UMTS Iub Dimensioning Principle and Procedure V1[1].5-20100901

UMTS Iub Dimensioning Principle and Procedure

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UMTS RNP

For Internal Use Only

Product version Total 15 pages RAN 12.0


Prepared by

UMTS RNP

Date

2010-9-1

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yyyy-mm-dd

Reviewed by

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Huawei Technologies Co., Ltd. All rights reserved

2010-05-17

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Important Notice: Please send us your comments or requests via URNP-

[email protected] . We will improve the quality of the material to meet your requirements ASAP.

Revision Record Date

Version

CR ID

Revision Description

Author

2006-11-30

1.1

Initial transmittal

Xu Haihong

2008-03-29

1.2

Add IP RAN Dimension Part

Xu Haihong

2008-07-14

1.3

根据部分CR对文档进行修改

Xu Haihong

2010-05-17

1.4

Update according to RAN12.0 features

2010-09-01

1.5

Modify service IUB bandwidth

Li Yuesheng Li Yuesheng

Change Request (CR) Record CR ID 1

2

CR CR Originator Date

CR Description

徐登宇

1、、1、、、、、、、、“ATM over E1/T1”、、、、“ATM over IP”、 Accept 2、4.6.2节，就算公共信道带宽时，为什么要乘以3 ？

耿飞

1、在IUB、、、、、、、、、、、、、“IP over ATM” 2、在下一个版本的指导导和工具上，能否直接把 HSDPA Accept 的峰导速率考导导去？

2010-05-17

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Table of Contents 1 Introduction..................................................................................................................................4 2 Iub Dimensioning Procedure ......................................................................................................5 2.1 Iub dimensioning procedure...................................................................................................5 2.2 Iub dimensioning procedure for three main Iub transport scenarios........................... ..........6 2.2.1 Protocol structure comparisons .......................................................................................6 2.2.2 Service Iub bandwidth/overhead......................................................................................7 3 Iub Bandwidth Dimensioning Methodology.................................................................................9 3.1 CS and CS/voIP over HSPA services peak Iub bandwidth ...................................................9 3.2 CS and CS/voIP over HSPA services Average Iub bandwidth.............................................10 3.3 PS Iub bandwidth..................................................................................................................10 3.4 HSUPA Iub bandwidth..........................................................................................................11 3.5 HSDPA Iub bandwidth..........................................................................................................11 3.5.1 Iub bandwidth for average traffic model..........................................................................11 3.5.2 Iub bandwidth for HSPA End-user Experience Rate Bandwidth requirement................11 3.6 Iub bandwidth for CCH and O&M.........................................................................................12 3.6.1 Iub bandwidth for common control channels (CCH).......................................................12 3.6.2 Iub bandwidth for O&M...................................................................................................12 4 Case Study of Iub Bandwidth Dimensioning ............................................................................12 4.1 Input for Iub bandwidth dimensioning...................................................................................12 4.2 CS and CS over HSPA services peak Iub bandwidth .........................................................13 4.3 CS and CS over HSPA services Average Iub bandwidth.....................................................13 4.4 R99 PS Iub bandwidth..........................................................................................................14 4.5 HSDPA Iub bandwidth..........................................................................................................14 4.6 Iub bandwidth for MBMS, CCH and O&M............................................................................14 4.6.1 Iub bandwidth MBMS......................................................................................................14 4.6.2 Iub bandwidth for CCH....................................................................................................14 4.6.3 Iub bandwidth for O&M...................................................................................................14 4.7 Total Iub bandwidth ..............................................................................................................15

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UMTS Iub Dimensioning Principle and Procedure Abstract: This article presents an overview of UMTS Iub dimensioning principle and procedure. It briefly introduces the usage of multidimensional ErlangB model in Iub dimensioning of CS and CS/VoIP over HSPA services and that of the best effort characteristic in Iub dimensioning of PS&HSPA services. Dimensioning methods based on different Iub transport techs, like ATM and IP are introduced.

1 Introduction Iub is the interface between RNC and NodeB. There are mainly three kinds of Iub transport scenarios: ATM over E1/T1, IP over E1/T1 and IP over Ethernet. Figure 1 and Figure 2 illustrates the scenario of ATM/IP over E1/T1 and IP over Ethernet.

Figure 1 ATM/IP over E1/T1

Figure 2 IP over Ethernet

The purpose of Iub dimensioning is to estimate the required Iub bandwidth and the corresponding number of E1 pairs or IP transport bandwidth. This document is organized as follows: Section 1 is the introduction; Section 2 introduces the Iub dimensioning principle and procedure and compares the protocol structure and Iub overhead for ATM/IP over E1/T1 and IP over Ethernet; Section 3 introduces the detailed procedure of Iub bandwidth dimensioning for services, CCH and O&M; Section 4 gives a case study for IP over Ethernet transmission mode.

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2 Iub Dimensioning Procedure 2.1

Iub dimensioning procedure

For the multi-services in UMTS, Huawei has carried out in-depth research in the field of multi-service network dimensioning and adopts multidimensional ErlangB model to estimate the Iub bandwidth of CS, CS/VoIP over HSPA multi-services. Apart from services bandwidth, Iub bandwidth dimensioning includes calculation of Iub bandwidth occupied by MBMS, common channels and O&M. Figure 3 shows the Iub dimensioning procedure.

Input Subscribers Subs per NodeB

Iub Dimensioning

Output

CS, CS/VoIP over HSPA Iub Peak Bandwidth Iub Bandwidth

CS Traffic Voice Traffic VP Traffic

CS/VoIP over HSPA Traffic GoS Requirements

CS, CS/VoIP over HSPA Iub Average Bandwidth MAX

PS Iub Bandwidth HSPA Iub Bandwidth

Service Iub Bandwidth

PS Traffic PS64 Throughput PS128 Throughput PS384 Throughput

MAX

HSPA End-user Experience Rate Bandwidth

PS Retransmission MBMS Iub Bandwidth HSPA Traffic Common Channel Bandwidth MBMS Channel Number

O&M Bandwidth

Figure 3 Iub dimensioning procedure

For mixed CS, CS/VoIP over HSPA, PS and HSPA services Iub bandwidth dimensioning, best effort characteristic of PS and HSPA is used. In other words, the spare part of Iub bandwidth which is not used by CS services can be utilized by PS and HSPA services. Figure 4 illustrates sharing of Iub bandwidth by CS, CS/VoIP over HSPA, PS and HSPA.

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Total Bandwidth PS & HSPA Occupied Bandwidth

CS, CS/VoIP over HSPA Peak Bandwidth

CS, CS/VoIP over HSPA Average Bandwidth

CS, CS/VoIP over HSPA Occupied Bandwidth

CCH & MBMS Bandwidth O & M Bandwidth Time Figure 4 CS, CS/VoIP over HSPA and PS sharing resource

Therefore, the total Iub bandwidth can be obtained through the following formula: IubTotal

=

Max[( Max[ IubCS ,CS / VoIPoverHS PA _ Peak , ( Iub PS _ Avg + IubCS ,CS / VoIPoverHS PA _ Avg + Iub HSPA )]),

Iub HSPA _ End

used _ Experience _ Rate

−

] + Iub MBMS + IubCCH

IubO & M

+

The ultimate Iub configuration is decided by the larger one of uplink and downlink Iub bandwidth.

2.2

Iub dimensioning procedure for three main Iub transport scenarios

2.2.1 Protocol structure comparisons The Iub dimensioning procedures given in Figure 3 is applicable for ATM over E1/T1, IP over E1/T1 and IP over Ethernet. In other words, the dimensioning procedure for different Iub transport scenarios are the same though the Iub overheads may varies. Figure 5 shows the protocol structure of three main Iub transport scenarios. From the protocol structure, it can be seen that the service Iub overheads for three main Iub transport scenarios are: 

FP overhead, AAL2 overhead and ATM overhead for ATM over E1/T1



FP overhead, UDP/IP overhead and PPP overhead for IP over E1/T1



FP overhead, UDP/IP overhead and MAC overhead for IP over Ethernet

On the other hand, Only ATM over E1/T1 has ALCAP protocol layer. 2010-05-17

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Figure 5 Protocol Structure of ATM,IP over E1/T1 and IP over Ethernet

2.2.2 Service Iub bandwidth/overhead Based on the protocol structure, the Iub bandwidth/overhead for R99, CS/VoIP over HSPA and HSPA service could be calculated and the results are given in Table1.

Table1 R99, CS/VoIP over HSPA service Iub bandwidth

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Notes: The Iub bandwidth per link in above table already considered: 1) The activity factor of AMR12.2k and CS/VoIP over HSPA is 0.65, and that of the other services is 1; 2) The Iub bandwidth occupied by SRB (3.4kbps)is included and the SRB activity factor is 0.1; 3) The Duty Ratio of CS/VoIP over HSPA is 0.1.

Table2 HSPA service Iub Overhead

Notes: 1) Terminal Type 1: supports HSDPA( lower than 14.4Mbps) and phase 1 / phase 2 HSUPA( 1.96Mbps or 5.76Mbps); 2) Terminal Type 2: supports 64QAM or MIMO or 64QAM+MIMO or DC-HSDPA in downlink, and 16QAM in uplink.

Table3 MBMS/O&M/CCH Iub bandwidth

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3 Iub Bandwidth Dimensioning Methodology 3.1

CS and CS/voIP over HSPA services peak Iub bandwidth

CS and CS/voIP over HSPA services peak Iub bandwidth is calculated by multidimensional ErlangB algorithm in Huawei. Multidimensional ErlangB can estimate the respective blocking probability of various CS and CS/voIP over HSPA services. Under a fixed Iub bandwidth, different services have different blocking probabilities, which depend on their Iub bandwidth usages. Multidimensional ErlangB model is illustrated in Figure 6.

Figure 6 Multidimensional ErlangB model

The resource is shared by all services in multidimensional ErlangB model, which takes good advantage of the fact that the probability of simultaneous bursts from many independent traffic sources is very small. The following figure illustrates the gain when the resource is shared compared to when the resource is partitioned.

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Figure 7 Partitioning Resources vs. Resources Shared

Once we know the GoS requirement of CS and CS/voIP over HSPA services, the CS and CS/voIP over HSPA traffic per NodeB (after considering soft handover ratio) and the service Iub bandwidth, we can calculate the CS and CS/voIP over HSPA services peak Iub bandwidth using multidimensional ErlangB 、 MDE 、 model. This idea is shown in Figure 8. Note: Iub factors means Iub bearer bandwidth including FP, AAL2 and ATM or IP overhead for service i.

Traffic & Service Iub Bandwidth

GoS Requirements

MDE

Peak Iub Bandwidth Figure 8 Estimate peak Iub bandwidth using multidimensional ErlangB model

3.2

CS and CS/voIP over HSPA services Average Iub bandwidth Of course, the average Iub bandwidth for CS and CS/voIP over HSPA services can also be obtained, which does not guarantee the GoS requirements. The formula below is used to calculate CS and CS/voIP over HSPA services average bandwidth: IubCS and CS/ voIP over HSPA_Avera ge

=

∑TrafficPer NodeB

i

* (1 + RSHO ) * R Iub _ i

i

RSHO : Soft handover overhead which does not include softer handover; R Iub _ i

: Iub bandwidths for CS and CS/voIP over HSPA service I, shown in Figure 5Table1.

3.3 PS Iub bandwidth The calculation for PS Iub bandwidth is almost the same as that for CS and CS/voIP over HSPA services average Iub bandwidth except that PS traffic calculation should also 2010-05-17 All rights reserved Page 10 , Total15


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consider the PS characteristics, e.g. PS burstiness, retransmission. The formula below is used to calculate PS Iub bandwidth: Iub PS _ Average

∑TrafficPer NodeBi * (1

R SHO ) * (1

R Burst ) * (1

RRe trans ) * R Iub _ i

i

RRe trans

R Burst

3.4

: Retransmission factor of PS services, which is equal to BLER/(1-BLER);

: Burst ratio of PS services and this parameter reflects the Qos requirement of PS services.

HSUPA Iub bandwidth HSUPA usually bears Best Effort (BE) services; the calculation procedure of Iub bandwidth for HSUPA is almost same as that for PS. HSUPA Iub bandwidth is calculated by the below formula:

Iub HSUPA

TrafficPer NodeB * (1 R SHO ) * (1 R Burst ) * (1 RRe trans ) * (1

R Iub _ overhead :

3.5

R Iub _ overhead )

HSUPA service Iub Overhead, shown in Figure 5Table2.

HSDPA Iub bandwidth

3.5.1 Iub bandwidth for average traffic model The calculation procedure of Iub bandwidth for HSDPA is almost same as that for HSUPA. However, it should be noted that HSDPA does not support SHO and therefore there is no Iub SHO overhead for HSDPA. HSDPA Iub bandwidth is calculated by the below formula: Iub HSDPA R Iub _ overhead :

=

TrafficPer NodeB * (1 + R Burst ) * (1 + RRe trans ) * (1 + R Iub _ overhead )

HSDPA service Iub Overhead, shown in Figure 5Table2.

3.5.2 Iub bandwidth for HSPA End-user Experience Rate Bandwidth requirement If HSPA End-user Experience Rate Bandwidth such as 3.6Mbps and 7.2Mbps is given, the Iub bandwidth needed by peak rate can be calculated by the following formula: Iub HSDPA _ Peak PeakRatePerNodeB * (1 RRe trans ) * (1

R Iub _ overhead )

It should be noted that the PeakRatePerNodeB is the application layer rate and the relationship between application layer rate and physical layer rate is given in the following table:

Table1 Physical layer rate & application layer rate

Physical Layer Rate 2010-05-17

Application Layer Rate

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3.6Mbps 7.2Mbps 14.4Mbps

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3.2Mbps 6.4Mbps 12.7Mbps

Notes: Since peak rate is used for Iub calculation, there is no need to consider additional burst ratio;

3.6

Iub bandwidth for CCH and O&M

3.6.1 Iub bandwidth for common control channels (CCH) Iub bandwidth for common channel mainly includes FACH and PCH for downlink while RACH for uplink for one cell. The Iub bandwidth for downlink CCH depends on the configurations of FACH and PCH. FACH and PCH are mapped onto the same physical channel S-CCPCH. Generally, the typical configuration of RACH and S-CCPCH are both one for each cell. Herein, common Channels also includes NBAP, ALCAP consuming Iub bandwidth (For IP transport, there is no ALCAP signaling). As the services speed gets bigger, the ratio of Iub bandwidth consumed by NBAP, ALCAP gets so lower as to be ignored.

3.6.2 Iub bandwidth for O&M O&M Iub bandwidth is configurable and the typical recommended value is 64kbps for both uplink and downlink for one NodeB.

4 Case Study of Iub Bandwidth Dimensioning This chapter gives a case study for IP over Ethernet Iub bandwidth calculations. Since the uplink and downlink Iub bandwidth calculation procedures are the same, only downlink Iub bandwidth calculations are shown.

4.1

Input for Iub bandwidth dimensioning

The Iub bandwidth calculation is exemplified with a case study using the following traffic model given in Table2 and the HSPA End-user Experience Rate Bandwidth (peak rate) requirement of HSDPA is 7.2Mbps. Table2 Traffic Model

Traffic Model (Single User @ Busy Hour) Bearers Uplink Downlink AMR12.2k (Voice) 10 mErl 10 mErl CS64k、Video、 1 mErl 1 mErl PS64k 1266 kbits 4227 kbits PS128k 0 456 kbits 2010-05-17

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GoS 2% 2% N/A N/A Page 12 , Total15


PS384k HSPA CS over HSPA

0 3797 kbits 1 mErl

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380kbts 15188 kbits 1 mErl

N/A N/A 2%

Assumption: 

NodeB configuration S111



Subscribers number per NodeB is 1000



Soft HO ratio is 20%



PS traffic burst ratio is 20%



HSDPA traffic burst ratio is 20%



HSDPA End-user experience rate: 7.2Mbps in Physical Layer, 6.4Mbps in application Layer

4.2



HSDPA average Rate: 1920kpbs



HSDPA UE Type: Type 1



Retransmission ratio of PS services is 1%



Retransmission ratio of HSPA is 1%



MBMS channel number: 1 (128k)

CS and CS over HSPA services peak Iub bandwidth

For DL direction: Voice traffic:

=

0.01 Erl / user ×1000user / NodeB =10 Erl

Video call traffic:

=

0.001 Erl / user ×1000user / NodeB

CS over HSPA traffic:

=

1 Erl

=

0.001Erl/u ser ×1000user/N odeB

=

1Erl

Using MDE, the peak Iub bandwidth for CS and CS over HSPA services is IubCS and CS over HSPA servic es_P eak

4.3

=

0.58Mbps

CS and CS over HSPA services Average Iub bandwidth

Average Iub needed by Voice: =

10Erl*(1 + 20%)*13.7/ 1024

=

0.16Mbps

Average Iub needed by Video Call: =

1Erl*(1 + 20%)*86*7/ 1024

=

0.10Mbps

Average Iub needed by CS over HSPA: =

1Erl*(1 + 20%)*13.9/ 1024

=

0.02Mbps

Average Iub needed by CS and CS over HSPA call is: IubCS and CS over HSPA services _Average

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= 0.16 +0.10 +0.02 = 0.28

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Mbps

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R99 PS Iub bandwidth

Average Iub needed by PS64k: =

1000*4227 64*3600

* ( 1 + 20% )* ( 1 + 20% )* ( 1 + 1% )*89.7 /1024

=

2.39Mbps


1000*456 128*3600

* ( 1 + 20% )* ( 1 + 20% )* ( 1 + 1% )*156.7/1024

=

0.22Mbps

=

0.18Mbps


1000*380 384*3600

* ( 1 + 20% )* ( 1 + 20% )* ( 1 + 1% )*447.7/1024

Average Iub needed by PS Services: Iub PS service s_Average

4.5

=

2.39

+

0.22

+

0.18

=

2.79Mbps

HSDPA Iub bandwidth

Average Iub bandwidth needed by HSDPA:

Iub HSDPA =

1000*15188 *( 1 + 20%)*( 1 + 1%) 3600

*( 1 + 20%) /1024 = 6.00Mbp

Since the 7.2Mbps physical layer rate corresponding to application layer rate 6.4Mbps, Peak HSDPA Iub bandwidth for each NodeB is:

Iub HSDPA _ Peak = 6400* ( 1 + 1%)* ( 1 + 20%) /1024 = 7.59Mbps

4.6

Iub bandwidth for MBMS, CCH and O&M

4.6.1 Iub bandwidth MBMS Average Iub needed by MBMS: Iub MBMS = 1*145/1024

=

0.142Mbpss

4.6.2 Iub bandwidth for CCH The typical Iub bandwidth of CCH (including NBAP) for S111 is IubCCH_DL

=

0.213Mbps

4.6.3 Iub bandwidth for O&M The Iub bandwidth of O&M is 64kbps.

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4.7

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Total Iub bandwidth

DL total Iub bandwidth is: Iubtotal

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Max{Max[0.58M ,(0.28 M + 2.79M + 6.00M)],7.59M} + 0.142 + 0.213 + 0.064

=

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=

9.49 Mb

UMTS Iub Dimensioning Principle and Procedure V1[1].5-20100901

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