eRAN
AQM Feature Parameter Description
Issue
01
Date
2018-04-10
HUAWEI TECHNOLOGIES CO., LTD.
Copyright © Huawei Technologies Co., Ltd. 2018. 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.
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All other trademarks and trade names mentioned in this document are the property of their respective holders.
Notice
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Huawei Technologies Co., Ltd.
Address:
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Contents
1 Change History
1.1 eRAN13.1 01 (2018-04-10)
1.2 eRAN13.1 Draft B (2018-03-30)
1.3 eRAN13.1 Draft A (2018-01-15) (FDD)
2 About This Document
2.1 General Statements
2.2 Applicable RAT
2.3 Features in This Document
3 Overview
4 AQM
4.1 Principles
4.2 Network Analysis
4.2.1 Benefits
4.2.2 Impacts
4.3 Requirements
4.3.1 Licenses
4.3.2 Software
4.3.3 Hardware
4.3.4 Others
4.4 Operation and Maintenance
4.4.1 Data Configuration
4.4.1.1 Data Preparation
4.4.1.2 Using MML Commands
4.4.1.3 Using the CME
4.4.2 Activation Verification
4.4.3 Network Monitoring
5 Parameters
6 Counters
7 Glossary
8 Reference Documents
1 Change History
This chapter describes changes not included in the "Parameters", "Counters", "Glossary", and "Reference
Documents" chapters. These changes include:
•
Technical changes
Changes in functions and their corresponding parameters
•
Editorial changes
Improvements or revisions to the documentation
1.1 eRAN13.1 01 (2018-04-10)
This issue includes the following changes.
Technical Changes
None
Editorial Changes
Deleted the descriptions of MLBFD-12100242 Active Queue Management (AQM).
1.2 eRAN13.1 Draft B (2018-03-30)
This issue includes the following changes.
Technical Changes
Change Description
Converted MLBFD-12100242 Active Queue
Management (AQM) into a commercial feature.
Parameter Change
None
Editorial Changes
Added deactivation command examples. For details, see 4.4.1.2 Using MML Commands.
1.3 eRAN13.1 Draft A (2018-01-15) (FDD)
This issue introduces the following changes to eRAN12.1 02 (2017-06-29).
Technical Changes
Change Description
Added support for MLBFD-12100242 Active Queue
Management (AQM) on DBS3900 LampSite and DBS5900
LampSite.
Parameter Change
None
Editorial Changes
Reorganized this document using a new template.
2 About This Document
2.1 General Statements
Purpose
This document is intended to acquaint readers with:
•
The technical principles of features and their related parameters
•
The scenarios where these features are used, the benefits they provide, and the impact they
have on networks and functions
•
Requirements of the operating environment that must be met before feature activation
•
Parameter configuration required for feature activation, verification of feature activation, and
monitoring of feature performance
NOTE:
This document only provides guidance for feature activation. Feature deployment and feature
gains depend on the specifics of the network scenario where the feature is deployed. To achieve
the desired gains, contact Huawei professional service engineers.
Software Interfaces
Any parameters, alarms, counters, or managed objects (MOs) described in this document apply only to
the corresponding software release. For future software releases, refer to the corresponding updated
product documentation.
Trial Features
Trial features are features that are not yet ready for full commercial release for certain reasons. For
example, the industry chain (terminals/CN) may not be sufficiently compatible. However, these features
can still be used for testing purposes or commercial network trials. Anyone who desires to use the trial
features shall contact Huawei and enter into a memorandum of understanding (MoU) with Huawei prior to
an official application of such trial features. Trial features are not for sale in the current version but
customers may try them for free.
Customers acknowledge and undertake that trial features may have a certain degree of risk due to
absence of commercial testing. Before using them, customers shall fully understand not only the
expected benefits of such trial features but also the possible impact they may exert on the network. In
addition, customers acknowledge and undertake that since trial features are free, Huawei is not liable for
any trial feature malfunctions or any losses incurred by using the trial features. Huawei does not promise
that problems with trial features will be resolved in the current version. Huawei reserves the rights to
convert trial features into commercial features in later R/C versions. If trial features are converted into
commercial features in a later version, customers shall pay a licensing fee to obtain the relevant licenses
prior to using the said commercial features. If a customer fails to purchase such a license, the trial
feature(s) will be invalidated automatically when the product is upgraded.
2.2 Applicable RAT
This document applies to FDD.
2.3 Features in This Document
This document describes the following FDD features.
Feature ID
LBFD-001027
Feature Name
Active Queue Management (AQM)
3 Overview
Congestion has become a bottleneck in network development due to the limitation of resource capacity
and processing capability of networks. End-to-end Transmission Control Protocol (TCP) congestion
control techniques have been the primary methods to control IP network congestion. However, edge
nodes in a network may not be able to obtain accurate information about network status in time.
Therefore, it is hard for these TCP congestion control techniques to solve all congestion problems in the
network.
To address this issue, congestion control techniques based on intermediate network nodes, such as
AQM, have been developed.
4 AQM
4.1 Principles
Huawei AQM applies to non-guaranteed bit rate (non-GBR) services.
AQM is controlled by the CellAlgoSwitch.AqmAlgoSwitch parameter.
As an IP network node, the eNodeB uses AQM to check data packet queue lengths. AQM compares the
average queue length with the minimum and maximum congestion thresholds, and then performs the
following operations based on the comparison result:
•
Average queue length ≤ Minimum congestion threshold
AQM does not drop any packets because the queue is not congested.
•
Minimum congestion threshold < Average queue length < Maximum congestion threshold
AQM drops some packets because the queue is congested to some extent. The probability of
dropping packets increases linearly with:
•
▪
The average queue length
▪
The amount of data successfully sent from the core network to the eNodeB
Average queue length ≥ Maximum congestion threshold
AQM drops every newly arrived packet because the queue is severely congested.
The minimum congestion threshold is automatically calculated by the eNodeB based on the real-time air
interface data rate.
The maximum congestion threshold is equal to the minimum congestion threshold multiplied by eight.
As shown in Figure 4-1, the red lines denote the packet loss rates and Max represents the maximum
packet loss rate of a non-GBR service in the congestion avoidance area.
Figure 4-1 AQM working areas
4.2 Network Analysis
4.2.1 Benefits
AQM offers the following benefits:
•
Proactively detects possible congestion in the queues and minimizes the congestion probability
by dropping packets.
•
Maintains shorter queues to balance the throughput and transmission delay.
•
Avoids TCP global synchronization caused by simultaneous data overflow of multiple queues.
NOTE:
TCP global synchronization happens as follows:
Data traffic is generally bursty, and data packets arrive at a queue suddenly. A large number of packets
will be dropped when the queue becomes full, or is getting close to becoming full. Upon packet loss
detection, multiple TCP senders adaptively and sharply decrease their send window. Consequently, the
packet arrival rate declines quickly and the network congestion is relieved. After detecting that the
network is no longer congested, the TCP senders start to increase transmission rates, which again results
in network congestion. In the procedure, each sender decreases and increases transmission rates
repeatedly at the same time as other senders.
It is recommended that AQM be enabled when both of the following conditions are met:
•
The average processing delay of downlink Packet Data Convergence Protocol (PDCP) service
data units (SDUs) for services carried on data radio bearers (DRBs) is larger than 500 ms per
packet.
The average processing delay of downlink PDCP SDUs for services carried on DRBs can be
monitored by dividing L.Traffic.DL.PktDelay.Time.QCI.x by L.Traffic.DL.PktDelay.Num.QCI.x,
where x indicates a QCI. For details about related counters, see Table 4-1.
•
The value of the Discard timer parameter for the QCI is larger than 500 ms.
The parameter value can be queried by running the LST RLCPDCPPARAGROUP command.
Table 4-1 Counters related to the average processing delay of downlink PDCP SDUs for services
carried on DRBs
Counter ID
Counter
1526727922
L.Traffic.DL.PktDelay.Time.QCI.6
1526727925
L.Traffic.DL.PktDelay.Time.QCI.7
1526727928
L.Traffic.DL.PktDelay.Time.QCI.8
1526727931
L.Traffic.DL.PktDelay.Time.QCI.9
1526727923
L.Traffic.DL.PktDelay.Num.QCI.6
1526727926
L.Traffic.DL.PktDelay.Num.QCI.7
1526727929
L.Traffic.DL.PktDelay.Num.QCI.8
1526727932
L.Traffic.DL.PktDelay.Num.QCI.9
In the following scenarios, AQM offers no gains or could even have slightly negative effects:
•
AQM helps reduce only TCP traffic on a bearer when both TCP and User Datagram Protocol
(UDP) services are carried on the bearer.
•
AQM drops packets randomly during network congestion. Therefore, if AQM drops packets of
interactive services, user experience in these services deteriorates.
•
The eNodeB does not enter the congestion state when the data rates of cell edge users (CEUs)
fluctuate due to interference, and therefore AQM offers no obvious gains for such UEs.
•
Dropping packets causes throughput fluctuation, and the fluctuation is more obvious when there
are only a small number of TCP connections, for example, one or two connections.
•
Non-GBR services of a UE will not be congested when the downlink UE throughput on a bearer
exceeds 30 Mbit/s. In this scenario, AQM offers no obvious gains.
4.2.2 Impacts
Network Impacts
AQM has the following impacts on throughput:
•
•
The cell throughput and the throughput of some UEs fluctuate.
▪
If a cell has both CEUs and cell center users (CCUs), AQM will decrease the throughput
of CEUs because CEU services are easily congested. CCU services are rarely
congested, and therefore AQM will increase the throughput of CCUs. This increased
throughput is larger than the decreased throughput for CEUs. In this case, the overall cell
throughput increases.
▪
If a cell has only CEUs or CCUs, AQM has little impact on cell throughput.
The throughput of GBR services increases.
If GBR and non-GBR services coexist in a cell and the actual GBR service rate is less than the
subscribed GBR service rate, the decrease in the throughput of non-GBR services possibly
brings more scheduling opportunities to GBR services. This may increase the throughput of GBR
services.
Function Impacts
None
4.3 Requirements
4.3.1 Licenses
There are no license requirements.
4.3.2 Software
Prerequisite Functions
None
Mutually Exclusive Functions
None
4.3.3 Hardware
Base Station Models
No requirements
Boards
No requirements
RF Modules
No requirements
4.3.4 Others
None
4.4 Operation and Maintenance
4.4.1 Data Configuration
4.4.1.1 Data Preparation
Table 4-2 describes the parameters used for function activation.
Table 4-2 Parameters used for activation
Parameter Name
AQM algorithm switch
Parameter ID
CellAlgoSwitch.AqmAlgoSwitch
4.4.1.2 Using MML Commands
Activation Command Examples
//Turning on the AQM algorithm switch
MOD CELLALGOSWITCH: LocalCellId=0, AqmAlgoSwitch=AqmAlgoSwitch-1;
Deactivation Command Examples
//Turning off the AQM algorithm switch
MOD CELLALGOSWITCH: LocalCellId=0, AqmAlgoSwitch=AqmAlgoSwitch-0;
4.4.1.3 Using the CME
For detailed operations, see CME-based Feature Configuration.
4.4.2 Activation Verification
Before the verification, ensure that:
•
The downlink throughput of the UE is lower than 10 Mbit/s. The downlink throughput can be
controlled by decreasing the bandwidth of a cell or by increasing the number of UEs in the cell.
•
The UE properly accesses the network, connects to the download server, and runs FTP
download services.
•
Multiple large files that are larger than 1 GB and multiple small files are available on the server for
downloading.
NOTE:
Turn
The size of a small file can be determined based on the air interface throughput of the UE. If the
time for downloading a file while downloading one or multiple large files is within 10s, the file is a
small file.
The verification procedure is as follows:
1. Run the MOD CELLALGOSWITCH command with the AqmAlgoSwitch option of
the CellAlgoSwitch.AqmAlgoSwitch parameter deselected to disable AQM. Then, enable the
UE to access the given cell.
2. Download one or more large files and the small files simultaneously. Then, record the small file
download latency. Repeat the test and average the recorded values. The average value works as
the small file download latency with AQM disabled.
3. Run the MOD CELLALGOSWITCH command with the AqmAlgoSwitch option of
the CellAlgoSwitch.AqmAlgoSwitch parameter selected to enable AQM. Then, enable the UE
to re-access the given cell.
4. Download one or more large files and the small files simultaneously. Then, record the small file
download latency. Repeat the test and average the recorded values. The average value works as
the small file download latency with AQM enabled.
5. Compare the two average values and verify that the small file download latency is shortened after
AQM is enabled.
4.4.3 Network Monitoring
Benefit Monitoring
After AQM is enabled, the average processing delay of downlink PDCP SDUs for services carried on
DRBs may decrease slightly.
The average processing delay of downlink PDCP SDUs for services carried on DRBs can be monitored
by dividing L.Traffic.DL.PktDelay.Time.QCI.x by L.Traffic.DL.PktDelay.Num.QCI.x, where x indicates a
QCI. For details about related counters, see Table 4-1.
Impact Monitoring
The number of downlink PDCP SDUs discarded for services carried on DRBs may increase
slightly. Table 4-3 describes related counters.
Table 4-3 Counters related to the number of downlink PDCP SDUs discarded for services carried on
DRBs
Counter ID
Counter Na
1526726863
L.PDCP.Tx.Disc.Trf.SDU.QCI.6
1526726869
L.PDCP.Tx.Disc.Trf.SDU.QCI.7
1526726875
L.PDCP.Tx.Disc.Trf.SDU.QCI.8
1526726881
L.PDCP.Tx.Disc.Trf.SDU.QCI.9
5 Parameters
Table 5-1 Parameters
MO
Parameter
ID
MML Command
Feature ID
CellAlgoSw AqmAlgoSw MOD
LBFDCELLALGOSWI 001027/TDLB
itch
itch
TCH
FD-001027
LST
CELLALGOSWI
TCH
Feature
Name
Description
Active
Queue
Managem
ent
(AQM)
Meaning:
Indicates
whether to
enable the
Active Queue
Management
(AQM)
algorithm.
If this switch is
on, the AQM
function is
enabled to
prevent or
control
congestion. The
length of the
data
transmission
queue is
maintained at a
relatively small
value to help
achieve an
appropriate
trade-off
between
throughput and
latency.
If this switch is
off, the AQM
function is
disabled. This
parameter
applies only to
LTE FDD and
LTE TDD.
GUI Value
Range:
AqmAlgoSwitch
Unit: None
Parameter
ID
MO
MML Command
Feature ID
Feature
Name
Description
Actual Value
Range:
AqmAlgoSwitch
Default Value:
AqmAlgoSwitch
:Off
6 Counters
Table 6-1 Counters
Counter ID
Counter Name
Counter
Descriptio
n
Feature
ID
Feature
Name
152672686
3
L.PDCP.Tx.Disc.Trf.SDU.QCI.6
Number of
downlink
PDCP
SDUs
discarded
for services
carried on
DRBs with
a QCI of 6
in a cell
Multimode:
None
GSM:
None
UMTS:
None
LTE:
LBFD002008
TDLBFD
-002008
LBFD002025
TDLBFD
-002025
NR: None
Radio
Bearer
Managemen
t
Radio
Bearer
Managemen
t
Basic
Scheduling
Basic
Scheduling
152672686
9
L.PDCP.Tx.Disc.Trf.SDU.QCI.7
Number of
downlink
PDCP
SDUs
discarded
for services
carried on
DRBs with
a QCI of 7
in a cell
Multimode:
None
GSM:
None
UMTS:
None
Radio
Bearer
Managemen
t
Radio
Bearer
Managemen
t
Counter ID
Counter Name
Counter
Descriptio
n
Feature
ID
Feature
Name
LTE:
LBFD002008
TDLBFD
-002008
LBFD002025
TDLBFD
-002025
NR: None
Basic
Scheduling
Basic
Scheduling
152672687
5
L.PDCP.Tx.Disc.Trf.SDU.QCI.8
Number of
downlink
PDCP
SDUs
discarded
for services
carried on
DRBs with
a QCI of 8
in a cell
Multimode:
None
GSM:
None
UMTS:
None
LTE:
LBFD002008
TDLBFD
-002008
LBFD002025
TDLBFD
-002025
NR: None
Radio
Bearer
Managemen
t
Radio
Bearer
Managemen
t
Basic
Scheduling
Basic
Scheduling
152672688
1
L.PDCP.Tx.Disc.Trf.SDU.QCI.9
Number of
downlink
PDCP
SDUs
discarded
for services
carried on
DRBs with
a QCI of 9
in a cell
Multimode:
None
GSM:
None
UMTS:
None
LTE:
LBFD002008
Radio
Bearer
Managemen
t
Radio
Bearer
Managemen
t
Basic
Scheduling
Counter ID
Counter Name
Counter
Descriptio
n
Feature
ID
Feature
Name
TDLBFD Basic
-002008 Scheduling
LBFD002025
TDLBFD
-002025
NR: None
152672792
2
L.Traffic.DL.PktDelay.Time.QCI.6
Total
processing
delay of
downlink
PDCP
SDUs for
DRB
services
with the
QCI of 6 in
a cell
Multimode:
None
GSM:
None
UMTS:
None
LTE:
LBFD002008
TDLBFD
-002008
LBFD002025
TDLBFD
-002025
NR: None
Radio
Bearer
Managemen
t
Radio
Bearer
Managemen
t
Basic
Scheduling
Basic
Scheduling
152672792
3
L.Traffic.DL.PktDelay.Num.QCI.6
Number of
successfull
y
transmitted
downlink
PDCP
SDUs for
DRB
services
with the
QCI of 6 in
a cell
Multimode:
None
GSM:
None
UMTS:
None
LTE:
LBFD002008
TDLBFD
-002008
Radio
Bearer
Managemen
t
Radio
Bearer
Managemen
t
Basic
Scheduling
Basic
Scheduling
Counter ID
Counter Name
Counter
Descriptio
n
Feature
ID
Feature
Name
LBFD002025
TDLBFD
-002025
NR: None
152672792
5
L.Traffic.DL.PktDelay.Time.QCI.7
Total
processing
delay of
downlink
PDCP
SDUs for
DRB
services
with the
QCI of 7 in
a cell
Multimode:
None
GSM:
None
UMTS:
None
LTE:
LBFD002008
TDLBFD
-002008
LBFD002025
TDLBFD
-002025
NR: None
Radio
Bearer
Managemen
t
Radio
Bearer
Managemen
t
Basic
Scheduling
Basic
Scheduling
152672792
6
L.Traffic.DL.PktDelay.Num.QCI.7
Number of
successfull
y
transmitted
downlink
PDCP
SDUs for
DRB
services
with the
QCI of 7 in
a cell
Multimode:
None
GSM:
None
UMTS:
None
LTE:
LBFD002008
TDLBFD
-002008
LBFD002025
Radio
Bearer
Managemen
t
Radio
Bearer
Managemen
t
Basic
Scheduling
Basic
Scheduling
Counter ID
Counter Name
Counter
Descriptio
n
Feature
ID
Feature
Name
TDLBFD
-002025
NR: None
152672792
8
L.Traffic.DL.PktDelay.Time.QCI.8
Total
processing
delay of
downlink
PDCP
SDUs for
DRB
services
with the
QCI of 8 in
a cell
Multimode:
None
GSM:
None
UMTS:
None
LTE:
LBFD002008
TDLBFD
-002008
LBFD002025
TDLBFD
-002025
NR: None
Radio
Bearer
Managemen
t
Radio
Bearer
Managemen
t
Basic
Scheduling
Basic
Scheduling
152672792
9
L.Traffic.DL.PktDelay.Num.QCI.8
Number of
successfull
y
transmitted
downlink
PDCP
SDUs for
DRB
services
with the
QCI of 8 in
a cell
Multimode:
None
GSM:
None
UMTS:
None
LTE:
LBFD002008
TDLBFD
-002008
LBFD002025
TDLBFD
-002025
NR: None
Radio
Bearer
Managemen
t
Radio
Bearer
Managemen
t
Basic
Scheduling
Basic
Scheduling
Counter ID
Counter Name
Counter
Descriptio
n
Feature
ID
Feature
Name
152672793
1
L.Traffic.DL.PktDelay.Time.QCI.9
Total
processing
delay of
downlink
PDCP
SDUs for
DRB
services
with the
QCI of 9 in
a cell
Multimode:
None
GSM:
None
UMTS:
None
LTE:
LBFD002008
TDLBFD
-002008
LBFD002025
TDLBFD
-002025
NR: None
Radio
Bearer
Managemen
t
Radio
Bearer
Managemen
t
Basic
Scheduling
Basic
Scheduling
152672793
2
L.Traffic.DL.PktDelay.Num.QCI.9
Number of
successfull
y
transmitted
downlink
PDCP
SDUs for
DRB
services
with the
QCI of 9 in
a cell
Multimode:
None
GSM:
None
UMTS:
None
LTE:
LBFD002008
TDLBFD
-002008
LBFD002025
TDLBFD
-002025
NR: None
Radio
Bearer
Managemen
t
Radio
Bearer
Managemen
t
Basic
Scheduling
Basic
Scheduling
152672946
6
L.RLC.FirstPacketDelay.NonGBR.Index Number of Multitimes delay mode:
0
of the first None
non-GBR
Active
Queue
Counter ID
Counter Name
Counter
Descriptio
n
RLC
packets
ranges
within
index 0
Feature
ID
Feature
Name
GSM:
None
UMTS:
None
LTE:
LBFD001027
LAOFD001001
NR: None
Managemen
t (AQM)
LTE-A
Introduction
152672946
7
L.RLC.FirstPacketDelay.NonGBR.Index Number of
times delay
1
of the first
non-GBR
RLC
packets
ranges
within
index 1
Multimode:
None
GSM:
None
UMTS:
None
LTE:
LBFD001027
LAOFD001001
NR: None
Active
Queue
Managemen
t (AQM)
LTE-A
Introduction
152672946
8
L.RLC.FirstPacketDelay.NonGBR.Index Number of
times delay
2
of the first
non-GBR
RLC
packets
ranges
within
index 2
Multimode:
None
GSM:
None
UMTS:
None
LTE:
LBFD001027
LAOFD001001
NR: None
Active
Queue
Managemen
t (AQM)
LTE-A
Introduction
Counter ID
Counter Name
Counter
Descriptio
n
Feature
ID
Feature
Name
152672946
9
L.RLC.FirstPacketDelay.NonGBR.Index Number of
times delay
3
of the first
non-GBR
RLC
packets
ranges
within
index 3
Multimode:
None
GSM:
None
UMTS:
None
LTE:
LBFD001027
LAOFD001001
NR: None
Active
Queue
Managemen
t (AQM)
LTE-A
Introduction
152672947
0
L.RLC.FirstPacketDelay.NonGBR.Index Number of
times delay
4
of the first
non-GBR
RLC
packets
ranges
within
index 4
Multimode:
None
GSM:
None
UMTS:
None
LTE:
LBFD001027
LAOFD001001
NR: None
Active
Queue
Managemen
t (AQM)
LTE-A
Introduction
7 Glossary
For the acronyms, abbreviations, terms, and definitions, see Glossary.
8 Reference Documents
None