AQM (eRAN3.0 - 04)

AQM
eRAN3.0
Feature Parameter Description
Issue 04
Date 2013-05-20
HUAWEI TECHNOLOGIES CO., LTD.

Copyright © Huawei Technologies Co., Ltd. 2013. 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 the 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: support@huawei.com
eRAN
AQM Contents
Contents
1 Introduction ................................................................................................................................1-1
1.1 Scope ............................................................................................................................................ 1-1
1.2 Intended Audience......................................................................................................................... 1-1
1.3 Change History.............................................................................................................................. 1-1
2 Overview of AQM ......................................................................................................................2-1

3 Technical Description ..............................................................................................................3-1
4 Related Features .......................................................................................................................4-1
4.1 Required Features......................................................................................................................... 4-1
4.2 Mutually Exclusive Features ......................................................................................................... 4-1
4.3 Affected Features .......................................................................................................................... 4-1
5 Impact on the Network.............................................................................................................5-1

5.1 Impact on System Capacity........................................................................................................... 5-1
5.2 Impact on Network Performance................................................................................................... 5-1
6 Engineering Guidelines ...........................................................................................................6-1

6.1 When to Use AQM......................................................................................................................... 6-1
6.2 Information to Be Collected ........................................................................................................... 6-1
6.3 Network Planning .......................................................................................................................... 6-1
6.4 Deploying AQM ............................................................................................................................. 6-1
6.4.1 Deployment Requirements ................................................................................................... 6-1
6.4.2 Data Preparation................................................................................................................... 6-2
6.4.3 Initial Configuration ............................................................................................................... 6-2
6.4.4 Commissioning ..................................................................................................................... 6-3
6.4.5 Activation Observation .......................................................................................................... 6-3
6.4.6 Reconfiguration .................................................................................................................... 6-4
6.4.7 Deactivation .......................................................................................................................... 6-4
6.5 Performance Optimization ............................................................................................................. 6-4
6.6 Troubleshooting ............................................................................................................................. 6-4
6.6.1 Fault Description ................................................................................................................... 6-4
6.6.2 Fault Handling ...................................................................................................................... 6-4
7 Parameters..................................................................................................................................7-1
8 Counters ......................................................................................................................................8-1
9 Glossary ......................................................................................................................................9-1
10 Reference Documents .........................................................................................................10-1
Issue 04 (2013-05-20) Huawei Proprietary and Confidential i

Copyright © Huawei Technologies Co., Ltd.
eRAN
AQM 1 Introduction
1 Introduction
1.1 Scope
This document describes the active queue management (AQM) feature of E-UTRAN NodeBs (eNodeBs)
in terms of key techniques and engineering guidelines.
Any managed objects (MOs), parameters, alarms, or counters described in this document correspond to
the software release delivered with this document. In the event of updates, the updates will be described
in the product documentation delivered with the latest software release.
1.2 Intended Audience

This document is intended for:
 Personnel who need to understand AQM
 Personnel who work with Huawei Long Term Evolution (LTE) products
1.3 Change History

This section provides information about the changes in different document versions.
There are two types of changes, which are defined as follows:
 Feature change: refers to a change in the AQM feature of a specific product version.
 Editorial change: refers to a change in wording or the addition of information that was not described in
the earlier version.
Document Issues
The document issues are as follows:
 04 (2013-05-20)
 03 (2013-02-27)
 02 (2012-05-11)
 01 (2012-03-30)
 Draft A (2012-01-10)
04 (2013-05-20)
Compared with issue 03 (2013-02-27) of eRAN3.0, issue 04 (2013-05-20) of eRAN3.0 includes the
following changes.
Change Type Change Description Parameter Change

Feature change None None
Editorial change Revised chapter 5.1 “Impact on System Capacity”. None
03 (2013-02-27)
following changes.
Issue 04 (2013-05-20) Huawei Proprietary and Confidential 1-1

eRAN
AQM 1 Introduction

Editorial change Revised chapter 6 "Engineering Guidelines." Deleted descriptions about
service differentiation.
02 (2012-05-11)
following changes.

Editorial change Revised chapter 6 "Engineering Guidelines." None
01 (2012-03-30)
This is the first official release.
Compared with draft A (2012-01-10) of eRAN3.0, issue 01 (2012-03-30) of eRAN3.0 includes the
following changes.

Editorial change Revised chapter 6 "Engineering Guidelines." None
Draft A (2012-01-10)
This is a draft.
Compared with issue 01 (2011-09-30) of eRAN2.2, draft A (2012-01-10) of eRAN3.0 includes the
following changes.

Editorial change Added chapters 4 "Related Features" and 5 "Impact None
on the Network."

eRAN
AQM 2 Overview of AQM
2 Overview of AQM
A radio link has a lower bandwidth than a wired link. In addition, the bandwidth of a radio link fluctuates.
Therefore, a large amount of buffered data may congest the air interface during downlink data
transmission.
AQM is introduced to actively discard packets, while maintaining a high level of link usage. AQM relieves
queue congestion and reduces the transmission delay of the services (for example, web browsing) that
have a high requirement for interaction. This feature provides an improved user experience.
AQM has the following benefits:
 Detects possible congestion in the buffer queue at the earliest time and minimizes the probability of
congestion by discarding packets
 Maintains a relatively short queue to reach a tradeoff between the data throughput and transmission
delay
 Avoids global synchronization caused by simultaneous overflow of multiple data streams
 Packet arrival at a buffer queue usually bursts because of data burst. Therefore, when the queue is full or nearly full, a
large number of data packets are lost. Upon detection of lost packets, multiple Transmission Control Protocol (TCP)
senders sharply decrease the send window by reducing the transmit (TX) data amount. Then, the packet arrival rate
declines quickly. In this way, the network is not congested. The TCP senders start to increase the transmission rate
after detecting that the network is not congested, which again results in network congestion. This problem occurs
repeatedly. The repeated occurrences are called global synchronization.
 Currently, AQM applies only to IPv4 type user-plane packets, not IPv6 type user-plane packets.
Huawei AQM applies to non-GBR (GBR is short for guaranteed bit rate) services.
This document describes optional feature LOFD-001027 Active Queue Management (AQM). AQM is
controlled by the CellAlgoSwitch.AqmAlgoSwitch parameter.

eRAN
AQM 3 Technical Description
3 Technical Description
If AQM detects that the number of packets in a buffer queue (that is, the queue length) exceeds a
specified threshold, it discards TCP packets selectively based on ports to avoid possible congestion. In
this way, AQM reduces the delay of interactive services and improves fairness among data streams.
The working area of AQM is divided into normal, congestion avoidance, and congestion control areas
based on the minimum and maximum congestion thresholds. Figure 3-1 shows the AQM working area,
where Max represents the maximum packet discard rate of a non-GBR service in the congestion
avoidance area. In this figure, the red lines denote the packet discard rate.
Figure 3-1 AQM working area
AQM calculates the average queue length and compares it with the minimum and maximum congestion
thresholds. AQM then performs different operations under each of the following conditions:
 Average queue length ≤ Minimum congestion threshold
In the normal area, AQM does not discard any packet because the queue is not congested.
 Minimum congestion threshold < Average queue length < Maximum congestion threshold
In the congestion avoidance area, AQM discards some packets because the queue is congested to
some extent. The probability of discarding packets increases linearly with the average queue length
and the amount of data in the stream sent successfully to the eNodeB.
 Average queue length ≥ Maximum congestion threshold
In the congestion control area, AQM discards every newly arriving packet because the queue is
severely congested.

eRAN
AQM 4 Related Features
4 Related Features
This chapter describes the eNodeB features related to AQM, including required features, mutually
exclusive features, and affected features.
4.1 Required Features

None
4.2 Mutually Exclusive Features

None
4.3 Affected Features

LOFD-001026 TCP Proxy Enhancer (TPE)
If AQM detects that the eNodeB is congested (that is, packets are discarded), AQM informs TCP Proxy
Enhancer (TPE), to request TPE to stop acknowledgment (ACK) splitting.

eRAN
AQM 5 Impact on the Network
5 Impact on the Network

This chapter describes the impact of AQM on the network in terms of system capacity and network
performance.
5.1 Impact on System Capacity

When AQM is enabled, the processing delay of downlink packets carried by non-GBR bearers
decreases. Therefore, the delay of delay-sensitive services, such as HTTP services and small file
downloads, decreases. The processing delay can be monitored by dividing the value of the
L.Traffic.DL.PktDelay.Time.QCI.x counter by the value of the L.Traffic.DL.PktDelay.Num.QCI.x counter.
However, when AQM is enabled, the cell throughput decreases, some UEs' throughput fluctuates, or the
throughput for non-GBR services decreases. If GRB and non-GBR services coexist in a cell, and the
actual GBR service rate is smaller than the subscribed GBR service rate, the scheduling opportunities
for GBR services increase because the throughput for non-GBR services decreases. Therefore, the
throughput for GRB services increases.
5.2 Impact on Network Performance

The network key performance indicators (KPIs) related to the system throughput fluctuate.

eRAN
AQM 6 Engineering Guidelines
6 Engineering Guidelines
This chapter provides engineering guidelines for AQM.
6.1 When to Use AQM

AQM is used for queue management of user plane data in LTE networks.
AQM applies to downlink hybrid-service scenarios where multiple TCP services are running on one
bearer. In such scenarios, the TCP services with a larger traffic volume occupy air interface resources for
a long time. The air interface resources for the TCP services with a smaller traffic volume are insufficient,
and a large amount of data is buffered in the eNodeB. As a result, the latency of services that require a
quick response (real-time services such as web browsing or small-file download) is prolonged, and user
experience deteriorates sharply.
Huawei AQM applies only to non-GBR services and TCP services.
Enable AQM in the following scenarios:
 The congestion probability and packet loss rate in specific cells are abnormally high, user experience
with interactive services deteriorates, and you have determined that the problem occurs due to a large
amount of downlink data. If the problem is not caused by a large amount of downlink data, enabling
AQM may cause further deterioration of the service quality.
 Multiple TCP-based bit torrent (BT) services are running or large files are being downloaded while lots
of interactive services are running on the network.
In the following scenarios, AQM brings no gain or could even have slightly negative effects:
 There are both TCP and User Datagram Protocol (UDP) services on a bearer.
Discarding TCP and UDP packets in this scenario can reduce the TCP traffic but not the UDP traffic.
 Packets are randomly discarded by AQM during network congestion. If packets of interactive services
are discarded, user experience with these services deteriorates.
 The data rate of cell edge users (CEUs) fluctuates due to interference. In this scenario, the eNodeB is
not congested and AQM brings little gain.
 Discarding packets can cause throughput fluctuations, especially when there are only a small number
(for example, one or two) of TCP connections.
 The downlink throughput on a bearer exceeds 30 Mbit/s. In this scenario, non-GBR services are not
congested and AQM brings little gain.
6.2 Information to Be Collected

None
6.3 Network Planning

None
6.4 Deploying AQM

6.4.1 Deployment Requirements
This feature has no requirements for the operating environment or transmission networking.
If AQM is required, operators must purchase and activate the following license.

eRAN
Feature License Control Item Name
LOFD-001027 Active Queue Management(AQM) Active Queue Management(AQM)
6.4.2 Data Preparation

This section describes generic data and scenario-specific data to be collected. Generic data is
necessary for all scenarios and must always be collected. Scenario-specific data is collected only when
necessary for a specific scenario.
There are three types of data sources:
 Network plan (negotiation required): Parameters are planned by operators and negotiated with the
EPC or peer transmission equipment.
 Network plan (negotiation not required): Parameters are planned and set by operators.
 User-defined: Parameters are set as required by users.
Generic Data
The following table describes the parameters that must be set in the CellAlgoSwitch managed object
(MO) to configure the AQM algorithm switch.
Parameter Name Parameter ID Source Setting Description

Local cell ID CellAlgoSwitch.LocalCellId Network plan (negotiation Set this parameter to
not required) the local ID of the cell
where the AQM
algorithm will be
enabled.
AQM algorithm CellAlgoSwitch.AqmAlgoSwitch Network plan (negotiation Set this parameter
switch not required) based on the network
plan.
Scenario-specific Data
None
6.4.3 Initial Configuration

Configuring a Single eNodeB Using the GUI
Configure a single eNodeB using the Configuration Management Express (CME) graphical user
interface (GUI) based on the collected data described in section 6.4.2 "Data Preparation." For details,
see the procedure for configuring a single eNodeB on the CME GUI described in eNodeB Initial
Configuration Guide.
Configuring eNodeBs in Batches

To configure eNodeBs in batches, perform the following steps:

eRAN
Step 1 On the GUI, set the parameters listed in the table for a specific scenario in this section, and save
the parameter settings as a user-defined template.
The parameters are the same as those described in section 6.4.2 "Data Preparation."
Step 2 Fill in the summary data file with the name of the user-defined template.
The parameter settings in the user-defined template will be applied to the eNodeBs after you import
the summary data file into the CME.
----End
For descriptions of the user-defined template and summary data file and also the detailed procedure for
configuring eNodeBs in batches, see eNodeB Initial Configuration Guide.
MO Parameter Group Name Parameter

CELLALGOSWITCH CellAlgoSwitch LocalCellId, AQM algorithm switch
Configuring a Single eNodeB Using MML Commands

To enable AQM, run the MOD CELLALGOSWITCH command with the AqmAlgoSwitch check box
selected under the AQM algorithm switch parameter.
6.4.4 Commissioning
None
6.4.5 Activation Observation

Before the observation, ensure that:
 The downlink throughput of the user's computer is controlled under 10 Mbit/s. The downlink
throughput can be controlled by decreasing the cell bandwidth or increasing the number of UEs in the
cell.
 The user's computer can normally access the network, connect to the download server, and run FTP
download services.
 Multiple large files whose sizes are larger than 1 GB and multiple small files are available on the
server for the download.
NOTE
Whether a file is a small file depends on the downlink throughput of the user's computer. If the latency of downloading a
file is within 10 seconds when one or more large files and the file are downloaded simultaneously, the file is a small file.
The observation procedure is as follows:

Step 1 Run the MOD CELLALGOSWITCH command with the AqmAlgoSwitch check box selected
under the AQM algorithm switch parameter. Then, enable the computer to access the network.
Step 2 Download one or more large files and a small file simultaneously. Then, record the small file
download latency. Repeat the test and average the recorded values as the small file download
latency with AQM enabled.
Step 3 Run the MOD CELLALGOSWITCH command with the AqmAlgoSwitch check box cleared
under the AQM algorithm switch parameter. Then, enable the computer to reaccess the
network.

eRAN
Step 4 Download one or more large files and a small file simultaneously. Then, record the small file
download latency. Repeat the test and average the recorded values as the small file download
latency with AQM disabled.
Step 5 Compare the two average values and verify that the time of small file download is shortened
when AQM is enabled.
----End
6.4.6 Reconfiguration
None
6.4.7 Deactivation
To disable AQM, run the MOD CELLALGOSWITCH command with the AqmAlgoSwitch check box
cleared under the AQM algorithm switch parameter.
6.5 Performance Optimization

None
6.6 Troubleshooting
6.6.1 Fault Description
AQM is enabled but brings no gain to the system.
6.6.2 Fault Handling

The troubleshooting procedure is as follows:
Step 1 Download one or more large files, and perform a ping operation simultaneously.
Step 2 Maintain the test for at least 2 minutes, and monitor the ping delay changes. If the delay is
shorter than or equal to 350 ms, download more large files to increase the delay.
Step 3 When the delay reaches 350 ms, start downloading a small file or open a web page. If the test
result still indicates no gains from AQM, contact Huawei technical support.
----End

eRAN
AQM 7 Parameters
7 Parameters
Table 7-1 Parameter description
MO Parameter ID MML Command Feature ID Feature Name Description
CellAlgoSwit AqmAlgoSwit MOD LOFD-001027 / Active Queue Meaning:Indicates the

ch ch CELLALGOSWIT TDLOFD-0010 Management(AQ switch that is used to
CH 27 M) enable and disable the
Active Queue
LST Management (AQM)
CELLALGOSWIT algorithm.
CH
If this switch is set to
ON, the AQM function
is enabled to prevent
or control congestion.
The length of the
PDCP packet queue is
maintained at a
relatively small value
to help achieve an
appropriate trade-off
between throughput
and time latency.
If this switch is set to
OFF, the AQM function
is disabled.
GUI Value
Range:AqmAlgoSwitc
h
Unit:None
Actual Value
Range:AqmAlgoSwitc
h
Default
Value:AqmAlgoSwitch:
Off
CellAlgoSwit LocalCellId LST None None Meaning:Indicates the

ch CELLALGOSWIT local ID of the cell. It
CH uniquely identifies a
cell within a BS.
MOD
CELLALGOSWIT GUI Value
CH Range:0~17
Unit:None
Actual Value
Range:0~17

eRAN
AQM 7 Parameters
MO Parameter ID MML Command Feature ID Feature Name Description

Default Value:None

eRAN
AQM 8 Counters
8 Counters
There are no specific counters associated with this feature.

eRAN
AQM 9 Glossary
9 Glossary
For the acronyms, abbreviations, terms, and definitions, see Glossary.

eRAN
AQM 10 Reference Documents
10 Reference Documents
This chapter lists the reference documents related to AQM:
[1] eNodeB MO Reference
[2] eNodeB Initial Configuration Guide


AQM (eRAN3.0 - 04)

Uploaded by

Copyright:

Available Formats

AQM (eRAN3.0 - 04)

Uploaded by

Document Information

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

AQM (eRAN3.0 - 04)

Uploaded by

Copyright:

Available Formats

AQM

HUAWEI TECHNOLOGIES CO., LTD.

Trademarks and Permissions

Huawei Technologies Co., Ltd.

2 Overview of AQM ......................................................................................................................2-1

5 Impact on the Network.............................................................................................................5-1

6 Engineering Guidelines ...........................................................................................................6-1

Issue 04 (2013-05-20) Huawei Proprietary and Confidential i

1.2 Intended Audience

1.3 Change History

Change Type Change Description Parameter Change

Issue 04 (2013-05-20) Huawei Proprietary and Confidential 1-1

Change Type Change Description Parameter Change

Change Type Change Description Parameter Change

Change Type Change Description Parameter Change

Change Type Change Description Parameter Change

Issue 04 (2013-05-20) Huawei Proprietary and Confidential 1-2

Issue 04 (2013-05-20) Huawei Proprietary and Confidential 2-1

Issue 04 (2013-05-20) Huawei Proprietary and Confidential 3-1

4.1 Required Features

4.2 Mutually Exclusive Features

4.3 Affected Features

Issue 04 (2013-05-20) Huawei Proprietary and Confidential 4-1

5 Impact on the Network

5.1 Impact on System Capacity

5.2 Impact on Network Performance

Issue 04 (2013-05-20) Huawei Proprietary and Confidential 5-1

6.1 When to Use AQM

6.2 Information to Be Collected

6.3 Network Planning

6.4 Deploying AQM

Issue 04 (2013-05-20) Huawei Proprietary and Confidential 6-1

Feature License Control Item Name

LOFD-001027 Active Queue Management(AQM) Active Queue Management(AQM)

6.4.2 Data Preparation

Parameter Name Parameter ID Source Setting Description

6.4.3 Initial Configuration

Configuring eNodeBs in Batches

Issue 04 (2013-05-20) Huawei Proprietary and Confidential 6-2

MO Parameter Group Name Parameter

Configuring a Single eNodeB Using MML Commands

6.4.5 Activation Observation

The observation procedure is as follows:

Issue 04 (2013-05-20) Huawei Proprietary and Confidential 6-3

6.5 Performance Optimization

6.6.2 Fault Handling

Issue 04 (2013-05-20) Huawei Proprietary and Confidential 6-4

CellAlgoSwit AqmAlgoSwit MOD LOFD-001027 / Active Queue Meaning:Indicates the

CellAlgoSwit LocalCellId LST None None Meaning:Indicates the

Issue 04 (2013-05-20) Huawei Proprietary and Confidential 7-1

MO Parameter ID MML Command Feature ID Feature Name Description

Issue 04 (2013-05-20) Huawei Proprietary and Confidential 7-2

Issue 04 (2013-05-20) Huawei Proprietary and Confidential 8-1

Issue 04 (2013-05-20) Huawei Proprietary and Confidential 9-1

Issue 04 (2013-05-20) Huawei Proprietary and Confidential 10-1

You might also like