions are used. For radio technology specific IP configurations refer to:

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

GSM: BSC TRANSPORT SITE SOLUTION, RG20 Mother Document, Scenarios and Requirements and BSC TRANSPORT SITE SOLUTION RG20 Daughter Document External L2/L3 Equipment



WCDMA: Configuring WCDMA and Flexi Direct Transport and RAN1884: Cisco 76xx as RNC Site Router, in Nokia Siemens Networks WCDMA RAN



LTE: Configuring LTE Transport

2.10 Traffic Aggregation on BTS site The traffic at the BTS site is aggregated by one of the BTSs by the BTS integrated Ethernet switch. This hub BTS aggregates the traffic from both a co-located BTS as well as from a chained BTS site (optional). Therefore, this hub BTS requires 3 Ethernet interfaces. The details of the connectivity and aggregation are shown in the following chapters. The BTS integrated Ethernet switch of the GSM and LTE BTSs is able to switch Ethernet frames of up to 1632 bytes. This allows configuring of an MTU of 1560 bytes for LTE and thereby to avoid IP fragmentation. In the WCDMA BTS, Ethernet switch 6 frames of up to 1522 bytes can be handled. The MTU in co-located BTS must be set to 1500 bytes. The egress traffic of the hub BTS itself should be shaped. This traffic together with other BTSs traffic, which is shaped individually at origin, is aggregated in the hub BTS's Ethernet switch. At least two Ethernet services are used per BTS chain in the configurations in this document. Therefore the BTS integrated switch cannot be used to shape the uplink traffic, as it can shape the traffic per interface only. Traffic bursts, even when short, cause delay to high-priority packets. To avoid delay, the BTS integrated switches are configured to schedule the traffic at each of its interfaces in a QoS aware manner, the corresponding shaping rate is line rate (1 Gbps). The prioritization of traffic is achieved by classifying the traffic to queues based on PCPs and by using the default mapping of PCPs to queues. Note that the BTS integrated switch functionality is not used in the leaf BTS on a site. VLAN tags are preserved by the BTS integrated Ethernet switches. Filtering Ethernet frames at external ports based on VLAN IDs is switched on for the WCDMA and LTE BTSs acting as hub BTS. This limits broadcast storms. The integrated Ethernet switch in the GSM BTS does not support such filtering. The exemplary VLAN IDs used in this document are shown in Table 25: VLAN IDs. Site


GSM user, control, synchronizatio n plane

WCDMA management plane

WCDMA (highpriority) user, control, synchroniza tion plane

WCDMA low-priority user plane

LTE management plane

LTE user, control, synchronizatio n plane

1

501

1001

1501

2001

2501

3001

3501

2

502

1002

1502

2002

2502

3002

3502

6

Switching of Ethernet frames of up to 1632 bytes will be supported in future releases of WCDMA RAN.

Site

3


503

GSM user, control, synchronizatio n plane


WCDMA (highpriority) user, control, synchroniza tion plane

WCDMA low-priority user plane

1003

1503

2003

2503


LTE user, control, synchronizatio n plane

Table 25: VLAN IDs Note that VLAN filtering is applied in the GSM+LTE and in the WCDMA+LTE configuration. WCDMA (in WCDMA+LTE configuration) and LTE BTSs in the BTS chain with sites 2 and 3 are connected to the same VLANs. GSM BTSs always use a dedicated VLAN.

2.11 Security IPsec is not considered in this release of the document. In case IPsec is used, a larger overhead due to IPsec encapsulation has to be considered. Especially, shaping towards bandwidth profiles at attachment points should be done after IPsec encapsulation such that the larger overhead is handled correctly and packet discard at the attachment point is avoided. If IPSec would be used, it must be terminated in each BTS individually. Hub BTSs cannot act as IPSec GW for a whole site. For WCDMA and LTE BTS, the automatic firewall features are used. No specific configuration is needed.

2.12 Auto-configuration Auto-connection and auto-configuration can be used to deploy additional W CDMA and LTE BTS in the field. As the hub BTSs are configured as Ethernet switches, colocated or chained BTSs are connected via Ethernet with the edge routers. The edge routers have to be configured as DHCP relay, relaying the DHCP requests to a suitable OMS.

2.12.1 Measurements The BTSs are configured to monitor delay and delay variation of the transport network. For GSM, the packet Abis delay measurements are used (BSS30395: Packet Abis Delay Measurement), for WCDMA and LTE, TWAMP-light is in use (RAN1900/LTE574 IP Transport Network Measurement). TWAMP-light refers to RFC5357, appendix I. The Cisco routers on the controller site do not provide sufficient support to act as reflectors for the measurements, see IP Transport Monitoring with Standalone Devices. Therefore for WCDMA, the measurements are done between the BTS and RNC and for LTE a dedicated device is used at the edge router site. The measurements are performed separately for the BTS of each technology, thereby allowing independent monitoring.

2.12.1.1 GSM measurements When the measurements are activated in the BSC, the BTS sends a UDP packet to the BSC every 5 seconds. These packets are reflected at the BSC and the BTS measures the round trip time. The BTS reports each measurement to the BSC, which can then derive minimum, average, and maximum round trip time and minimum and maximum round trip time variations.

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Except for starting the measurements on the BSC, there are no parameters to be configured. The BTS will send the UDP packets to the user plane IP address of the BSC and will use the corresponding DSCP marking.

2.12.1.2 WCDMA measurements The BTS is configured to send TWAMP messages (on top of UDP) to the RNC, which are reflected there and the BTS can take the measurements. The BTS is configured to take the measurements separately for the high and low-priority user plane. Typical message sizes for the different traffic planes are used; the destination port (dstPort) is the one for UDP echo at the RNC. On the high-priority user plane, there are actually two different DSCPs for voice and for DCH NRT traffic. Just one measurement is used with the DSCP corresponding to voice, allowing monitoring whether the required performance objectives for voice are met. For both user planes, two lost measurement packets will trigger an alarm. In 15minute measurement interval, 450 measurements are done per measurement. Two lost packets correspond to a packet loss of 0.44%. If the round trip time for the high priority user plane exceeds 20 ms (twice the delay as indicated in Table 7: Attributes of performance classes), the RTT alarm is raised. This alarm indicates that the performance objective for packet delay of the Ethernet service has been violated. For the low-priority user plane, the threshold is set to a value slightly smaller than the threshold for HSDPA CC. Round trip time has to be larger than the threshold for one minute to raise the alarm. Therefore sporadically exceeding the bandwidth with a corresponding increase in the delay does not trigger the alarm. The threshold for HSDPA CC is 50 ms, for the round trip time alarm, a value of 45 ms is used assuming that mostly one of the two directions experiences a delay. This alarm indicates that the backhaul link has been congested over an extended period of time, indicating that the backhaul connection does not provide sufficient capacity. In totality, 1 message per second is sent, meaning that there will be one message per 2 seconds for each of the two measurements. The settings are summarized in Table 26: WCDMA IP measurements. Traffic plane

messa geSize

dest Port

DSC P

plrAlarm Thresho ld

rttAlarm Thresho ld

twampS ourcePo rt

twampM essageR ate

49151

RATE_1 (1msg per second)

high-priority user plane

100 bytes

7

46

0.44%

20 ms

low-priority user plane

1000 bytes

7

18

0.44%

45 ms

Table 26: WCDMA IP measurements The IP addresses used are the corresponding user plane addresses on both BTS and RNC.

2.12.1.3 LTE measurements The LTE BTS is configured to send TWAMP messages (on top of UDP) to a dedicated device at the site of the edge routers. This device reflects the UDP messages and the BTS can take the measurements. The edge routers might have limitations in replying to UDP echo; therefore, a dedicated device is used. Here, an Accedian Metronode device is used; see IP Transport Monitoring with Standalone Devices. It is connected

to both edge routers in a redundant way. It is acting as UDP echo server only; it does not perform measurement itself. The setup is shown in Figure 6: Accedian Metronode as measurement device for LTE . BTS site1

LTE BTS

Router1

AP

TWAMP/UDP

UDP echo

L2 network

AP

Accedian Metronode

Router2

Figure 6: Accedian Metronode as measurement device for LTE The configuration is similar to the one for WCDMA, see Chapter 2.12.1.2: WCDMA measurements. For the low-priority user plane, the threshold is based on the end to end delay budget for NRT traffic, which is 300 ms. Leaving some delay budget for air interface scheduling, the alarm will be raised when the RTT exceeds 200 ms. It is assumed that only one of the two directions experiences a delay at a given time, see Table 27: LTE IP measurements. Traffic plane

Message size

destPort

high-priority user plane

100 bytes

7

low-priority user plane

1000 bytes

7

plrAlarmT hreshold

rttAlarmThr eshold

twampSour cePort

twampMessa geRate

46

0.44%

20 ms

49151

0

0.44%

200 ms

RATE_1 (1msg per second)

DSCP

Table 27: LTE IP measurements As the LTE BTS transmits all user plane traffic on a single V LAN, the measurements for both high-priority (QCI1) and low-priority (QCI6-9) traffic are performed on the same VLAN and using the same IP addresses at each of the peers.

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3 3.1

GSM and WCDMA Recommended network configuration description This reference configuration describes a configuration for a GSM and a WCDMA RAN over a shared mobile backhaul network. Both RATs use IP/Ethernet for backhaul The main characteristics of the network considered in this case are as follows: 















3.1.1

Backhaul network overview: The backhaul network provides L2 connectivity between controller site routers and BTS sites. Three Ethernet services are used per BTS site, one for high and one for low-priority WCDMA traffic and one for GSM traffic. The backhaul network is agnostic concerning the underlying technology used to provide the L2 services. A typical implementation of such a transport service is VPLS using an MPLS based network. Backhaul network sharing: The network is shared by both GSM and WCDMA RAN. There might be additional services using the network, but there is guaranteed capacity allocated to the mobile network. The dimensioning of the guaranteed capacity should follow the mobile network dimensioning. Synchronization: An IEEE1588 master is located on the controller site. The GSM BTS on each site is synchronized via IEEE1588 and synchronizes the co-located WCDMA BTS with SyncE. Network redundancy: It is assumed that the transport network features inherent redundancy, transparently protecting the mobile traffic against failures inside the network. Controller site redundancy: Controller site routers are doubled for redundancy. The radio controller connections to the network are redundant, whereas for each BTS the traffic is carried over a single link in the last mile. The redundancy solution for the radio controllers is the usual, HSRP/VRRP based one. Backhaul network bandwidth: The backhaul network supports bandwidth provisioning for the BTSs. The provisioned bandwidth is assumed to be always sufficient for the WCDMA traffic subject to CAC and for the controlled amount of GSM traffic. The provisioning of bandwidth is transparent to the mobile network; it is considered part of the network operation. Backhaul network QoS: The backhaul network is able to prioritize traffic based on VLAN p-bits. VLAN usage: VLANs are deployed in the backhaul network to separate the BTS broadcast domains and to facilitate mapping of traffic to Ethernet services. At BTS, management plane is separated to its own VLAN. In this configuration, VLANs are configured to RNC, BSC, and controller site routers.

General configuration In this recommended configuration, three Ethernet services per BTS site are used; each Ethernet service providing a single performance class. For the BTS chain, two sets of Ethernet services terminate at the attachment point, thereby hiding the access network topology at the controller site. This is shown in Figure 7: Several Ethernet services with single performance class .

BTS site 2

BTS site 3

WCDMA BTS

WCDMA BTS

AP

ToP master

AP GSM BTS

GSM BTS

L2 network

RNC BSC

BTS site 1

WCDMA BTS

A/Iu

GSM BTS

Figure 7: Several Ethernet services with single performance class GSM is considered the fallback network for voice services and uses a separate Ethernet service. The GSM BTS is used as hub BTS on each of the sites, thus the availability of the GSM BTS on a site does not depend on the availability of any other (aggregating) BTS. Two of the Ethernet services per BTS site provide performance class High and the remaining one performance class Low. The Ethernet service with performance class Low is used for HSPA NRT traffic and for WCDMA management plane traffic. All the other traffic of a site is carried within the Ethernet services with performance class High. That is all GSM traffic including management plane in one Ethernet service with performance class High and all WCDMA RT, DCH NRT, and control plane traffic in the other Ethernet service with performance class High. The Ethernet services with performance class Low are dimensioned such that the average bit rate is provided as guaranteed bandwidth and the peak bit rate is provided as peak bandwidth. Some additional bit rate is provided for the management plane. For Ethernet services with performance class High the bandwidth is provided as guaranteed bandwidth equal to peak bandwidth, separately for WCDMA and GSM traffic. For the traffic amount for downlink, see Chapters 1.5.1 and 1.5.2. Traffic type

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Average [kbps]

Peak [kbps]

GSM CS user plane

n/a

1500

GSM PS user plane

n/a

2100

GSM control plane

n/a

400


n/a

64

IEEE1588

16

16

WCDMA control plane

507

507

WCDMA user plane RT + DCH NRT

3701

3701

WCDMA CCH

66

66


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Traffic type

Average [kbps]

Peak [kbps]

WCDMA user plane HSPA NRT

4418

41200


64

n/a

Table 28: GSM and WCDMA traffic amount For GSM traffic, 1500 kbps + 2100 kbps + 400 kbps + 64 kbps + 16 kbps = 4080 kbps are needed as guaranteed bandwidth on the Ethernet service with performance class High. For WCDMA, 507 kbps + 3701 kbps + 66 kbps = 4274 kbps are needed. For the WCDMA, Ethernet service with performance class High, using the 1 Mbps granularity for bandwidth profiles, 5 Mbps of guaranteed bandwidth are used for these Ethernet services. For the Ethernet service with performance class Low, there is 4418 kbps + 64 kbps = 4482 kbps average throughput, therefore 5 Mbps of guaranteed bandwidth is required. The peak throughput of the user plane is 41.2 Mbps; an overall capacity of 45 Mbps leaves sufficient room for the peak user plane throughput and more than average throughput for the management plane. The peak bandwidth is set to 45 Mbps. The guaranteed bandwidth and peak bandwidth values are summarized in Table 29: GSM/WCDMA information rates. Ethernet service

Performance class

Guaranteed bandwidth [Mbps]

Peak bandwidth [Mbps]

ES 1

High

5

5

ES 2

High

5

5

ES 3

Low

5

45

Table 29: GSM / WCDMA information rates These specific rates are used to determine shaping rates and parameters for CAC.

3.1.2

Feature usage The most relevant features for deploying GSM and WCDMA over a shared backhaul network in this recommended network configuration are listed below:

3.1.2.1

3.1.2.2

GSM 

BSS101417 QoS aware Ethernet Switching



BSS21439 Packet Abis Sync. ToP IEEE1588v2















BSS30450 Packet Abis Synchronous Ethernet

WCDMA 





3.2 3.2.1












RAN1886 Efficient Transport for small IP packets




RAN parameters for the configuration General The available bandwidth is statically divided between GSM and WCDMA per site. The traffic of each of the radio technologies is shaped independently so as not to exceed Ethernet service capacity. Only WCDMA traffic is carried on the Ethernet services with performance class Low and is shaped separately. As a consequence, no shaping to Ethernet service bandwidths is applied by the BTS internal Ethernet switch in the uplink direction. Within this configuration, there are no bottlenecks in downlink direction as seen from the hub BTS, therefore, there is also no shaping of the BTS in downlink direction to a rate smaller than line rate. The burst size of the Ethernet services with performance class High is 500 kbit, of the Ethernet services with performance class Low is 4.5 Mbit. As each Ethernet service is used by a BTS of one RAT only, the bursts can be controlled separately per RAT. On BTS site 2, all three Ethernet interfaces of the GSM BTS acting as hub are used, leaving no possibility to connect SSE. Therefore, SSE is connected to the WCDMA BTS and this is done consistently on all BTS sites.

3.2.2

Shaping The capacity of the Ethernet services with performance class High is 5 Mbps and provisioned as guaranteed bandwidth. The downlink GSM and WCDMA traffic is controlled by BSC and RNC resp. 





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The GSM traffic of both VLANs in total is monitored in the BTS and once the threshold or packet loss thresholds are exceeded for a predefined time, the traffic volume is reduced, see Chapter 2.5.1: Packet Abis Congestion Control. No shaping of GSM traffic in the edge router is needed. The WCDMA high-priority user plane traffic including common channels does not exceed 3770 kbps on Ethernet level, corresponding to 3370 kbps on IP level. At least 435 kpbs are needed for signaling traffic, no reservation is needed for management traffic for this BTS as the management plane traffic is carried together with the low-priority user plane. In total, at least 3805 kbps of committed bandwidth is needed. The RNC shapes the traffic accordingly, as committed bandwidth of this IP based route is configured to 3900 kbps and by internal flow control (IFC) is activated. NPGE load sharing cannot be used, otherwise shaping via IFC would not be available. The WCDMA low-priority traffic is shaped in the RNC by using IFC to 40000 kbps on IP layer, corresponding to about 41000 kbps on Ethernet layer. This leaves 4 Mbps for management plane traffic. Note that the aggregate of management plane traffic and low-priority user-plane traffic is not shaped. HSPA congestion control is used to react in case the peak bandwidth of the Ethernet service capacity is not available.


DN09123915 Issue 03


Two IP based routes for each WCDMA BTS are configured in the RNC as shown in Table 30: IP based route configuration. These values are configured on IP layer, see Table 3: Traffic demand on Iub per single BTS. Parameter name

IPBR for high priority traffic

IPBR for low priority traffic

Comment

3900

40000

Used for call admission control

0

1000

Maximum value possible, but no impact on shaping

435

0

ON

ON

4500

41000

Table 30: IP based route configuration In uplink direction, the traffic is shaped to avoid packet drop by the policers at the attachment point. The parameters below are measured on Ethernet level. Each BTS shapes its own uplink traffic. The available line speed of the last mile (1Gbps) is larger than the sum of peak bandwidth values of the Ethernet services. The BTS integrated switch is used for traffic prioritization only see Chapter 2.10: Traffic Aggregation on BTS site. The traffic is aggregated in the GSM BTS, which has limited buffer space for Ethernet frames in its integrated switch. To avoid packet drops, the BTS should not generate bursts in uplink direction. The GSM BTS shapes all its uplink traffic on interface level. Uplink traffic shaping is switched on by setting the parameter ULTS to shaping-committed (1). The parameter ULCIR is set to 5000 kbps. Parameter name

Value

Comment

1522

maximum size of a single Ethernet frame

5000

All traffic planes together

shapingcommitted (1) Table 31: GSM BTS uplink shaping parameters The WCDMA BTS shapes its traffic per VLAN; there is no similar mechanism as the internal flow control in the RNC to limit the amount of high-priority user plane traffic in the uplink direction. The uplink management plane and low-priority user plane traffic are shaped separately. The shaping rate is set to the remaining capacity of the Ethernet service after provisioning capacity for the user plane.

Parameter name

high-priority user, control, synchronizati on plane

lowpriority user plane

manage ment plane

True (1)

True (1)

False (0)

1522

1522

1522

5000

41000

4000

4000

41000

n/a

Comment

6-queue schedulers for VLANs with user plane traffic, single queue for management plane

Used for CAC: note that a small reservation is needed for frame protocol control PDUs

Path

Configured per BTS, shaping per VLAN

false(0)

Ethernet overhead is considered

Table 32: WCDMA BTS uplink shaping parameters The configured bandwidth and the location of the shapers are summarized in Figure 8: Shaping for GSM and WCDMA. The lower part of the diagram shows whether shaping is done per interface or VLAN in the BTS, the corresponding shaping rate, which VLANs are mapped to which Ethernet service, the performance class, guaranteed and peak bandwidth of the Ethernet services, and the shaping rates in the RNC. This configuration is used on each BTS site. BTS site1

WCDMA BTS GSM BTS

AP

w h L o i g h i g P C C H H 3 P E S S 2 P C E S 1 E

AP

Router1 ToP master

L2 network

RNC Router2

5Mbps both VLANs VLAN 5Mbps

Phys IF

VLAN

4Mbps

VLAN

41Mbps

GSM M GSM U/C/S WCDMA Uh/C/S WCDMA M WCDMA Ul

BSC

ES1 PC High 5/5Mbps ES2 PC High 5/5Mbps

5Mbps both VLANs (PAbis CC) 4.5Mbps IFC at RNC

ES3 PC Low 5/45Mbps

no shaping 41Mbps IFC at RNC

Figure 8: Shaping for GSM and WCDMA

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3.2.3

Synchronization On each BTS site, the GSM BTS connected to the backhaul network also acts as a synchronization hub. It is itself synchronized via IEEE1588, assuming that Synchronous Ethernet is not provided by the MBH network. The co-located WCDMA BTS is then synchronized via Synchronous Ethernet by the GSM BTS. An overview is provided in Figure 9: Synchronization overview for GSM and WCDMA co-location . BTS site 2

BTS site 3

WCDMA BTS

WCDMA BTS

SyncE

SyncE

IEEE1588 ToP master

GSM BTS

GSM BTS

L2 network

RNC BSC

BTS site 1

WCDMA BTS

SyncE GSM BTS

Figure 9: Synchronization overview for GSM and WCDMA co-location The GSM BTS is configured as described in Table 33: GSM BTS as IEE1588 slave. Parameter

Value 16 msg/sec 2 min 2 sec 300 sec

Table 33: GSM BTS as IEEE1588 slave The GSM BTS regenerates Synchronous Ethernet on its interfaces without explicitly configuring this. The use of SSM messages has to be enabled on the GSM BTS. The WCDMA BTS receives its synchronization via Synchronous Ethernet, see Table 34: WCDMA BTS as SyncE slave. A single clock source is configured: Synchronous Ethernet. SSM messages from the GSM BTS are recognized. That is when the GSM BTS is indicating holdover mode via SSM messages, the WCDMA BTS will switch to holdover, too. Synchronization alarms will be raised for the BTS in each RAT, indicating the problem even if the BTSs are managed separately. Parameter

Value

Comment

EEC1 (3) false(0)

This BTS is a slave only

clkSyncE (3) The interface where the GSM BTS is connected

Parameter

Value

Comment

1 ssmPRCorPRS (1) true (1) 5 sec

(default)

1 Table 34: WCDMA BTS as SyncE slave

3.2.4

BTS site 1 (standalone site) BTS site 1 is not part of a BTS chain.

BTS site 1

FTIB

WCDMA BTS GSM BTS

UNI FIQB

Figure 10: GSM + WCDMA BTS site 1 (standalone site) It is assumed that the GSM BTS is connected via optical 1000Base-X to the attachment point; a 1000Base-T connection is used to connect to the WCDMA BTS. Bursts of downlink WCDMA traffic can be forwarded to the WCDMA BTS without having to buffer them in the GSM BTS due to different link speeds. The burst size of the ingress rate limiter in the GSM BTS integrated switch is much smaller than the burst sizes of the Ethernet service. Using the ingress rate limiter might cause arbitrary packets to be dropped. Therefore, ingress rate limiting is not used in this BTS. The QoS aware BTS integrated switch is not used in the WCDMA BTS, therefore ingress rate limiting by the BTS integrated switch is not applicable. The ingress rate limiting by RAN1749 BTS Firewall still applies.

3.2.5

BTS site 2 (hub site) BTS site 2 is a hub site that relays traffic between the network and another BTS site. One of the BTSs at this site aggregates the traffic both from the leaf BTS site as well as from a co-located BTS; therefore, an additional hop for the traffic of the leaf BTS site is avoided. The GSM BTS provides the hub functionality; all three Ethernet interfaces of FIQB unit are used.

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DN09123915 Issue 03


BTS site 2

BTS site 3

WCDMA BTS

GSM BTS

FTIB

AP FIQB

Figure 11: GSM + WCDMA BTS site 2 (hub site) It is assumed that the GSM BTS is connected via optical 1000Base-X to the attachment point. A 1000Base-T connection is assumed to connect to the leaf BTS nd site. The 2 electrical interface is also configured to 1000Base-T to connect the local WCDMA BTS. As the BTS on the leaf site shape its traffic separately per VLAN, there could be small traffic bursts. These are in the order of the accepted burst size of the ingress rate limiter of the FIQB transport module. To avoid any packet drop, the ingress rate limiter of the GSM BTS on site 2 is switched off at the interface from BTS site 3.

3.2.6

BTS site 3 (leaf site) The configuration on this site is identical to the standalone site, see Chapter 3.2.4: BTS site 1 (standalone site).

3.2.7

BTS IP configuration The BTSs are configured as described in Chapter 2.9.1: VLAN usage at BTS site. The Green Energy Controller is connected to the WCDMA BTS on each site as described in Chapter 2.9.3: IP address for SSE.

3.2.8

Controller site The edge routers separate the BSC and RNC site solutions from the needs of the shared mobile backhaul network. There are no specific requirements for the BSC site solution. Recommended BSC site solutions are described in the following documents: BSC TRANSPORT SITE SOLUTION, RG20 Mother Document, Scenarios and Requirements and BSC TRANSPORT SITE SOLUTION RG20 Daughter Document External L2/L3 Equipment . There are no specific requirements for the RNC site solution. Recommended RNC site solutions are described in the following documents: Configuring WCDMA and Flexi Direct Transport and RAN1884: Cisco 76xx as RNC Site Router, in Nokia Siemens Networks WCDMA RAN No shaping of downlink traffic is required in the site routers, the routing and HSRP configuration on the MBH network is explained in Chapter 2.9.2.2: Routing configuration with HSRP/VRRP.

4

GSM and LTE This reference configuration describes a configuration for a GSM and an LTE RAN over a shared mobile backhaul network. Both RATs use IP/Ethernet for backhaul. The main characteristics of the network considered in this case are: 















4.1 4.1.1

Backhaul network overview: The backhaul network provides L2 connectivity between controller site routers and BTS sites. Dedicated Ethernet services are used per RAT, and the same performance class is used for all traffic. The backhaul network is agnostic to the underlying technology used to provide the L2 services. A typical implementation of such transport service is VPLS using an MPLS based network. Backhaul network sharing: the network is shared by both GSM and LTE RAN. There might be additional services using the network, but there is guaranteed capacity allocated to the mobile network. The dimensioning of the guaranteed capacity should follow the mobile network dimensioning. Synchronization: An IEEE1588 master is located on the controller site. The LTE BTS on each site is synchronized via IEEE1588. The LTE BTS synchronizes the co-located GSM BTS via RP3-01. Network redundancy: It is assumed that the transport network features inherent redundancy, transparently protecting the mobile traffic against failures inside the network. Controller site redundancy: Controller site routers are doubled for redundancy. The BSC connections to the network are redundant, whereas for each BTS the traffic is carried over a single link in the last mile. The redundancy solution for the BSC is the usual, HSRP/VRRP based one. Backhaul network bandwidth: The backhaul network supports bandwidth provisioning for the BTSs. The provisioned bandwidth is assumed to be always sufficient for the LTE traffic subject to TAC and for the controlled amount of GSM. The provisioning of bandwidth is transparent to the mobile network and it is considered part of the network operation. Backhaul network QoS: Within the backhaul network, all traffic is carried as one performance class. Edge Routers and BTSs are configured to prioritize traffic based on the DSCP. VLAN usage: VLANs are deployed in the backhaul network to separate the BTS broadcast domains and to facilitate mapping of traffic to Ethernet services. At BTS, management plane is separated to its own VLAN. In this configuration, VLANs are configured to the BSC and the site routers as well.

Recommended Network Configuration Description General configuration In this recommended configuration, two or three Ethernet services per group of BTS sites are used, each Ethernet service providing the same performance class. One Ethernet service is used per GSM BTSs and the other is used for LTE. The traffic of the RATs is carried on separate Ethernet services to separate the GSM backhaul from other traffic. The LTE BTS of BTS site 2 as well as of BTS site 3 uses the same Ethernet service to increase the possibilities for statistical multiplexing among the traffic of these BTSs. GSM BTS use a dedicated Ethernet service each allowing to configure the Ethernet services for all GSM BTSs in the same way. For GSM BTS,

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DN09123915 Issue 03


there would be no multiplexing gain by carrying the traffic of several BTSs on one Ethernet service. This configuration is shown in Figure 12: Two Ethernet services with single performance class. BTS site 2

BTS site 3

GSM BTS

GSM BTS

AP

AP LTE BTS

LTE BTS

L2 network

BTS site 1

GSM BTS

ToP master

BSC

A/S1

LTE BTS

Figure 12: Two Ethernet services with single performance class Each Ethernet service provides a single performance class. This performance class must be suited for the most stringent requirements from the different traffic types that are the Ethernet services provide performance class High. As QoS unaware policers are used at the attachment points, no difference can be made between high- and lowpriority traffic. Therefore all the capacity of the Ethernet service is provided as guaranteed bandwidth, the peak bandwidth is equal to guaranteed bandwidth. According to Table 1: Average traffic per GSM BTS and Table 4: LTE traffic model, the traffic volumes for GSM and LTE are 4 Mbps and 72 Mbps respectively. As in Chapter 3, the Ethernet service for GSM is configured with more bandwidth that is a guaranteed bandwidth of 5 Mbps. 4 Mbps of the LTE traffic has to be considered as high-priority. For the Ethernet service of BTS site 1 a guaranteed bandwidth of 80 Mbps is used, for the Ethernet service of BTS sites 2 and 3 a capacity of 100 Mbps is used, increasing the potential gain by statistical multiplexing. 100Mbps is based on the maximum of peak bandwidth of one BTS (72000 kbps) and the sum of average bandwidth of both BTSs (2x41500 kbps) and rounded up to 100 Mbps. For LTE, the amount of high-priority traffic is far below the available capacity of the Ethernet services. LTE TAC is not needed and will not be used in this configuration. GSM Packet Abis congestion control will be used in the same way as in Chapter 3: GSM and WCDMA. The MTU of the LTE BTS is configured to 1560 bytes. Note that Ethernet frames of up to 2000 bytes can be carried across the Ethernet service. This allows sending 1500 byte end user packets across the LTE S1/X2 interfaces without causing IP fragmentation. The additional 60 bytes are needed for the GTP/UDP/IP overhead on the S1 and X2 interface.

4.1.2

Feature usage The most relevant features for deploying GSM and LTE over a shared backhaul network in this recommended network configuration are listed below.

4.1.2.1

GSM The GSM transport related features are listed as follows:













Other features used in the reference configurations are listed below 

4.1.2.2

BSS21520 RF Sharing GSM-LTE

LTE The LTE transport related features are listed as follows: 




LTE119 Gigabit Ethernet (GE) optical interface












LTE134 Timing over Packet









LTE649 QoS aware Ethernet switching



LTE931 Ethernet Jumbo Frames

Other features used in the reference configurations are listed as follows:

4.2 4.2.1



LTE447 SW support for RF sharing GSM-LTE



LTE746 IP based Filtering for BTS Site Support Equipment

RAN parameters for the configuration General The bandwidth on the Ethernet services for GSM is not shared with other traffic. The amount of GSM traffic on each Ethernet service is controlled with Packet Abis Congestion Control. The uplink LTE traffic is shaped in each BTS to avoid buffer overflows in the BTS integrated switch as well as to keep the traffic amount within the Ethernet service bandwidths. This implies that the capacity of the LTE Ethernet service for BTS sites 2 and 3 is shared statically in the uplink among the BTSs. In downlink direction the bandwidth is shared dynamically by shaping the traffic of both BTSs together in the edge routers. The burst sizes of the Ethernet services are 0.5 Mbit for the GSM Ethernet services, 8 Mbit for the LTE Ethernet service of the standalone site, and 11 Mbit for the LTE Ethernet service of the BTS chain.

4.2.2

Shaping In downlink direction, the traffic for each of the LTE Ethernet services is shaped in the edge routers to the Ethernet service bandwidth and burst size. The mapping of DSCPs to queues is defined in Table 14: 1SP+5WFQ scheduler. The downlink GSM

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traffic is controlled by Packet Abis congestion control, no shaping is needed in the edge routers. In uplink direction, each GSM BTS shapes its own traffic in the same way as in the GSM+WCDMA configuration, see Chapter 3.2.2: Shaping. The amount of LTE traffic with guaranteed bit rate is far less than the available bandwidth. According to dimensioning 2 Mbps of traffic with QCI1 are expected, whereas at least 80Mbps are available for LTE traffic per BTS chain. Therefore traffic admission control is not needed; the default values – 1000 Mbps – of the parameters tacLimitGbrNormal, tacLimitGbrHandover and tacLimitGbrEmergency are applied. For the LTE BTSs, the traffic on the two VLANs is shaped to avoid packet drop at the attachment point. For the LTE BTSs on site 2 and 3, the bandwidth is split statically in the uplink. The BTSs shape the traffic to a small burst size such that no large bursts can build up in uplink. Shaping takes layer 2 overheads into account. Parameter name

user, control, synchronizati on plane site 1

user, control, synchronizat ion plane site 2, 3

managem ent plane

Yes

Yes

No

1560

1560

1522

78000

49000

1000

Comment

prevent bursts

Configured per BTS, shaping per VLAN false(0)

Ethernet overhead is considered.

Table 35: LTE BTS uplink shaping parameters For BTS sites 2 and 3, three Ethernet services are defined. 2 VLANs are mapped to each Ethernet service. Note that both LTE BTSs are connected to the same VLANs. Therefore, X2 traffic among the two LTE BTSs does not traverse the MBH network. The guaranteed bandwidth at each attachment point for the LTE Ethernet service is 100 Mbps. In downlink direction, the site routers have to shape the traffic of both VLANs together to 100 Mbps. Downlink GSM traffic is controlled using Packet Abis congestion control. In uplink direction, the GSM BTS shape their egress traffic per interface, whereas the LTE BTSs shape the traffic per VLAN.

BTS site 2

BTS site 3

GSM BTS

GSM BTS LTE BTS

LTE BTS

VLAN

1Mbps

1Mbps

VLAN

49Mbps

49Mbps

Phys IF

AP

ToP master

AP

L2 network

5Mbps both VLANs 5Mbps both VLANs

Phys IF

h i g H h i g h P C H i g 3 C H E S 2 P C P E S 1 S E

BSC

LTE M LTE U/C/S

ES1 PC High 100Mbps

GSM U/C GSM M

ES2 PC High 5Mbps

5Mbps both VLANs (PAbis CC)

GSM U/C GSM M

ES3 PC High 5Mbps

5Mbps both VLANs (PAbis CC)

100Mbps both VLANs

Figure 13: Shaping for GSM + LTE configuration

4.2.3

VLAN Filtering According to Table 25: VLAN ID in Chapter 2.10: Traffic Aggregation on BTS site, the VLAN IDs as shown in Figure 14: VLAN IDs used in GSM+LTE configuration are used for BTS sites 2 and 3. BTS site 2

BTS site 3

GSM BTS

GSM BTS

503 1003

LTE BTS

502 1002 503 1003 3002 3502

503 1003 3002 3502

LTE BTS

LTE M 3002 LTE U/C/S 3502

AP

AP

ToP master

L2 network

502 1002 503 1003 3002 3502

GSM U/C 1002 GSM M 502 GSM U/C 1003 GSM M 503

Figure 14: VLAN IDs used in GSM+LTE configuration VLAN filtering is applied on the ports used for co-location and chaining. On the port used for backhaul, each VLAN used by the hub or the leaf BTS itself is used again. Therefore, there is no gain in using VLAN filtering on this port. The parameters in the LTE BTSs are configured as shown in Table 36: VLAN filtering in GSM+LTE configuration. Parameter

Backhaul port

Co-location port

Chain port

VLAN_ID

VLAN_ID

n/a

true(1)

true(1)

n/a

501, 1001

n/a

site 1, 2, 3 site 1, 2, 3 site 1

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Parameter

Backhaul port

Co-location port

Chain port

n/a

502, 1002

503, 1003, 3002, 3502

n/a

503, 1003

n/a

site 2

site 3 Table 36: VLAN filtering in GSM+LTE configuration Untagged frames are discarded on the ports where VLAN filtering is applied.

4.2.4

Synchronization In this configuration, RF sharing among GSM and LTE system modules is used. This has an impact on synchronization among the two BTSs on each site. With RF sharing, the LTE BTS has to be clock master; GSM BTS has to be clock slave. The RP3 interface is used for synchronization. The synchronization is summarized in Figure 15: GSM and LTE synchronization. BTS site 3

BTS site 2

GSM BTS

GSM BTS

RP3

RP3

LTE BTS

LTE BTS

IEEE1588 ToP master

L2 network

BTS site 1

BSC

GSM BTS

RP3 LTE BTS

Figure 15: GSM and LTE synchronization Note that a reset of the LTE BTS will cause loss of synchronization for the GSM BTS, which will cause a traffic interruption on the GSM BTS.

4.2.5

BTS site 1 (standalone site) BTS site 1 is not part of a BTS chain. The LTE BTS is used to provide the hub functionality.

BTS site 1

FIQB

GSM BTS LTE BTS

AP FTLB

Figure 16: GSM + LTE BTS site 1 (standalone site) configuration It is assumed that the LTE BTS is connected via optical 1000Base-X to the attachment point. A 1000Base-T connection is used to connect to the GSM BTS. The BTS integrated switch is not used in the GSM BTS, therefore ingress rate limiting is not applicable. Ingress rate limiting is not used in the LTE BTS, because larger bursts (8.5 Mbit) are possible in downlink than can be tolerated by the ingress rate limiter of the BTS integrated switch (8 Mbit).

4.2.6

BTS site 2 (hub site) BTS site 2 is a hub site that relays traffic between the network and another BTS site. The LTE BTS at the site aggregates the traffic both from the leaf BTS site as well as from a co-located BTS; therefore, an additional hop for the traffic of the leaf BTS site is avoided.

BTS site 2

BTS site 3

GSM BTS

FIQB

LTE BTS

AP FTLB

Figure 17: GSM+LTE BTS site 2 (hub site) It is assumed that the LTE BTS is connected via optical 1000Base-X to the attachment point, a 1000Base-T connection is assumed to connect to the leaf BTS nd site. The 2 electrical interface is also configured to 1000Base-T to connect the GSM BTS.

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The QoS aware BTS integrated switch is not used in the GSM BTS, therefore ingress rate limiting is not applicable. To protect the LTE BTS against the injection of too much traffic via the connection between BTS sites 2 and 3, the ingress rate at this interface is limited to 60 Mbps. 7 This is exactly the sum of dimensioned capacity . By limiting the traffic from BTS site 3, there will always be some capacity left for the LTE BTS on site 2, allowing to manage this BTS even in case of an attack. The BTSs on the leaf site generate almost no bursts; therefore there is no problem with the burst size of the ingress rate limiter. The parameter l2IngressRate of this interface is set to RT_60. It is assumed here that it is not possible to inject traffic between the co-located GSM BTS and the LTE BTS nor in downlink between the attachment point and the LTE BTS, therefore ingress rate limiting would not provide a benefit and is not used on these interfaces. The parameter l2IngressRate is set to RT_LINE_RATE.

4.2.7

BTS site 3 (leaf site) BTS site 3 is a leaf site. The LTE BTS is used to provide the hub functionality.

BTS site 3

GSM BTS LTE BTS

BTS site 2

FIQB

AP FTLB

Figure 18: GSM+LTE BTS site 3 (leaf site) Following the configuration of BTS site 2, see Chapter 4.2.6: BTS site 2 (hub site), the LTE BTS is connected via 1000Base-T to the hub BTS site as well as to the colocated GSM BTS. The BTS integrated switch is not used in the GSM BTS, therefore ingress rate limiting is not applicable. Ingress rate limiting is not used in the LTE BTS, because larger bursts (8.5 Mbit) are possible in downlink than can be tolerated by the ingress rate limiter of the BTS integrated switch (8 Mbit).

4.2.8

BTS IP configuration The basic principles as described in Chapter 2.9.1: VLAN usage at BTS site, apply in this configuration as well. Note that the LTE BTSs on BTS site 2 and BTS site 3 are connected to the same VLANs, nevertheless /29 subnets provide a sufficient amount of IP addresses for the BTSs as well as the edge routers.

7

To avoid changes of this parameter in case of future capacity upgrades one could also use a larger value such as limiting the rate to 100 Mbit. This value must be smaller than the capacity of the Ethernet service for LTE.

The Green Energy Controller is connected to the LTE BTS on each site as described in Chapter 2.9.3: IP address for SSE.

4.2.9

Controller site The edge routers separate the BSC site solutions from the needs of the shared mobile backhaul network. There are no specific requirements for the BSC site solution. Recommended BSC site solutions are described in BSC TRANSPORT SITE SOLUTION, RG20 Mother Document, Scenarios and Requirements and BSC TRANSPORT SITE SOLUTION RG20 Daughter Document External L2/L3 Equipment . The shaping of downlink traffic is described in Chapter 4.2.2: Shaping, the routing and HSRP configuration is shown in Chapter 2.9.2.2: Routing configuration with HSRP/VRRP.

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5

WCDMA and LTE This reference configuration describes a configuration for a WCDMA and an LTE RAN over a shared mobile backhaul network. Both RATs use IP/Ethernet for backhaul. No GSM is deployed in this configuration. The main characteristics of the network considered in this case are as follows: 















5.1 5.1.1

Backhaul network overview: The backhaul network provides L2 connectivity between controller site routers and BTS sites. A dedicated Ethernet service with single performance class is deployed per RAT for each BTS chain. The backhaul network is agnostic to the underlying technology used to provide the L2 services. A typical implementation of such a transport service is VPLS using an MPLS based network. Backhaul network sharing: the network is shared by both WCDMA and LTE RAN. There might be additional services using the network, but there is guaranteed capacity allocated to the mobile network. The dimensioning of the guaranteed capacity should follow the mobile network dimensioning. Synchronization: An IEEE1588 master is located on the controller site. The WCDMA BTS on each site is synchronized via IEEE1588. The WCDMA BTS synchronizes the co-located LTE BTS on the same site with SyncE or with an E1 line without traffic. Network redundancy: It is assumed that the transport network features inherent redundancy, transparently protecting the mobile traffic against failures inside the network. Controller site redundancy: Controller site routers are doubled for redundancy. The radio controller connections to the network are redundant, whereas for each BTS the traffic is carried over a single link in the last mile. The redundancy solution for the RNC is the usual, HSRP/VRRP based one. Backhaul network bandwidth: The backhaul network supports bandwidth provisioning for the BTSs. The provisioned bandwidth is provided completely as guaranteed bandwidth. The provisioning of bandwidth is transparent to the mobile network; it is considered part of the network operation. Backhaul network QoS: The traffic in the MBH is treated completely with performance class High. VLAN usage: VLANs are deployed in the backhaul network to separate the BTS broadcast domains and to facilitate mapping of traffic to Ethernet services. At the BTS, management plane is separated to its own VLAN. In this configuration, VLANs are configured to the RNC and the site routers as well.

Recommended Network Configuration Description General configuration In this recommended configuration, dedicated Ethernet services per RAT are used. Voice service is provided mostly by WCDMA. A separate Ethernet service is used for WCDMA. The LTE BTS uses the same VLAN, for both high-priority and low-priority user plane traffic. As the mapping of traffic to Ethernet services is based on VLAN IDs, the highand low-priority user plane traffic has to be carried in a single Ethernet service. This Ethernet service is used to carry also the control and management plane traffic. Each

Ethernet service has a single performance class. It has to be performance class High so that also the LTE voice service can be carried over this Ethernet service. Additionally, the capacity of the Ethernet service has to be provided completely as guaranteed bandwidth that is equals peak bandwidth. To keep the configurations similar for WCDMA and LTE, a single Ethernet service with performance class High is used also for WCDMA. The potential gain of using an Ethernet service with performance class Low for HSPA NRT traffic would be small; this traffic is less than half of the overall traffic volume. The BTSs of one RAT in a chain use the same Ethernet service to reduce the bandwidth requirements for the Ethernet service. BTS site 2

BTS site 3

LTE BTS

LTE BTS WCDMA BTS

AP

WCDMA BTS

ToP master

AP L2 network

RNC

BTS site 1

LTE BTS

S1/Iu

WCDMA BTS

Figure 19: Several Ethernet services with single performance class The bandwidth of the Ethernet services is provided completely as guaranteed bandwidth. For the chain of BTS sites 2 and 3, the bandwidth is dimensioned corresponding to the maximum of peak bandwidth of one BTS and the sum of average bandwidth of both BTSs. The average number for LTE non-GBR user plane is derived from user demand on the air interface. Traffic type

Average [kbps]

Peak [kbps]

LTE GBR user plane (VoIP, QCI1)

n/a

2000

LTE non-GBR user plane

38000

68000

LTE control plane

200

1000


64

1000

IEEE1588

16

16

WCDMA control plane

507

507

WCDMA user plane RT + DCH NRT

3701

3701

WCDMA CCH

66

66

WCDMA user plane HSPA NRT

4418

41200


64

2000

Table 37: LTE and WCDMA traffic amount

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The average amount of traffic of one LTE BTS is 41500 kbps; the peak amount is 72000 kbps. For the chain of LTE BTSs on sites 2 and 3 the Ethernet service has to provide at least 83000 kbps of guaranteed bandwidth, for BTS site 1 a guaranteed bandwidth of 72000 kbps is sufficient. For a WCDMA BTS, there is 8772kbps average amount of traffic and 47490kbps peak amount of traffic. Both for the standalone BTS on site 1 as well as for the chain of BTS on sites 2 and 3, the Ethernet services have to provide a bandwidth of 47490 kbps. The guaranteed bandwidth values are rounded up to provide some headroom for future traffic growth, see Table 38: WCDMA+LTE information rates. Ethernet service

Site

RAT

Performance class

guaranteed bandwidth equal to peak bandwidth [Mbps]

ES1 1

WCDMA

High

50

ES2 1

LTE

High

80

ES3 2+3

WCDMA

High

50

ES4 2+3

LTE

High

100

Table 38: WCDMA+LTE information rates

5.1.2

Feature usage The most relevant features for deploying WCDMA and LTE over a shared backhaul network in this recommended network configuration are listed below.

5.1.2.1

5.1.2.2

WCDMA 







RAN1254 Timing over Packet for BTS Application SW












RAN1769 QoS aware Ethernet switching






RAN2071 Synchronous Ethernet Generation



RAN2440 Fast IP Rerouting

LTE The LTE transport related features are listed below 











5.2 5.2.1









LTE592 Link Supervision with BFD



LTE713 Synchronous Ethernet



LTE866 Fast IP Rerouting

RAN parameters for the configuration General The bandwidth of an Ethernet service is shared only among BTSs of the same radio technology. Different approaches are used in downlink and uplink to share the bandwidth. In uplink, the bandwidth is shared statically among the BTSs and each BTS shapes the traffic per VLAN to the corresponding limit. In downlink direction the bandwidth is shared dynamically; the edge routers shape the aggregated traffic for both BTSs to the capacity of the corresponding Ethernet service. The WCDMA downlink traffic is limited by the edge routers. There is no gain in using the internal flow control of the RNC in addition. Therefore IFC is switched off. The complete bandwidth of the Ethernet services is provided as guaranteed bandwidth. Even for the Ethernet service used by two BTSs, there is more bandwidth available than needed for the GBR bearers of both BTSs. Therefore, CAC and TAC are not used for WCDMA and LTE, respectively. Also, the gain for the WCDMA Ethernet service of using RAN1886 Efficient Transport for small IP packets would be relatively small; therefore this feature is not used in this configuration. In uplink direction the BTSs are configured to not generate bursty traffic such that problems with Ethernet switches with small buffers are avoided. In the downlink direction, the supported burst sizes of the Ethernet services are utilized. The BTS integrated switch have to cope with large bursts, but as all interfaces used provide the same line rate it is possible to forward the data as quickly as it arrives. Some small amount of buffering might be needed due to the X2 traffic among the LTE BTSs in the chain. This traffic has to be aggregated with the downlink traffic for the LTE BTS on the leaf BTS, due to the small amount of X2 and as the BTSs do not send bursty traffic themselves this aggregation does not cause problems. The traffic is aggregated by the integrated switching functionality of the WCDMA BTS. This does not support switching of Ethernet frames larger than 1522 bytes, therefore the support for jumbo frames for LTE cannot be used and IP fragmentation on the S1 and X2 interfaces might occur.

5.2.2

Shaping Uplink shaping is performed in the BTSs; the bandwidth is split statically among the BTS in a chain and among the different VLANs, see Table 39: Uplink shaping for WCDMA and LTE configuration. Parameter WCDMA user, control, synchronizati on plane

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BTS site 1

BTS site 2

BTS site 3

48Mbps

23 Mbps

23 Mbps

1522 bytes

1522 bytes

1522 bytes


Comment

prevent bursts

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Parameter

BTS site 1


LTE user, control plane


BTS site 2

BTS site 3

2 Mbps

2 Mbps

2 Mbps

1522 bytes

1522 bytes

1522 bytes

79 Mbps

49 Mbps

49 Mbps

1522 bytes

1522 bytes

1522 bytes

1 Mbps

1 Mbps

1 Mbps

1522 bytes

1522 bytes

1522 bytes

Comment

prevent bursts

prevent bursts

prevent bursts

Table 39: Uplink shaping for WCDMA and LTE configuration The traffic is shaped in downlink direction at the controller/edge routers to the capacity of the individual Ethernet services. The traffic on the user, control and synchronization plane VLAN and on the management plane VLAN for the BTSs of the same radio technology are shaped together to achieve maximal statistical gain. The schedulers are configured with 1SP and 5WFQ queues as described in Table 14: 1SP+5WFQ scheduler. The shaping configuration is summarized in Figure 20: Shaping for WCDMA + LTE configuration. BTS site2

BTS site3

LTE BTS

LTE BTS

WCDMA BTS

WCDMA BTS

h h i g i g H H P C P C 2 1 E S E S AP

AP

Router1 ToP master

L2 network

RNC Router2

LAN 49Mbps LAN 1Mbps

VLAN 49Mbps VLAN 1Mbps

LAN 23Mbps

VLAN 23Mbps

LAN 2Mbps

VLAN 2Mbps

S1/Iu

LTE U/C/S LTE M

ES2 PC High

100Mbps both VLANs

WCDMA U/C/S WCDMA M

ES1 PC High

50Mbps both VLANs

Figure 20: Shaping for WCDMA + LTE configuration

5.2.3

VLAN Filtering According to Table 25: VLAN IDs in Chapter 2.10: Traffic Aggregation on BTS site, the VLAN IDs as shown in Figure 21: VLAN IDs used in WCDMA + LTE configuration are used for BTS sites 2 and 3.

BTS site2

BTS site3

LTE BTS

LTE BTS

3002 3502

3002 3502

WCDMA BTS

WCDMA BTS 3002 3502 1502 2002

3002 3502 1502 2002

AP

AP 3002 3502 1502 2002

Router1 ToP master

L2 network

LTE U/C/S 3502 LTE M 3002 WCDMA U/C/S 2002 WCDMA M 1502

RNC

S1/Iu

Router2

Figure 21: VLAN IDs used in WCDMA+LTE configuration VLAN filtering is applied on the ports used for co-location and chaining. On the port used for backhaul, each VLAN used by the hub or the leaf BTS itself is used again. Therefore there is no gain in using VLAN filtering on this port. The parameters in the WCDMA BTSs are configured as shown in Table 40: VLAN filtering in WCDMA+LTE configuration.

Parameter

Backhaul port , ADMIT_TAGG ED (1)

site 1, 2, 3

port to co-located LTE BTS

Chain port

ADMIT_TAGGED (1)

ADMIT_TAGGE D (1)

, site 1

2-4094

3001, 3501

n/a

, site 2

2-4094

3002, 3502

1502, 2002, 3002, 3502

, site 3

2-4094

3002, 3502

n/a

Table 40: VLAN filtering in WCDMA+LTE configuration Untagged frames are discarded on the ports. On the ports towards the backhaul network, all VLAN IDs are allowed to ease configuration. The parameters and are not relevant as they apply to untagged frames; nevertheless, the parameter is configured to its default value of 1 and considered in the VLAN ID list for the backhaul port. In the LTE BTS the BTS, integrated Ethernet switch is not used, therefore no VLAN filtering is used either.

5.2.4

Synchronization Where possible, the WCDMA hub BTS synchronizes the LTE leaf BTS with synchronous Ethernet. A hub BTS with an FTIB transport module cannot regenerate SyncE; in this case an additional E1 line is used. An overview for the different sites is shown in Figure 22: Synchronization overview for WCDMA and LTE co-location.

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BTS site 2

BTS site 3

LTE BTS

LTE BTS

E1

SyncE WCDMA BTS (FTLB)

WCDMA BTS (FTIB)

IEEE1588

ToP master

AP

AP L2 network

RNC

BTS site 1

LTE BTS

E1 WCDMA BTS (FTIB)

Figure 22: Synchronization overview for WCDMA and LTE co-location

5.2.5

BTS site 1 (standalone site) This BTS site is not part of a BTS chain. A WCDMA BTS with an FTIB transport module provides the hub functionality.

BTS site 1

FTLB

LTE BTS WCDMA BTS FTIB

AP

Figure 23: WCDMA + LTE BTS site 1 (standalone site) 1000Base-T is used among the BTS, whereas the WCDMA BTS is connected with 1000Base-X to the backhaul. The WCDMA BTS acts as an IEEE1588 slave and synchronizes an additional E1 line, see Table 41: WCMA BTS as IEE1588 slave and Master on E1. The FTIB transport module cannot generate Synchronous Ethernet. Parameter

Value true(1)

Comment Belongs to the BTSSCW managed object

false(0) Top(4)

IEEE1588

Parameter

Value

Comment

1

Not relevant with IEEE1588 (1)

true(1)

Not relevant with IEEE1588 Not relevant with IEEE1588

5 seconds

Not relevant with IEEE1588

1 Table 41: WCDMA BTS as IEEE1588 slave and Master on E1 The LTE BTS is synchronized via an additional E1 line. The WCDMA and the LTE BTS shape their own egress traffic to the values defined in Table 39: Uplink shaping for WCDMA and LTE configuration. The BTS integrated switch in the WCDMA BTS is used for traffic prioritization only see Chapter 2.10: Traffic Aggregation on BTS site. Ingress rate limiting is not used in the WCDMA BTS, because larger bursts (13 Mbit) are possible in downlink than can be tolerated by the ingress rate limiter of the BTS integrated switch (560 kbit). The BTS integrated switch is not used in the LTE BTS, therefore ingress rate limiting is not applicable.

5.2.6

BTS site 2 (hub site) BTS site 2 is a hub site that relays traffic between the network and another BTS site. One of the BTSs at this site aggregates the traffic both from the leaf BTS site as well as from a co-located BTS; therefore an additional hop for the traffic of the leaf BTS site is avoided. The WCDMA BTSs are used to provide the hub functionality, on this specific site the FTLB transport module is used as it provides the necessary amount of Ethernet interfaces.

BTS site 2

BTS site 3

LTE BTS WCDMA BTS

FTLB

AP FTLB

Figure 24: WCDMA + LTE BTS site 2 (hub site)

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It is assumed that the WCDMA BTS is connected via optical 1000Base-X to the attachment point, a 1000Base-T connection is assumed to connect to the leaf BTS nd site. The 2 electrical interface is also 1000Base-T and is used to connect to the LTE BTS. The WCDMA BTS acts as an IEEE1588 slave, regenerating SyncE towards the colocated LTE BTS. Actually, SyncE is also regenerated on the interface towards the chaining BTS and on the backhaul interface, even if it is not used there. IEEE1588 is selected as the only synchronization source. Synchronous Ethernet regeneration is switched on, SSM messages of type ITU are used and sent as untagged Ethernet frames, see Table 42: WCDMA BTS as IEEE1588 slave and SyncE master. Parameter

Value

Comment

true(1)

This BTS synchronizes the LTE BTS

true(1)

SSM as a slow protocol should be untagged (default) IEEE1588

1


1 Not relevant with IEEE1588 true(1)


5seconds


1 Table 42: WCDMA BTS as IEEE1588 slave and SyncE master The LTE BTS is synchronized via Synchronous Ethernet. The WCDMA and the LTE BTS shape their own egress traffic to the values defined in Table 39: Uplink shaping for WCDMA and LTE configuration. The BTS integrated switch in the WCDMA BTS is used for traffic prioritization only see Chapter 2.10. There can be up to 75 Mbps of uplink traffic from BTS site 3. This amount of traffic is larger than the backhaul capacity of the WCDMA BTS on site 2 acting as hub, which is 50 Mbps. Therefore it is not possible to limit the ingress traffic from site 3 such that some transport capacity remains for managing this BTS on site 2. Therefore ingress rate limiting is not used in the WCDMA BTS on site 2 and the parameter is set to

The BTS integrated switch is not used in the LTE BTS, therefore ingress rate limiting is not applicable.

5.2.7

BTS site 3 (leaf site) BTS site 3 is a leaf site. A WCDMA BTS with an FTIB transport module provides the hub functionality.

BTS site 3

LTE BTS

BTS site 2

FTLB

WCDMA BTS

AP FTIB

Figure 25: WCDMA + LTE BTS site 3 (leaf site) Following the configuration of BTS site 2, see Chapter 5.2.6: BTS site 2 (hub site), the WCDMA BTS is connected via 1000Base-T to the hub BTS site; it uses the other electrical 1000Base-T interface to connect to the co-located LTE BTS. Synchronization, uplink shaping, and ingress rate limiting are configured similarly to the standalone BTS site, see Chapter 5.2.5: BTS site 1 (standalone site).

5.2.8

BTS IP configuration BFD triggered static routes are used in the BTS to connect them to both edge routers, see Chapter 2.9.2.1: Routing configuration with BFD-triggered static routes. Note that the WCDMA BTSs on BTS site 2 and BTS site 3 are connected to the same VLANs, nevertheless /29 subnets provide sufficiently many IP addresses for the BTSs as well as the edge routers. Similarly, the LTE BTSs are connected to the same VLANs. The Green Energy Controller is connected to the WCDMA BTS on each site as described in Chapter 2.9.3: IP address for SSE.

5.2.9

Controller site The edge routers separate the RNC site solution from the needs of the shared mobile backhaul network. There are no specific requirements for the RNC site solution. Recommended RNC site solutions are described in Configuring WCDMA and Flexi Direct Transport and RAN1884: Cisco 76xx as RNC Site Router, in Nokia Siemens Networks WCDMA RAN. The shaping of downlink traffic is described in Chapter 5.2.2: Shaping, the routing configuration is shown in Chapter 3.2.1: General.

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References GSM 1. Flexi Multiradio BTS GSM/EDGE System Module (ESMB/C) Description, DN0946883 2. BSS101417: QoS Aware Ethernet Switching DN0988144 3. BSS21454: Packet Abis over Ethernet, BSS21439: Packet Abis Sync. ToP IEEE1588v2, BSS30450: Packet Abis Synchronous Ethernet, and BSS21444: Packet Abis Security, DN0963184 4. BSC TRANSPORT SITE SOLUTION, RG20 Mother Document, Scenarios and Requirements, DN0976611 5. BSC TRANSPORT SITE SOLUTION RG20 Daughter Document External L2/L3 Equipment, DN0976623 6. BSC EDGE Dimensioning, RG20, DN7032469 7. Transport Network Solutions for BSS, RG20, DN7079267 WCDMA 8. Configuring WCDMA and Flexi Direct Transport, RU30, DN70118388 9. Dimensioning WCDMA RAN document, in Nokia Siemens Networks WCDMA RAN, Rel. RU30, System Library 10. RAN1884: Cisco 76xx as RNC Site Router, in Nokia Siemens Networks WCDMA RAN, System Library 11. Impact of Transport Network Impairments on WCDMA Network Performance, DN0983316, Rel. RU20, System Library LTE 12. Configuring LTE RL20 RAN Transport, RL 30, DN0984506 13. Configuring LTE Transport, RL30, DN0984506 14. LTE Traffic Model, RL30, DN0951784 15. LTE Access Dimensioning Guideline, RL 30, DN0951772 Multiradio 16. Backhaul Sharing QoS Guideline, DN09123927 17. IP Transport Monitoring with Standalone Devices, DN09117727 General 18. NSN Green Energy Controller

Glossary

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Acronym

Explanation

AP

Attachment Point

ARP

Allocation and Retention Priority

BBU

Battery Backup Unit

BCSU

BSC Signaling Unit

BSC

Base Station Controller

BTS

Base Transceiver Station

CAC

Call Admission Control

CC

Congestion Control

CESoPSN

Circuit Emulation Service over Packet Switched Network

CS

Circuit Switched

DL

Downlink

DSCP

Differentiated Services Code Point

ES

Ethernet Service

ETP-E

Exchange Terminal for Packet Abis over Ethernet

GBw

Guaranteed Bandwidth

GE

Gigabit Ethernet

GPRS

General Packet Radio Service

GSM

Global System for Mobile Communications

HLR

Home Location Registry

HSPA

High-Speed Packet Access

HSDPA

High-Speed Packet Downlink Access

HSUPA

High-Speed Packet Uplink Access

HSRP

Hot Standby Routing Protocol

IFC

Internal Flow Control

LAN

Local Area Network

LCT

Local Craft Terminal

LMP

Local Management Port

LTE

Long Term Evolution

MBH

Mobile Backhaul


DN09123915 Issue 03

Recommended Configurations for Multiradio Shared Transport

Acronym

Explanation

MPLS

Multiprotocol Label Switching

MTU

Maximum Transmission Unit

NE

Network Element

NRT

Non real-time

OMS

Operation and Maintenance Server

PBw

Peak bandwidth

PC

Performance Class

PCP

Priority Code Point

PS

Packet Switched

QoS

Quality of Service

RAB

Radio Access Bearer

RAN

Radio Access Network

RAT


RNC

Radio Network controller

RT

Real-time

RTSL

Radio Timeslot

SP

Strict Priority

SPI

Scheduling Priority Indicator

SSE

Site Support Equipment

SyncE

Synchronous Ethernet

TAC

Transport Admission Control

THP

Traffic Handling Priority

ToP

Timing over Packet

TRX

Transmitter/receiver

TWAMP

Two-way active measurement protocol

UL

Uplink

VLAN

Virtual LAN

VRRP

Virtual Router Redundancy Protocol

WCDMA

Wideband Code Division Multiple Access

WFQ

Weighted Fair Queuing

Rmd Cnfg Singleran TX Shr

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