Capacity Monitoring Guide

eRAN7.0

Capacity Monitoring Guide

Issue

02

Date

2014-05-27

HUAWEI TECHNOLOGIES CO., LTD.

Copyright © Huawei Technologies Co., Ltd. 2014. All rights reserved. No part of this document may be reproduced reproduced or transmitted in any form or by any means means without prior written consent of Huawei Technologies Co., Ltd.

Trademarks and Permissions and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd. All other trademarks and trade names mentioned in this document are the property of their respective holders.

Notice The purchased products, services and features are stipulated by the contract made between Huawei and the customer. All or part of the products, services and features described in this document may not be within the purchase scope or the usage scope. Unless otherwise specified in the contract, all statements, information, and recommendations in this document are provided "AS IS" without warranties, guarantees or representations of any kind, either express or implied. The information in this document is subject to change without notice. Every effort has been made in the preparation of this document to ensure accuracy of the contents, but all statements, information, and recommendations in this document do not constitute a warranty of any kind, express or implied.

Huawei Technologies Co., Ltd. Address:

Huawei Industrial Base Bantian, Longgang Shenzhen 518129 People's Republic of China

Website:

http://www.huawei.com

Email:

[email protected]

Issue 02 (2014-05-27)

Huawei Proprietary and Confidential Copyright © Huawei Technologies Co., Ltd.

i

Copyright © Huawei Technologies Co., Ltd. 2014. All rights reserved. No part of this document may be reproduced reproduced or transmitted in any form or by any means means without prior written consent of Huawei Technologies Co., Ltd.

Trademarks and Permissions and other Huawei trademarks are trademarks of Huawei Technologies Co., Ltd. All other trademarks and trade names mentioned in this document are the property of their respective holders.

Notice The purchased products, services and features are stipulated by the contract made between Huawei and the customer. All or part of the products, services and features described in this document may not be within the purchase scope or the usage scope. Unless otherwise specified in the contract, all statements, information, and recommendations in this document are provided "AS IS" without warranties, guarantees or representations of any kind, either express or implied. The information in this document is subject to change without notice. Every effort has been made in the preparation of this document to ensure accuracy of the contents, but all statements, information, and recommendations in this document do not constitute a warranty of any kind, express or implied.

Huawei Technologies Co., Ltd. Address:

Huawei Industrial Base Bantian, Longgang Shenzhen 518129 People's Republic of China

Website:

http://www.huawei.com

Email:

[email protected]

Issue 02 (2014-05-27)


i

eRAN7.0 Capacity Monitoring Guide

About This Document

About This Document Purpose Growing traffic in mobile networks requires more and more resources. Lack of resources will affect user experience. This document provides guidelines on LTE FDD capacity monitoring including details on how to identify resource allocation problem and on how to monitor network resource usage. Capacity monitoring provides data reference for network reconfiguration and capacity expansion and enables maintenance personnel to take measures before resources insufficiency insufficiency affects affects network QoS and user experience. NOTE 

For definitions of the man-machine language (MML) commands, parameters, alarms, and performance performance counters counters mentioned mentioned in this document, document, see see the "Operation "Operation and Maintenance" Maintenance" part part in 3900 Series LTE eNodeB Product Documentation for eNodeB base station, BTS3202E Product Documentation Documentation for BTS3202E BTS3202E base base station, and and BTS3203E LTE LTE Product Product Documentation Documentation for BTS3203E base station. station.



For the BTS3202E and the BTS3203E LTE, the main control unit, transmission unit, and baseband unit share the CPU because they are integrated into the same board, called BTS3202E board or BTS3203E LTE board. The main control board and the baseband board mentioned in this document correspond to the BTS3202E board or BTS3203E LTE board, and the CPU usage of the main control board corresponds to that of the BTS3202E board or BTS3203E LTE board.



This document is not applicable to scenarios with large capacity and heavy traffic. For guidelines in such scenarios, contact Huawei technical support.

Product Versions The following table lists the product version related to this document.

Product Name

Solution Version

BTS3900



SRAN9.0



eRAN7.0



SRAN9.0



eRAN7.0



eRAN TDD 7.0



SRAN9.0

BTS3900A

Product Version V100R009C00

BTS3900L BTS3900AL DBS3900

BTS3202E

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About This Document

Product Name

Solution Version

BTS3203E LTE

eRAN7.0

Product Version

Intended Audience This document is intended for:  

Field engineers Network planning engineers

Change History This section describes changes in each issue of this document. 

02 (2014-05-27)



01 (2014-04-26)



Draft B (2014-03-31)



Draft A (2014-01-20)

02 (2014-05-27) This is the second commercial release. Compared with issue 01 (2014-04-26), issue 02 (2014-05-27) includes the following changes.

Change Type

Changed Part

Change Description

Modification

Section 2.8.1 "Monitoring Principles"

Modified the maximum number of paging messages that a 3900 series base station can be sent each second.

01 (2014-04-26) This is the first commercial release. Compared with draft B (2014-03-31), issue 01 (2014-04-26) includes the following changes. Change Type

Changed Part

Change Description

Modification

Section 2.9.2 “Monitoring Methods”

Modified the formula of “Percentage of times that the main-control-board CPU usage reaches or exceeds a preconfigured threshold (85%). ”

Section 2.10.2 “Monitoring Methods”

Modified the formula of “Percentage of times that the baseband processing unit CPU usage reaches or exceeds a preconfigured threshold (85%).”

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About This Document

Draft B (2014-03-31) This is the second draft. Compared with draft A (2014-01-20), draft B (2014-03-31) includes the following changes. Change Type

Changed Part

Change Description

Addition

Section 2.3 "Synchronized User Capacity Usage"

Added the details about how to check whether the synchronized user capacity of a cell is sufficient.

Section 2.7 "Traffic Volume License Usage"

Added the details about how to check whether the licensed eNodeB traffic volume is sufficient.

Modification

Section 2.1 "Introduction" Modified Table 2-1. Section 2.2 "Downlink User Perception"

Modified the suggested measures.

Section 2.5 "PDCCH Resource Usage"

Modified the monitoring principles, monitoring methods, and suggested measures.

Section 2.8 "Paging Resource Usage"



Deleted the monitoring item L. Paging.Dis.Num.



Added suggested measures for the core network.

Section 2.9 "Main-Control-Board CPU Usage"

Modified the suggested measures.

Section 2.11 "Transport Resource Group Usage"

Cancel the monitoring of packet loss rate.

Draft A (2014-01-20) This is the first draft.

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Contents

Contents About This Document .................................................................................................................... ii 1 Overview......................................................................................................................................... 1 1.1 Network Resources .......................................................................................................................................... 1 1.2 Capacity Monitoring Methods.......................................................................................................................... 3

2 Capacity Monitoring..................................................................................................................... 4 2.1 Introduction ........................................................ .............................................................. ................................ 4 2.2 Downlink User Perception ............................................................................................................................... 6 2.2.1 Monitoring Principles ............................................................................................................................. 6 2.2.2 Monitoring Methods ............................................................................................................................... 6 2.2.3 Suggested Measures ........................................................................................................... ..................... 7 2.3 Synchronized User Capacity Usage ................................................... .............................................................. 7 2.3.1 Monitoring Principles ............................................................................................................................. 7 2.3.2 Monitoring Methods ............................................................................................................................... 7 2.3.3 Suggested Measures ........................................................................................................... ..................... 8 2.4 PRACH Resource Usage ......................................................... ............................................................... .......... 8 2.4.1 Monitoring Principles ............................................................................................................................. 8 2.4.2 Monitoring Methods ............................................................................................................................... 8 2.4.3 Suggested Measures ........................................................................................................... ..................... 9 2.5 PDCCH Resource Usage ......................................................... ............................................................... .......... 9 2.5.1 Monitoring Principles ............................................................................................................................. 9 2.5.2 Monitoring Methods ............................................................................................................................... 9 2.5.3 Suggested Measures ........................................................................................................... ................... 11 2.6 Connected User License Usage .......................................................... ............................................................ 11 2.6.1 Monitoring Principles ........................................................................................................................... 11 2.6.2 Monitoring Methods ............................................................................................................................. 11 2.6.3 Suggested Measures ........................................................................................................... ................... 11 2.7 Traffic Volume License Usage ........................................................... ............................................................ 12 2.7.1 Monitoring Principles ........................................................................................................................... 12 2.7.2 Monitoring Methods ............................................................................................................................. 12 2.7.3 Suggested Measures ........................................................................................................... ................... 12 2.8 Paging Resource Usage ........................................................... ............................................................... ........ 12 2.8.1 Monitoring Principles ........................................................................................................................... 12

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Contents

2.8.2 Monitoring Methods ............................................................................................................................. 12 2.8.3 Suggested Measures ........................................................................................................... ................... 13 2.9 Main-Control-Board CPU Usage ..................................................................................... .............................. 13 2.9.1 Monitoring Principles ........................................................................................................................... 13 2.9.2 Monitoring Methods ............................................................................................................................. 13 2.9.3 Suggested Measures ........................................................................................................... ................... 13 2.10 Baseband Processing Unit CPU Usage ........................................................................................................ 14 2.10.1 Monitoring Principles ......................................................................................................................... 14 2.10.2 Monitoring Methods ........................................................................................................................... 14 2.10.3 Suggested Measures ......................................................................................................... ................... 14 2.11 Transport Resource Group Usage ................................................................ ................................................. 15 2.11.1 Monitoring Principles .............................................................. ............................................................ 15 2.11.2 Monitoring Methods ................................................................ ............................................................ 16 2.11.3 Suggested Measures ......................................................................................................... ................... 16 2.12 Ethernet Port Traffic .............................................................. ............................................................... ........ 16 2.12.1 Monitoring Principles ......................................................................................................................... 16 2.12.2 Monitoring Methods ........................................................................................................................... 17 2.12.3 Suggested Measures ......................................................................................................... ................... 17

3 Resource Allocation Problem Identification ......................................................................... 19 3.1 Resource Congestion I ndicators ......................................................... ............................................................ 19 3.1.1 RRC Resource Congestion Rate ........................................................................................................... 20 3.1.2 E-RAB Resource Congestion Rate .................................................................................... ................... 20 3.2 Resource Allocation Problem Identification Process ............................................ ......................................... 20

4 Related Counters ......................................................................................................................... 22

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1 Overview

1

Overview

This chapter describes the types of network resources to be monitored and the method of performing capacity monitoring.

1.1 Network Resources Figure 1-1 shows the network resources to be monitored. Figure 1-1 Network resources to be monitored

Table 1-1 describes the types of network resources to be monitored and impacts of resource insufficiency on the system.

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1 Overview

Table 1-1 Network resources Resource Type

Meaning

Impact of Resource Insufficiency on the System

Monitoring Item

Cell resources

Physical resource blocks (PRBs)

Bandwidth consumed on the air interface

Users may fail to be admitted, and experience of admitted users is affected.

Downlink User Perception

Synchronized user capacity

Maximum number of synchronized users in a cell

User experience is affected.

Synchronized User Capacity Usage

Physical random access channel (PRACH) resources

Random access preambles carried on the PRACH

Access delays are prolonged, or even access attempts fail.

PRACH Resource Usage

Physical downlink control channel (PDCCH) resources

Downlink control channel resources

Uplink and downlink scheduling delays are prolonged, and user experience is affected.

PDCCH Resource Usage

Connected user license

Maximum permissible number of users in RRC_CONNECTED mode

New services cannot be admitted, and experience of admitted users is affected.

Connected User License Usage

Traffic volume license

Maximum traffic volume in an eNodeB

User experience and customer income are affected.

Traffic Volume License Usage

Paging resources

eNodeB paging capacity

Paging messages may be lost, affecting user experience.

Paging Resource Usage

Main-control-board CPU

Processing capability of the main control board of the eNodeB

KPIs deteriorate.

Main-Control-Board CPU Usage

Baseband processing unit CPU

Processing capability of the baseband processing unit

KPIs deteriorate.

Baseband Processing Unit CPU Usage

Transport resource groups

eNodeB logical transport resources

Packets may be lost, affecting user experience.

Transport Resource Group Usage

eNodeB resources

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Resource Type

Ethernet ports

1 Overview

Meaning

Impact of Resource Insufficiency on the System

Monitoring Item

eNodeB physical transport resources

Packets may be lost, affecting user experience.

Ethernet Port Traffic

1.2 Capacity Monitoring Methods Capacity monitoring can be implemented using the following two methods: 



Daily monitoring for prediction: Counters are used to indicate the load or usage of various types of resources on the LTE network. Thresholds for resource consumption are specified so that preventive measures such as reconfiguration and expansion can be taken to prevent network congestion when the consumption of a type of resource continually exceeds the threshold. For details, see chapter 2 "Capacity Monitoring." Problem-driven analysis: This method helps identify whether a problem indicated by counters is caused by network congestion through in-depth analysis. With this method, problems can be precisely located so that users can work out a proper network optimization and expansion solution. For details, see chapter 3 "Resource Allocation Problem Identification." 

Thresholds defined for capacity monitoring in this document are generally lower than those for alarm triggering so that risks of resource insufficiency can be detected as early as possible.



Thresholds given in this document apply to networks experiencing a steady growth. Thresholds are determined based on product specifications and experiences in working with existing networks. For example:



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-

The CPU usage threshold 60% is specified based on the CPU flow control threshold 80%.

-

The eNodeB's connected user license usage threshold 60% is specified based on the peak-to-average ratio (about 1.5:1). When the average usage reaches 60%, the peak usage approaches 100%. Threshold determining considers both average and peak values.

Telecom operators are encouraged to formulate an optimization solution for resource capacity based on prediction and analysis for networks that are experiencing fast development, scheduled to deploy new services, or about to employ new charging plans. If you require services related to resource capacity optimization, such as prediction, evaluation, optimization, reconfiguration, and capacity expansion, contact Huawei technical support.


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2 Capacity Monitoring

2

Capacity Monitoring

This chapter describes monitoring principles and methods, as well as related counters, of all types of service resources. Information about how to locate resource bottlenecks and the related handling suggestions are also provided. Note that resource insufficiency may be determined by usage of more than one type of service resource. For example, a resource bottleneck can be claimed only when both connected user license usage and main-control-board CPU usage exceed the predefined thresholds.

2.1 Introduction You need to determine busy hours of the system for accurate monitoring of counters. You are advised to define busy hours as a period when the system or a cell is undergoing the maximum resource consumption of a day.

Table 2-1 describes types of resources to be monitored, thresholds, and handling suggestions. Table 2-1 Types of resources to be monitored, thresholds, and handling suggestions

Resource Type

Monitoring Item

Conditions

Handling Suggestions

Downlink User Perception

Downlink PRB usage ≥ 70% and downlink user-perceived rate < 2 Mbit/s (default value, user-configurable)

Optimize RF performance, expand the cell bandwidth, add carriers or eNodeBs.

PRACH Resource Usage

Usage of preambles for contention- based access ≥ 75%

Enable the backoff algorithm for the PRACH.

Usage of preambles for non-contention- based access ≥ 75%

Enable the PRACH resource adjustment algorithm and reuse of dedicated preambles.

CCE usage ≥ 80%

Set PDCCH Symbol Number Adjust Switch to ON(On) .

Cell resources

PDCCH Resource Usage

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PDCCH Symbol Number Adjust Switch is set to OFF(Off)


4


Resource Type

Monitoring Item


Conditions PDCCH Symbol Number Adjust Switch is set to ON(On) , and uplink or downlink PRB usage ≥ 70%

Handling Suggestions Take one of the following measures: 

Add carriers.



Split cells.



Optimize radio frequency (RF) performance .

Take one of the following measures: Synchronized User Capacity Usage

Connected User License Usage

Traffic Volume License Usage

Connected user capacity usage in a cell ≥ 60%

Conne cted user license usage ≥ 60%

Optimize parameters.



Optimize RF performance



Expand the cell bandwidth.



Add carriers.



Split cells.

Main-control-board CPU usage < 60%

Add licenses.

Main-control-board CPU usage ≥ 60%

Add eNodeBs.

Traffic volume license usage of an eNodeB ≥ 80%

Increase the licensed traffic volume. Take one of the following measures:

Paging Resource Usage

Percentage of paging messages received on the S1 interface ≥ 60%

eNodeB resources





Decrease the number of cells in the tracking area list (TAL) that the congested cell belongs to.



Adjust the paging policy of the core network to reduce signaling overhead.



Main-Control-Board CPU Usage





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Average main-control-board CPU usage ≥ 60%, or Percentage of times that the CPU usage reaches or exceeds 85% ≥ 5%


If the core network is provided by Huawei, enable the precise paging function.

Take one of the following measures: 

Make the loads balance.



Use boards with higher specifications to replace old boards.



Add eNodeBs.

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Resource Type

Monitoring Item Baseband Processing Unit CPU Usage


Conditions





Transport Resource Group Usage





Ethernet Port Traffic

Average baseband processing unit CPU usage ≥ 60%, or Percentage of times that the CPU usage reaches or exceeds 85% ≥ 5%

Proportion of average transmission rate to configured bandwidth ≥ 80%, or Proportion of maximum transmission rate to configured bandwidth ≥ 90%

Proportion of average transmission rate to allocated bandwidth ≥ 70% or Proportion of maximum transmission rate to allocated bandwidth ≥ 85%

Handling Suggestions Take one of the following measures: 

Add boards.



Use boards with higher specifications to replace old boards.



Make the inter-BBP loads balance.

Expand the bandwidth of the transport resource group.

Expand the eNodeB transmission capacity.

2.2 Downlink User Perception 2.2.1 Monitoring Principles Growing traffic leads to a continuous increase in PRB usage. When the PRB usage approaches to 100%, user-perceived rates will decrease. As downlink is a major concern in an LTE network, this document describes only how to monitor downlink user perception. NOTE

The uplink user perception can be monitored using the same way.

2.2.2 Monitoring Methods The following items are used in monitoring this case: 

Downlink PRB usage L.ChMeas.PRB.DL.Used.Avg/L.ChMeas.PRB.DL.Avail x 100%



Downlink user-perceived rate (Mbit/s) = L.Thrp.bits.DL/L.Thrp.Time.DL/1000

where

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

L.ChMeas.PRB.DL.Used.Avg indicates the average number of used downlink PRBs.



L.ChMeas.PRB.DL.Avail indicates the number of available downlink PRBs.



L.Thrp.bits.DL indicates the total throughput of downlink data transmitted at the PDCP layer in a cell.



L.Thrp.Time.DL indicates the duration for transmitting downlink data at the PDCP layer in a cell.

2.2.3 Suggested Measures If both of the following conditions are met: 

Downlink PRB usage ≥ 70%



Downlink user-perceived rate < a user-defined threshold (default value: 2 Mbit/s)

Then: 

If the cell spectral efficiency is low, you are advised to increase the cell throughput by optimizing RF performance.



If the cell spectral efficiency is high, you are advised to: −

Add carriers or expand the bandwidth of the existing carrier.

−

Add eNodeBs.

2.3 Synchronized User Capacity Usage 2.3.1 Monitoring Principles When the number of synchronized users in a cell reaches or exceeds a preconfigured threshold, cell KPIs deteriorate. Connected users include synchronized users and users in the out-of-synchronization state. Synchronized users consume air interface resources and the number of synchronized users is approximately equal to the number of connected users by default. Therefore, the number of connected users (instead of synchronized users) is monitored. NOTE

When the number of connected users in a cell reaches or exceeds the preconfigured threshold, the user-perceived rate has already decreased to an unacceptable level . Therefore, the user-perceived rate should be considered first. The number of connected users in a cell can be considered first when the user capacity of a cell takes priority over user experience.

2.3.2 Monitoring Methods The following item is used in monitoring this case: Synchronized user capacity usage of a cell = L.Traffic.User.Avg/Maximum number of synchronized users in a cell x 100% where 

L.Traffic.User.Avg indicates the average number of connected users in a cell.



The maximum number of synchronized users in a cell is 400 for the LBBPc or 1200 for the LBBPd and UBBP in eRAN7.0.

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2.3.3 Suggested Measures When the synchronized user capacity usage of a local cell reaches or exceeds 60%, you are advised to: 

Reduce the UE inactivity timer length by running the MOD RRCCONNSTATETIMER command with the UeInactiveTimer parameter specified. This measure lifts signaling overhead and increases CPU usage.



If a neighboring cell is lightly loaded, adjust the antenna downtilt angle or decrease the transmit power of the local cell to shrink the coverage area and reduce the number of users in the local cell. In addition, expand the coverage area of the neighboring cell for load balancing.



Add cells or expand the cell bandwidth.



Split the local cell into multiple cells.

2.4 PRACH Resource Usage 2.4.1 Monitoring Principles The PRACH transmits preambles during random access procedures. If the number of contention-based random access attempts in a second reaches or exceeds N , the preamble conflict probability and access delay increase. The values of N are determined during preamble design, considering factors such as that the preamble conflict probability should be less than 1%. If more than 100 non-contention-based random access attempts are initiated per second, dedicated preambles will become insufficient and the eNodeB will instruct the UE to initiate contention-based random access instead, increasing the access delay for the UE. In handover scenarios, the handover procedure is prolonged.


Random preamble usage = (L.RA.GrpA.Att + L.RA.GrpB.Att)/3600/ N x 100%



Dedicated preamble usage = L.RA.Dedicate.Att/3600/100 x 100%

where 

L.RA.GrpA.Att indicates the number of times that random preambles in group A are received.



L.RA.GrpB.Att indicates the number of times that random preambles in group B are received.



L.RA.Dedicate.Att indicates the number of times that dedicated preambles are received.



The value of N varies as follows:

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−

If the system bandwidth is 15 MHz or 20 MHz, N is 100.

−

If the system bandwidth is 5 MHz or 10 MHz and the PRACH resource adjustment algorithm is disabled, N is 50.

−

If the system bandwidth is 5 MHz or 10 MHz and the PRACH resource adjustment algorithm is enabled, N is 100.


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To check whether the PRACH resource adjustment algorithm is enabled, run the LST CELLALGOSWITCH command to query the value of the RachAlgoSwitch.

2.4.3 Suggested Measures You are advised to take the following measures: 

If the random preamble usage reaches or exceeds 75% for X days (three days by default) in a week, enable the adaptive backoff function by running the following command to help reduce the peak RACH load and average access delay: MOD CELLALGOSWITCH: LocalCellId=x, RachAlgoSwitch=BackOffSwitch-1;

If the system bandwidth is 5 MHz or 10 MHz, it is good practice to enable the PRACH resource adjustment algorithm by running the following command: MOD CELLALGOSWITCH: LocalCellId=x,RachAlgoSwitch=RachAdjSwitch-1; 

If the dedicated preamble usage reaches or exceeds 75% for X days (three days by default) in a week, enable the PRACH resource adjustment algorithm and reuse of dedicated preambles between UEs by running the following command: MOD CELLALGOSWITCH: LocalCellId=x,RachAlgoSwitch= RachAdjSwitch-1,RachAlgoSwitch=MaksIdxSwitch-1;

This helps reduce the probability of UEs initiating contention-based random access in the case of dedicated preamble insufficiency and therefore helps reduce the access delay.

2.5 PDCCH Resource Usage 2.5.1 Monitoring Principles This capacity indicator measures the number of control channel elements (CCEs) that can be used by the PDCCH. In each radio frame, CCEs must be allocated to uplink and downlink UEs to be scheduled and common control signaling. PDCCH CCEs must be properly configured and allocated to minimize downlink control overheads as well as to ensure satisfactory user-plane throughput. 

If PDCCH symbols are insufficient, CCEs may fail to be allocated to UEs to be scheduled, which will result in a long service delay and unsatisfactory user experience.



If PDCCH symbols are excessive, which indicates that the usage of PDCCH CCEs is low, the resources that can be used by the P DSCH decreases. This will also result in low spectral efficiency.

2.5.2 Monitoring Methods The following item is used in monitoring this case: CCE usage = (L.ChMeas.CCE.CommUsed + L.ChMeas.CCE.ULUsed + L.ChMeas.CCE.DLUsed)/3600/1000/Max number of PDCCH CCEs x 100% where 

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L.ChMeas.CCE.CommUsed indicates the number of PDCCH CCEs used for common signaling.


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

L.ChMeas.CCE.ULUsed indicates the number of PDCCH CCEs used for uplink scheduling.



L.ChMeas.CCE.DLUsed indicates the number of PDCCH CCEs used for downlink scheduling.



Maximum number of PDCCH CCEs is defined in the following table.

Table 2-2 Maximum number of PDCCH CCEs

System Bandwidth Ng (Configurable)

Maximum Number of PDCCH CCEs Number of PDCCH Symbols = 1

Number PDCCH Symbols = 2

5 MHz

1/6

4

13

21

1/2

4

12

21

1

3

12

20

2

2

11

19

1/6

10

26

43

1/2

9

26

42

1

8

25

41

2

6

23

39

1/6

15

40

65

1/2

14

39

64

1

12

37

62

2

9

34

59

1/6

20

54

87

1/2

19

52

86

1

17

50

84

2

13

46

80

10 MHz

15 MHz

20 MHz

of

Number of PDCCH Symbols = 3

In the preceding table: 



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The number of PDCCH symbols depends on the PDCCH Symbol Number Adjust Switch parameter value, which can be queried by running the LST CELLPDCCHALGO command: −

If the parameter value is On, the number of PDCCH symbols is 3.

−

If the parameter value is Off , the number of PDCCH symbols is equal to the PDCCH Initial Symbol Number parameter value, which can be queried by running the LST CELLPDCCHALGO command.

The value of Ng is equal to the PHICH resource parameter value, which can be queried by running the LST PHICHCFG command. Huawei Proprietary and Confidential Copyright © Huawei Technologies Co., Ltd.

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2.5.3 Suggested Measures 

If the PDCCH Symbol Number Adjust Switch parameter value is Off , you are advised to set this parameter to On by running the following command: MOD CELLPDCCHALGO: LocalCellId=x, PdcchSymNumSwitch=ON;



If the PDCCH Symbol Number Adjust Switch parameter value is set to On and the uplink or downlink PRB usage reaches or exceeds 70%, you are advised to take one of the following measures: −

Add cells or split existing cells.

−

Optimize RF performance to reduce the interference to PDCCH from neighboring cells.

2.6 Connected User License Usage 2.6.1 Monitoring Principles The connected user license specifies the maximum permissible number of users in RRC_CONNECTED mode. If the connected user license usage exceeds a preconfigured threshold, users may fail to access the network.

2.6.2 Monitoring Methods The following item is used in monitoring this case: Connected user license usage = ∑L.Traffic.User.Avg/Licensed number of connected users x 100% where 

L.Traffic.User.Avg indicates the average number of connected users in a cell. ∑L.Traffic.User.Avg indicates the sum of the average number of connected users in all cells under an eNodeB.



The licensed number of connected users can be queried by running the following command: DSP LICENSE: FUNCTIONTYPE=eNodeB;

In the command output, the value of LLT1ACTU01 in the Allocated column is the licensed number of connected users.

2.6.3 Suggested Measures Measures to be taken also depend on the main-control-board CPU usage. If the connected user license usage reaches or exceeds 60% for X days (three days by default) in a week, you are advised to take the following measures: 

If the main-control-board CPU usage is less than 60%, increase the licensed limit.



If the main-control-board CPU usage reaches or exceeds 60%, add an eNodeB.

For details about main-control-board CPU usage, see section 2.9 "Main-Control-Board CPU Usage."

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2.7 Traffic Volume License Usage 2.7.1 Monitoring Principles When the traffic volume of an eNodeB reaches or exceeds the licensed volume, the eNodeB performs flow control, which affects user experience and customer income.

2.7.2 Monitoring Methods The following item is used in monitoring this case: Traffic volume license usage of an eNodeB = ∑(L.Thrp.bits.UL+L.Thrp.bits.DL)/(Licensed eNodeB traffic volume x 3600) x 100% where 

L.Thrp.bits.UL and L.Thrp.bits.DL indicate the uplink traffic volume and downlink traffic volume of a cell, respectively. ∑(L.Thrp.bits.UL+L.Thrp.bits.DL) indicates the sum of uplink and downlink traffic volume of all cells under an eNodeB.



The licensed eNodeB traffic volume can be queried by running the following command: DSP LICENSE: FUNCTIONTYPE=eNodeB;

The licensed eNodeB traffic volume is equal to the Allocated parameter value in the record whose License Identifier is LLT1THRUL01.

2.7.3 Suggested Measures If the traffic volume license usage of an eNodeB reaches or exceeds 80% for X days (three days by default) in a week, you are advised to increase the licensed traffic volume.

2.8 Paging Resource Usage 2.8.1 Monitoring Principles For a 3900 series base station, the maximum number of paging messages that can be sent each second depends on the board configurations as follows: 

LMPT + LBBPc: 1000 messages/second



UMPT + LBBPd or UBBPd: 2400 messages/second

For a BTS3202E or BTS3203E LTE, the maximum number of paging messages that can be sent each second is 500. If the number of paging messages exceeds that capacity, paging messages sent from the eNodeB to UEs may be discarded, which leads to a decrease in the call completion rate.

2.8.2 Monitoring Methods The following items are used in monitoring this case: Percentage of paging messages received over the S1 interface = L.Paging.S1.Rx/3600/Maximum number of paging messages that can be processed per second x 100%

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In the preceding formula, L.Paging.S1.Rx indicates the number of paging messages received over the S1 interface.

2.8.3 Suggested Measures If the percentage of paging messages received by the eNodeB over the S1 interface reaches or exceeds 60% for X days (three days by default) in a week, you are advised to: 

Decrease the number of cells in the tracking area list (TAL) that the congested cell belongs to.



Adjust the paging policy of the core network. That is, reduce the number of paging messages sent after the first or second paging failures to reduce signaling overhead.



Enable the precise paging function if the core network is provided by Huawei.

2.9 Main-Control-Board CPU Usage 2.9.1 Monitoring Principles The CPU usage reflects the busy level of the eNodeB. If the main-control-board CPUs are busy processing control plane or user plane data, signaling-related KPIs may deteriorate, and users may experience a low access success rate, low E-RAB setup success rate, or high service drop rate. Operators can determine whether KPI deterioration is caused by insufficient main-control-board CPU processing capability or poor radio conditions. The evaluation is as follows: 

If the MCS measurement and initial-transmission failure measurement indicate that the channel quality is poor, KPI deterioration may not be caused by main-control-board CPU overload but by deterioration in channel quality.



If the KPIs deteriorate and the main-control-board CPU usage exceeds a preconfigured threshold, you are advised to perform capacity expansion according to section 2.9.3 "Suggested Measures."

2.9.2 Monitoring Methods The following items are used in monitoring this case:  

VS.Board.CPUload.Mean Percentage of times that the main-control-board CPU usage reaches or exceeds a preconfigured threshold (85%) = VS.Board.CPULoad.CumulativeHighloadCount/(3600/5) x 100%

where 

VS.Board.CPUload.Mean indicates the average main-control-board CPU usage.



VS.Board.CPULoad.CumulativeHighloadCount indicates the number of times that the main-control-board CPU usage exceeds a preconfigured threshold.

2.9.3 Suggested Measures The main-control-board CPU of a local eNodeB becomes overloaded if either of the following conditions is met for X days (three days by default) in a week:

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

The average main-control-board CPU usage reaches or exceeds 60%.



The percentage of times that the main-control-board CPU usage reaches or exceeds 85% is greater than or equal to 5%.

Take one of the following measures: 

If a neighboring eNodeB is lightly loaded, adjust the antenna downtilt angles or decrease the transmit power of the local eNodeB to shrink the coverage area and reduce the CPU load of the local eNodeB. In addition, expand the coverage area of the neighboring eNodeB for load balancing.



If the main control board is an LMPT, replace it with a UMPT.



Add eNodeBs.

2.10 Baseband Processing Unit CPU Usage 2.10.1 Monitoring Principles If the eNodeB receives too much traffic volume, which is expressed either in bit/s or packet/s, the baseband processing unit CPU responsible for user plane processing is heavily loaded. As a result, the eNodeB has a low RRC connection setup success rate, low E-RAB setup success rate, low handover success rate, and high service drop rate.

2.10.2 Monitoring Methods The following items are used in monitoring this case:  

VS.Board.CPUload.Mean Percentage of times that the baseband processing unit CPU usage reaches or exceeds a preconfigured threshold (85%) = VS.Board.CPULoad.CumulativeHighloadCount/(3600/5) x 100%

where 

VS.Board.CPUload.Mean indicates the average baseband processing unit CPU usage.



VS.Board.CPULoad.CumulativeHighloadCount indicates the number of times that the baseband processing unit CPU usage exceeds a preconfigured threshold.

2.10.3 Suggested Measures The baseband processing unit CPU becomes overloaded if either of the following conditions is met for X days (three days by default) in a week: 

The average baseband processing unit CPU usage reaches or exceeds 60%.



The percentage of times that the baseband processing unit CPU usage reaches or exceeds 85% is greater than or equal to 5%.

When the baseband processing unit CPU is overloaded, you are advised to perform capacity expansion on the eNodeB user plane as follows: 

If the baseband processing unit is an LBBPc, replace the LBBPc with an LBBPd.



Add a baseband processing unit to share the network load, and then determine whether to move existing cells or add new cells based on the number of UEs. The capacity expansion methods are as follows:

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eRAN7.0 Capacity Monitoring Guide −

−




If the radio resources are sufficient (that is, the usage of each type of radio resources is lower than the threshold), move cells from the existing baseband processing unit to the new baseband processing unit. If the radio resources are insufficient, set up new cells on the new baseband processing unit.

If the eNodeB has multiple baseband processing units and one of them is overloaded, move cells from the overloaded baseband processing unit to a baseband processing unit with a lighter load. Baseband processing unit load can be indicated by the following: −

Average CPU usage

−

Percentage of times that the CPU usage reaches or exceeds a preconfigured threshold

− 

Number of cells established on a baseband processing unit

If the eNodeB already has a maximum of six baseband processing units and more baseband processing units are required, add an eNodeB.

2.11 Transport Resource Group Usage 2.11.1 Monitoring Principles A transport resource group carries a set of data streams, which can be local data or forwarded data. Local data is classified into control plane, user plane, operation and maintenance (OM), and IP clock data. Forwarded data is not divided into different types. If a transport resource group is congested, it cannot transmit or forward data, which affects service provision. A transport resource group for user plane data is a monitored object. Figure 2-1 shows the position of transport resource group in the TCP/IP model. Figure 2-1 The position of the transport resource group

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Proportion of the average transmission rate to the configured bandwidth = VS.RscGroup.TxMeanSpeed/Bandwidth configured for the transport resource group x 100%



Proportion of the maximum transmission rate to the configured bandwidth = VS.RscGroup.TxMaxSpeed/Bandwidth configured for the transport resource group x 100%

where 

VS.RscGroup.TxMeanSpeed indicates the average transmission rate of a transport resource group.



VS.RscGroup.TxMaxSpeed indicates the maximum transmission rate of a transport resource group.



The bandwidth configured for a transport resource group can be queried by running the following command: DSP RSCGRP: CN=x, SRN=x, SN=x, BEAR=xx, SBT=xxxx, PT=xxx;

In the command output, the value of Tx Bandwidth is the bandwidth configured for the transport resource group.

2.11.3 Suggested Measures A transport resource group is congested if one of the following conditions is met: 

The proportion of the average transmission rate to the configured bandwidth reaches or exceeds 80% for five days in a week.



The proportion of the maximum transmission rate to the configured bandwidth reaches or exceeds 90% for two days in a week.

When a transport resource group is congested, you are advised to expand the bandwidth of the transport resource group. The following is an example command: MOD RSCGRP: CN=x, SRN=x, SN=x, BEAR=IP, SBT=BASE_BOARD, PT=ETH, PN=x, RSCGRPID=x, RU=x, TXBW=xxxx, RXBW=xxxx;

If the problem persists after the bandwidth adjustment, you are advised to expand the eNodeB bandwidth.

2.12 Ethernet Port Traffic 2.12.1 Monitoring Principles The Ethernet port traffic is the channel traffic at the physical layer, including uplink and downlink traffic. The eNodeB Ethernet port traffic reflects the throughput and communication quality of the Ethernet ports on the main control board of the eNodeB. Based on the monitoring results, you can determine whether the transmission capacity allocated by an operator for the S1 and X2 interfaces on the eNodeB meet the requirements for uplink and downlink transmissions.

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(Item 1) Proportion of the average uplink transmission rate to the allocated bandwidth = VS.FEGE.TxMeanSpeed/Allocated bandwidth x 100%



(Item 2) Proportion of the maximum uplink transmission rate to the allocated bandwidth = VS.FEGE.TxMaxSpeed/Allocated bandwidth x 100%



(Item 3) Proportion of the average downlink reception rate to the allocated bandwidth = VS.FEGE.RxMeanSpeed/Allocated bandwidth x 100%



(Item 4) Proportion of the maximum downlink reception rate to the allocated bandwidth = VS.FEGE.RxMaxSpeed/Allocated bandwidth x 100%

where 

VS.FEGE.TxMeanSpeed indicates the average transmission rate of an Ethernet port.



VS.FEGE.TxMaxSpeed indicates the maximum transmission rate of an Ethernet port.



VS.FEGE.RxMeanSpeed indicates the average reception rate of an Ethernet port.



VS.FEGE.RxMaxSpeed indicates the maximum reception rate of an Ethernet port.



The allocated bandwidth can be queried by referring to Table 2-3.

Table 2-3 Allocated bandwidth

Value of LR Switch

Main Control Board

Allocated Bandwidth

Disable

UMPT

1 Gbit/s

LMPT

BTS3202E board BTS3203E LTE board Enable

UMPT LMPT

or



For items 1 and 2: 360 Mbit/s












For items 1 and 2: value of UL Committed Information Rate (Kbit/s)



For items 3 and 4: value of DL Committed Information Rate (Kbit/s)



You can run the LST LR command to query the values of LR Switch, UL Committed Information Rate (Kbit/s), and DL Committed Information Rate (Kbit/s) .



The types of main control boards can be queried by running the following command: DSP BRD: CN=x, SRN=x, SN=x;

In the command output, the value of Config Type is the type of the main control board.

2.12.3 Suggested Measures You are advised to perform transmission capacity expansion if either of the following conditions is met:

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

The proportion of the average uplink transmission rate (or downlink reception rate) to the allocated bandwidth reaches or exceeds 70% for at least five days in a week. The allocated bandwidth is 750 Mbit/s by default. The actually allocated bandwidth can be obtained from the operator.



The proportion of the maximum uplink transmission rate (or downlink reception rate) to the allocated bandwidth reaches or exceeds 85% for at least two days in a week.

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3

3 Resource Allocation Problem Identification

Resource Allocation Problem Identification

This chapter describes how to identify resource allocation problems. Network abnormalities can be found through KPI monitoring. If a KPI is deteriorated, users can analyze the access counters (RRC resource congestion rate and E-RAB resource congestion rate) to check whether the deterioration is caused by resource congestion.

3.1 Resource Congestion Indicators Resource congestion indicators (such as the RRC resource congestion rate and E-RAB resource congestion rate) can be used to check whether the network is congested. Table 3-1 lists the counters related to KPIs. Table 3-1 Counters related to KPIs Performance Counter

Description

L.RRC.ConnReq.Att

Number of RRC Connection Request messages received from UEs in a cell (excluding retransmitted messages)

L.RRC.ConnReq.Succ

Number of RRC Connection Setup Complete messages received from UEs in a cell

L.E-RAB.AttEst

Number of E-UTRAN radio access bearer (E-RAB) setup attempts initiated by UEs in a cell

L.E-RAB.SuccEst

Number of successful E-RAB setups initiated by UEs in a cell

L.E-RAB.AbnormRel

Number of times that the eNodeB abnormally releases E-RABs that are transmitting data in a cell

L.E-RAB.NormRel

Number of times that the eNodeB normally releases E-RABs in a cell

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3.1.1 RRC Resource Congestion Rate The RRC resource congestion rate is a cell-level indicator. It is calculated using the following formula: RRC resource congestion rate = L.RRC.SetupFail.ResFail/L.RRC.ConnReq.Att x 100% where 

L.RRC.SetupFail.ResFail indicates the number of RRC connection setup failures due to resource allocation failures.



L.RRC.ConnReq.Att indicates the number of RRC connection setup requests.

If the RRC resource congestion rate is higher than 0.2%, KPI deterioration is caused by resource congestion.

3.1.2 E-RAB Resource Congestion Rate The E-RAB resource congestion rate is a cell-level indicator. It is calculated using the following formula: E-RAB resource congestion rate = L.E-RAB.FailEst.NoRadioRes/L.E-RAB.AttEst x 100% where 

L.E-RAB.FailEst.NoRadioRes indicates the number of E-RAB setup failures due to radio resource insufficiency.



L.E-RAB.AttEst indicates the number of E-RAB setup attempts.

If the E-RAB resource congestion rate is higher than 0.2%, KPI deterioration is caused by resource congestion.

3.2 Resource Allocation Problem Identification Process Figure 3-1 shows the Resource Allocation Problem Identification Process.

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Figure 3-1 Resource allocation problem identification process

The fault location procedure begins with the identification of abnormal KPIs, followed up by selecting and performing a KPI analysis on the top N cells. Cell congestion mainly results from insufficient system resources. Bottlenecks can be detected by analyzing the access counters (RRC resource congestion rate and E-RAB resource congestion rate).

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4 Related Counters

4

Related Counters

Table 4-1 lists counters involved in capacity monitoring. Table 4-1 Counters involved in capacity monitoring.

Resource Type

Counter Name

Description

PRBs

L.ChMeas.PRB.DL.Used.Avg

Average number of used downlink PRBs

L.ChMeas.PRB.DL.Avail

Number of available downlink PRBs

L.Thrp.bits.DL

Total downlink traffic volume for PDCP SDUs in a cell

L.Thrp.Time.DL

Total transmit duration of downlink PDCP SDUs in a cell

L.RA.GrpA.Att

Number of times the contention preamble in group A is received

L.RA.GrpB.Att

Number of times the contention preamble in group B is received

L.RA.Dedicate.Att

Number of times the non-contention-based preamble is received

L.ChMeas.CCE.CommUsed

Number of PDCCH CCEs used for common DCI

L.ChMeas.CCE.ULUsed

Number of PDCCH CCEs used for uplink DCI

L.ChMeas.CCE.DLUsed

Number of PDCCH CCEs used for downlink DCI

L.ChMeas.CCE.Avail

Number of available CCEs

Connected user

L.Traffic.User.Avg

Average number of users in a cell

Paging resources

L.Paging.S1.Rx

Number of received paging messages over the S1 interface in a cell

PRACH resources

PDCCH resources

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Capacity Monitoring Guide

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