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eRAN7.0
Capacity Monitoring Guide
Issue DraftA
Date 2014-1-20
HUAWEI TECHNOLOGIES CO., LTD.
Issue DraftA (2014-1-20) 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 or transmitted in any form or by any 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]
eRAN7.0 Capacity Monitoring Guide About This Document
Issue DraftA (2014-1-20) Huawei Proprietary and Confidential
Copyright Huawei Technologies Co., Ltd.
ii
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 affects network QoS and user experience.
NOTE
For definitions of the man-machine language (MML) commands, parameters, alarms, and
performance counters mentioned in this document, see the "Operation and Maintenance" part in
3900 Series LTE eNodeB Product Documentation for eNodeB base station, BTS3202E Product
Documentation for BTS3202E base station, and BTS3203E LTE Product Documentation for
BTS3203E base 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 Product Version
DBS3900 V100R009C00
The mapping single-mode base station version is:
eNodeB: V100R007C00 BTS3900
BTS3900A
BTS3900L
BTS3900AL
BTS3202E
BTS3203E
eRAN7.0 Capacity Monitoring Guide About This Document
Issue DraftA (2014-1-20) Huawei Proprietary and Confidential
Copyright Huawei Technologies Co., Ltd.
iii
Intended Audience
This document is intended for:
Field engineers
Network planning engineers
Change History
This section describes changes in each issue of this document.
Draft A (2014-1-20)
Draft A (2014-1-20)
This is the first draft.
eRAN7.0 Capacity Monitoring Guide Contents
Issue DraftA (2014-1-20) Huawei Proprietary and Confidential
Copyright Huawei Technologies Co., Ltd.
iv
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 ............................................................................................................................... 5
2.2.1 Monitoring Principles ............................................................................................................................. 5
2.2.2 Monitoring Methods ............................................................................................................................... 6
2.2.3 Suggested Measures ................................................................................................................................ 6
2.3 PRACH Resource Usage .................................................................................................................................. 6
2.3.1 Monitoring Principles ............................................................................................................................. 6
2.3.2 Monitoring Methods ............................................................................................................................... 6
2.3.3 Suggested Measures ................................................................................................................................ 7
2.4 PDCCH Resource Usage .................................................................................................................................. 7
2.4.1 Monitoring Principles ............................................................................................................................. 7
2.4.2 Monitoring Methods ............................................................................................................................... 8
2.4.3 Suggested Measures ................................................................................................................................ 8
2.5 Connected User License Usage ........................................................................................................................ 8
2.5.1 Monitoring Principles ............................................................................................................................. 8
2.5.2 Monitoring Methods ............................................................................................................................... 8
2.5.3 Suggested Measures ................................................................................................................................ 9
2.6 Paging Resource Usage .................................................................................................................................... 9
2.6.1 Monitoring Principles ............................................................................................................................. 9
2.6.2 Monitoring Methods ............................................................................................................................... 9
2.6.3 Suggested Measures ................................................................................................................................ 9
2.7 Main-Control-Board CPU Usage ................................................................................................................... 10
2.7.1 Monitoring Principles ........................................................................................................................... 10
2.7.2 Monitoring Methods ............................................................................................................................. 10
2.7.3 Suggested Measures .............................................................................................................................. 10
2.8 LBBP CPU Usage .......................................................................................................................................... 11
2.8.1 Monitoring Principles ........................................................................................................................... 11
eRAN7.0 Capacity Monitoring Guide Contents
Issue DraftA (2014-1-20) Huawei Proprietary and Confidential
Copyright Huawei Technologies Co., Ltd.
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2.8.2 Monitoring Methods ............................................................................................................................. 11
2.8.3 Suggested Measures .............................................................................................................................. 11
2.9 Transport Resource Group Usage ................................................................................................................... 12
2.9.1 Monitoring Principles ........................................................................................................................... 12
2.9.2 Monitoring Methods ............................................................................................................................. 12
2.9.3 Suggested Measures .............................................................................................................................. 13
2.10 Ethernet Port Traffic ..................................................................................................................................... 13
2.10.1 Monitoring Principles ......................................................................................................................... 13
2.10.2 Monitoring Methods ........................................................................................................................... 13
2.10.3 Suggested Measures ............................................................................................................................ 14
3 Resource Allocation Problem Identification ......................................................................... 15
3.1 Resource Congestion Indicators ..................................................................................................................... 15
3.1.1 RRC Resource Congestion Rate ........................................................................................................... 16
3.1.2 E-RAB Resource Congestion Rate ....................................................................................................... 16
3.2 Resource Allocation Problem Identification Process ..................................................................................... 16
4 Related Counters ......................................................................................................................... 18
eRAN7.0 Capacity Monitoring Guide 1 Overview
Issue DraftA (2014-1-20) Huawei Proprietary and Confidential
Copyright Huawei Technologies Co., Ltd.
1
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.
eRAN7.0 Capacity Monitoring Guide 1 Overview
Issue DraftA (2014-1-20) Huawei Proprietary and Confidential
Copyright Huawei Technologies Co., Ltd.
2
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
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
eNodeB
resources
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
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
LTE baseband
process unit (LBBP)
CPU
Processing capability of
the LBBP board
KPIs deteriorate. LBBP CPU Usage
Transport resource
groups
eNodeB logical
transport resources
Packets may be
lost, affecting
user experience.
Transport Resource
Group Usage
Ethernet ports eNodeB physical
transport resources
Packets may be
lost, affecting
user experience.
Ethernet Port Traffic
eRAN7.0 Capacity Monitoring Guide 1 Overview
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Copyright Huawei Technologies Co., Ltd.
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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 experiences. For example, the 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 can define thresholds based on the actual situation.
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.
eRAN7.0 Capacity Monitoring Guide 2 Capacity Monitoring
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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
Cell
resources
Downlink User
Perception
Downlink PRB usage 70% and downlink user-perceived rate < 2
Mbit/s (default value,
user-configurable)
Add carriers or
eNodeBs.
PRACH Resource Usage Usage of preambles for
contention-based access 75% Enable the adaptive
Backoff or resource
adjustment algorithm for
the PRACH.
Usage of preambles for
non-contention-based access 75% Enable the PRACH
resource adjustment
algorithm and reuse of
dedicated preambles
between UEs.
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Resource Type
Monitoring Item Conditions Handling Suggestions
PDCCH Resource Usage CCE usage 80%
Uplink or downlink
PRB usage < 90%
Set PDCCH Symbol
Number Adjust Switch to On.
Uplink or downlink
PRB usage 90% No handling is required.
eNodeB
resources
Connected User License
Usage
Connected
user license
usage 60%
Main-control-board
CPU usage < 60% Add licenses.
Main-control-board
CPU usage 60% Add eNodeBs.
Paging Resource Usage
Percentage of paging messages
received on the S1 interface 60% or number of paging messages 1500
Decrease the number of
cells in the tracking area
list (TAL) that the
congested cell belongs
to.
Main-Control-Board
CPU Usage
Average main-control-board CPU
usage 60% or percentage of times that the CPU usage reaches or
exceeds 85% 5%
Expand the control-plane
capacity of the eNodeB.
LBBP CPU Usage Average LBBP CPU usage 60% or percentage of times that the CPU
usage reaches or exceeds 85% 5%
Expand the user-plane
capacity of the eNodeB.
Transport Resource
Group Usage
Packet loss rate 0.05%, proportion of average transmission rate to
configured bandwidth 80%, or proportion of maximum transmission
rate to configured bandwidth 90%
Expand the bandwidth of
the transport resource
group.
Ethernet Port Traffic Proportion of average transmission
rate to allocated bandwidth 70% or Proportion of maximum transmission
rate to allocated bandwidth 85%
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. The
monitoring principles also apply to uplink.
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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
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
Add carriers or eNodeBs 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)
2.3 PRACH Resource Usage
2.3.1 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.
2.3.2 Monitoring Methods
The following items are used in monitoring this case:
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.
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The value of N varies as follows:
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.
To check whether the PRACH resource adjustment algorithm is enabled, run the LST
CELLALGOSWITCH command to query the value of the RachAlgoSwitch.
2.3.3 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.
2.4 PDCCH Resource Usage
2.4.1 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 PDSCH decreases. This will also result in low
spectral efficiency.
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If the value of PDCCH Symbol Number Adjust Switch is On, you do not need to monitor PDCCH
resource usage. The reason is that the eNodeB automatically adjusts the number of PDCCH symbols
based on the CCE load to meet the CCE requirement while preventing excessive PDSCH resource
consumption. You can run the LST CELLPDCCHALGO command to query the setting of PDCCH
Symbol Number Adjust Switch.
2.4.2 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)/L.ChMeas.CCE.Avail x 100%
where
L.ChMeas.CCE.CommUsed indicates the number of PDCCH CCEs used for common
signaling.
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.
L.ChMeas.CCE.Avail indicates the number of available CCEs.
2.4.3 Suggested Measures
Measures to be taken also depend on the PRB usage.
If the CCE usage reaches or exceeds 80% and the uplink or downlink PRB usage is less than
90% for X days (three days by default) in a week:
If the value of PDCCH Symbol Number Adjust Switch is Off, turn on the switch by
running the following command:
MOD CELLPDCCHALGO: LocalCellId=x, PdcchSymNumSwitch=ON;
If the uplink or downlink PRB usage reaches or exceeds 90%, no handling is required.
For details about uplink or downlink PRB usage, see section 2.2 "Downlink User Perception".
2.5 Connected User License Usage
2.5.1 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.
2.5.2 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
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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.
2.5.3 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 2.7 "Main-Control-Board CPU
Usage."
2.6 Paging Resource Usage
2.6.1 Monitoring Principles
The eNodeB and BTS3202E or BTS3203E LTE can process a maximum of 750 and 500
paging messages per second, respectively. 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.
2.6.2 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%
L.Paging.Dis.Num
where
L.Paging.S1.Rx indicates the number of paging messages received over the S1 interface.
L.Paging.Dis.Num indicates the number of paging messages discarded over the Uu
interface.
2.6.3 Suggested Measures
You are advised to decrease the number of cells in the tracking area list (TAL) that the
congested cell belongs to if either of the following conditions is met for X days (three days by default) in a week:
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The percentage of paging messages received by the eNodeB over the S1 interface
reaches or exceeds 60%.
1500 or more paging messages from the mobility management entity (MME) to UEs are
discarded in a day.
2.7 Main-Control-Board CPU Usage
2.7.1 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 2.7.3
"Suggested Measures."
2.7.2 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 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.
2.7.3 Suggested Measures
The main-control-board CPU becomes overloaded if either of the following conditions is met
for X days (three days by default) in a week:
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%.
When the main-control-board CPU is overloaded, you are advised to add an eNodeB and
connect it to the evolved packet core (EPC) through a new S1 interface.
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2.8 LBBP CPU Usage
2.8.1 Monitoring Principles
If the eNodeB receives too much traffic volume, which is expressed either in bit/s or packet/s,
the LBBP 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.
2.8.2 Monitoring Methods
The following items are used in monitoring this case:
VS.Board.CPUload.Mean
Percentage of times that the LBBP CPU usage reaches or exceeds a preconfigured
threshold (85%) = VS.Board.CPULoad.CumulativeHighloadCount/3600 x 100%
where
VS.Board.CPUload.Mean indicates the average LBBP CPU usage.
VS.Board.CPULoad.CumulativeHighloadCount indicates the number of times that the
LBBP CPU usage exceeds a preconfigured threshold.
2.8.3 Suggested Measures
The LBBP CPU becomes overloaded if either of the following conditions is met for X days (three days by default) in a week:
The average LBBP CPU usage reaches or exceeds 60%.
The percentage of times that the LBBP CPU usage reaches or exceeds 85% is greater
than or equal to 5%.
When the LBBP CPU is overloaded, you are advised to perform capacity expansion on the
eNodeB user plane as follows:
If the LBBP is an LBBPc, replace the LBBPc with an LBBPd.
Add an LBBP 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:
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 LBBP to the new LBBP.
If the radio resources are insufficient, set up new cells on the new LBBP.
If the eNodeB has multiple LBBPs and one of them is overloaded, move cells from the
overloaded LBBP to an LBBP with a lighter load.
LBBP 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 an LBBP
If the eNodeB already has a maximum of six LBBPs and more LBBPs are required, add
an eNodeB.
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2.9 Transport Resource Group Usage
2.9.1 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
2.9.2 Monitoring Methods
The following items are used in monitoring this case:
Packet loss rate = VS.RscGroup.TxDropPkts/VS.RscGroup.TxPkts x100%
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.TxDropPkts indicates the number of packets discarded because of
transmission failures of a transport resource group.
VS.RscGroup.TxPkts indicates the number of packets transmitted by a transport resource
group.
VS.RscGroup.TxMeanSpeed indicates the average transmission rate of a transport
resource group.
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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.
2.9.3 Suggested Measures
A transport resource group is congested if one of the following conditions is met:
The packet loss rate reaches or exceeds 0.05% for five days in a week
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.
2.10 Ethernet Port Traffic
2.10.1 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.
2.10.2 Monitoring Methods
The following items are used in monitoring this case:
(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
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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 2-2.
Table 2-2 Allocated bandwidth
Value of LR Switch
Main Control Board Allocated Bandwidth
Disable UMPT 1 Gbit/s
LMPT For items 1 and 2: 360 Mbit/s
For items 3 and 4: 540 Mbit/s
BTS3202E board or
BTS3203E LTE board
For items 1 and 2: 60 Mbit/s
For items 3 and 4: 178 Mbit/s
Enable UMPT 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) LMPT
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.
2.10.3 Suggested Measures
You are advised to perform transmission capacity expansion if either of the following
conditions is met:
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 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 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
PRACH
resources
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
PDCCH
resources
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
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Resource Type
Counter Name Description
L.Paging.Dis.Num Number of discarded paging messages
from the MME to UEs due to flow
control in a cell
Board CPU
resources
VS.Board.CPUload.Mean Average Board CPU Usage
VS.Board.CPULoad.Cumulative
HighloadCount
Number of Times that the CPU Usage of
Boards Exceeds the Preconfigured
Threshold
Transport
resource
groups
VS.RscGroup.TxPkts Number of packets successfully
transmitted by the resource group
VS.RscGroup.TxDropPkts Number of packets discarded by the
resource group due to transmission
failures
VS.RscGroup.TxMaxSpeed Maximum transmit rate of the resource
group
VS.RscGroup.TxMeanSpeed Average transmit rate of the resource
group
Ethernet ports VS.FEGE.TxMaxSpeed Maximum transmit rate on the Ethernet
port
VS.FEGE.TxMeanSpeed Average transmit rate on the Ethernet
port
VS.FEGE.RxMaxSpeed Maximum receive rate on the Ethernet
port
VS.FEGE.RxMeanSpeed Average receive rate on the Ethernet port
About This DocumentDraft A (2014-1-20)
1 Overview1.1 Network ResourcesTable 1-1 Network resources
1.2 Capacity Monitoring Methods
2 Capacity Monitoring2.1 IntroductionTable 2-1 Types of resources to be monitored, thresholds, and handling suggestions
2.2 Downlink User Perception2.2.1 Monitoring Principles2.2.2 Monitoring Methods2.2.3 Suggested Measures
2.3 PRACH Resource Usage2.3.1 Monitoring Principles2.3.2 Monitoring Methods2.3.3 Suggested Measures
2.4 PDCCH Resource Usage2.4.1 Monitoring Principles2.4.2 Monitoring Methods2.4.3 Suggested Measures
2.5 Connected User License Usage2.5.1 Monitoring Principles2.5.2 Monitoring Methods2.5.3 Suggested Measures
2.6 Paging Resource Usage2.6.1 Monitoring Principles2.6.2 Monitoring Methods2.6.3 Suggested Measures
2.7 Main-Control-Board CPU Usage2.7.1 Monitoring Principles2.7.2 Monitoring Methods2.7.3 Suggested Measures
2.8 LBBP CPU Usage2.8.1 Monitoring Principles2.8.2 Monitoring Methods2.8.3 Suggested Measures
2.9 Transport Resource Group Usage2.9.1 Monitoring PrinciplesFigure 2-1 The position of the transport resource group
2.9.2 Monitoring Methods2.9.3 Suggested Measures
2.10 Ethernet Port Traffic2.10.1 Monitoring Principles2.10.2 Monitoring Methods2.10.3 Suggested Measures
3 Resource Allocation Problem Identification3.1 Resource Congestion Indicators3.1.1 RRC Resource Congestion Rate3.1.2 E-RAB Resource Congestion Rate
3.2 Resource Allocation Problem Identification Process
4 Related Counters