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www.huawei.com
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved.
英文标题 :40-47pt
副标题 :26-30pt
字体颜色 : 反白内部使用字体 :
FrutigerNext LT Medium
外部使用字体 : Arial
中文标题 :35-47pt
字体 : 黑体 副标题 :24-28pt
字体颜色 : 反白字体 : 细黑体
GSM Multiple Rate Algorithm
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page3
Objectives
Upon completion of this course, you will be able to:
Understand the multiple rate algorithm function and
types.
Master the parameters of multiple rate algorithm.
Be able to configure the data of multiple rate
algorithm.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page4
Full Rate
Traffic Channel (TCH) carries coded voice data. The full-
rate TCH is initially adopted to carry information at the
gross rate 22.8Kbit/s. The information contains the source
coding rate of 13Kbit/s.
As technologies develop, the enhanced full rate, half rate,
multiple rate and other coding are introduced.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page5
Speech Version
Speech version indicates the voice coding
technology.
Full RateFull Rate
Speech
Version1FR
Speech
Version2EFR
Speech
Version3AMR
Half RateHalf Rate
Speech
Version1HR
Speech
Version2/
Speech
Version3AMR
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page6
Circuit Pool Function
“Circuit pool number” actually represents the circuit
type, indicating the support capability of the voice
codec.
Different circuit pool numbers can support different
voice rates.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page7
Circuit Pool FunctionCircuit Pool
NumberSupported Rate
1FR speech version 1 ; FR data (12, 6, 3.6 Kbps)
2HR speech version 1 ; HR data (6, 3.6 Kbps)
3
FR speech version 1 ; FR data (12, 6, 3.6 Kbps) ;HR speech version 1 ; HR data (6, 3.6 Kbps)
4FR speech version 2 ; FR data (12, 6, 3.6 Kbps)
5FR speech version 1 ; FR speech version 2FR data (12, 6, 3.6 Kbps)
6
FR speech version 2 ; FR data (12, 6, 3.6 Kbps)HR speech version 1 ; HR data (6, 3.6 Kbps)
7
FR speech version 1 ; FR speech version 2FR data (12, 6, 3.6 Kbps) ; HR speech version 1HR data (6, 3.6 Kbps)
Circuit Pool Number
Supported Rate
23FR speech version 3 ; HR speech version 3
24FR speech version 3 ; FR data (12, 6, 3.6 Kbps)HR speech version 3
25
FR speech version 1 ; FR speech version 2FR speech version 3 ; FR data (12, 6, 3.6 Kbps)HR speech version 3
27
FR speech version 1 ; FR speech version 2FR speech version 3 ; FR data (12, 6, 3.6 Kbps)HR speech version 1 ; HR speech version 3HR data (6, 3.6 Kbps)
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page8
Call Signaling ProcessingBSC
ASS REQ
Channel ACT
Channel ACT ACK
ASS CMD
SABM
UAEST IND
ASS CMPASS CMP
MS MSCBTS
Setup
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page9
Call Signaling MessageSetup Message
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page10
Call Signaling MessageASS REQ Message
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page11
Call Signaling MessageChannel Act Message
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page12
Call Signaling MessageASS CMD Message
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page13
Call Signaling MessageASS CMP Message
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page14
Contents
1. EFR
2. HR
3. AMR
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page15
The Function of EFR The Enhanced Full Rate (EFR) is a speech coding scheme
with an enhanced full rate. Using this coding scheme, you can provide services with better speech quality.
In the wireless communications system, the EFR applies to only speech services and is irrelevant to data services or signaling services.
The EFR function adopts the CELP( Code Excited Linear Predictive Coding) coding scheme, thus improves the quality of the speech signal.
When EFR is adopted, the transmission rate of the
speech signal of an MS on the air interface is 12.2 kbit/s.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page16
EFR Call Set-up Flow
Common call (FR)
EFR call
Speech version in theassignment request is EFR
Start
Finish
Yes
NoWhether support EFRin the current cell?
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page17
Call Signaling MessageChannel Act Message
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page18
Call Signaling MessageASS CMD Message
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page19
Call Signaling ProcessingASS CMP Message
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page20
EFR Data Configuration Configure “Cell Attributes/Call Control/Advanced/Access
Control /Speech Version”
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page21
Contents
1. EFR
2. HR
3. AMR
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page22
The Function of HR The half rate voice coding uses a new voice coding algorithm
called VCELPVCELP ( (Vector-Sum Excited Linear PredictionVector-Sum Excited Linear Prediction) ) to
reduce the voice coding rate to half that of full rate voice
service. Thus, one physical channel that can only support one
call under the full rate can support two calls under half rate.
If the half rate service is used, the voice capacity expands
twice without adding TRXs. By adopting half rate service, the
operator can fully use the current network to expand the
system capacity. This saves the cost and eases the spectrum
use.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page23
The Function of HR
T T T T T T T T T T T S T T T T T T T T T T T T IT
T T T T T T S T T T T T T
t t t t t t t t t t t t s
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page24
The Function of HR
Single : When a timeslot is used as two TCH/H channels, one
TCH/H channel is busy and another is idle, this idle
TCH/H channel is called single channel or channel
fragment or fragment.
Idle Busy
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page25
The Function of HR Couple : When a timeslot is used as two TCH/H
channels, and these two channels are both free,
this timeslot is called a couple.
Idle Idle
Busy Busy
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page26
The Function of HR
I: Idle B : Busy
I B B B B B B BBIB BB B BB
I I B B B B B BBBB BB B BB
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page27
Channel Assignment Strategies If the half rate function is used, when BSC receives the
“assignment request” from the MSC, it will decides to use the
channel allocation algorithm according to channel
assignment strategy specified in the data configuration.
MSC channel assignment strategy
Assign the channel according to the MSC request. If the request from
MSC is "TCHF preferred", assign the full rate channel preferentially. If it
is "TCHH preferred", assign the half rate channel preferentially.
BSC channel assignment strategy
When the assignment request sent from MSC is "Full rate TCH
preferred" or" Half rate TCH preferred", BSC assigns the proper
channel according to the availability of idle full rate channel in the cell
and the allowance of MSC.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page28
Channel Assignment Strategies The BSC channel allocation strategy is the default strategy.
That is, when the network is idle, the full rate is used,
otherwise, the half rate is used.
For the call that uses the half rate preferentially, the single
channel is assigned preferentially to reduce the fragment.
If a cell has multiple TRXs, the channels on the TRXs that
do not allow the rate adjustment are assigned
preferentially.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page29
Rate Adjustment Flow If the channel assignment request is to choose the full rate
channel only:
When there is idle full rate channel, assign the channel directly.
When there is no idle full rate channel in the cell, but there is idle
couple channel, convert the couple channel to full rate channel and
then assign the converted full rate channel.
When there is no idle full rate channel and idle couple channel in
the cell, but there is idle single channel, check whether the number
of single channel in the cell is more than one. If yes, initiate
intracell handover to form a couple channel and then convert the
couple channel to full rate to assign.
Otherwise, reject the assignment request.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page30
Rate Adjustment Flow
Yes
Yes
Yes
No
No
No
Assignment requestfor TCHF only
Full rate available?
Couple channelavailable?
More than one halfrate channel?
Request reject
Assign full rate channel
Convert couple channel to fullrate channel and then assign
the converted channel
Initiate intra-cell handover toform couple channel, and thenconvert the couple channel to
full rate channel to assign
Start
End
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page31
Rate Adjustment Flow If the channel assignment request is to half rate only :
When there is idle single channel in the cell, assign the idle half rate
channel on the single channel directly.
When there is no idle single channel in the cell, but there is idle
couple channel in the cell, assign the idle half rate channel on the
couple channel.
When there is no idle single channel and idle couple channel in the
cell, but there is idle full rate channel in the cell, convert the full rate
channel into couple channel and then assign the idle half rate
channel on the couple channel.
Otherwise, reject the request.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page32
Rate Adjustment Flow
Yes
Yes
Yes
No
No
No
Half rate only assignment request
Single channel available?
Couple channel available?
Full rate channel available?
Assignment fails
Assign half rate channel
Assign the half rate channelon the couple channel
Convert the full rate channel into couple channel and then assign the half rate channel on it
Start
End
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page33
Rate Adjustment Flow If the channel assignment request is to choose the full rate
channel preferentially:
When there is idle full rate channel in the cell, assign it directly.
When there is no idle single channel in the cell, but there is idle
couple channel in the cell, convert the couple channel into full rate
channel and then assign it.
When there is no idle full rate channel and couple channel in the cell,
check whether the number of adjustable half rate channel in the cell is
more than one. If yes, initiate intracell handover to form a couple
channel and then convert the couple channel to full rate to assign
Otherwise, assign the idle half rate channel on the single channel.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page34
Rate Adjustment Flow
Yes
Yes
No
No
No
Yes
Assign request for full rate preferentially
Full rate available?
Couple channel available?
More than one half rate channel?
Assign full rate channel
Convert the couple channel into full rate channel to assign
Form couple channel by intracell handover and then convert couple channel into full rate to assign
Start
End
Assign half rate channel
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page35
Rate Adjustment Flow If the channel assignment request is to half rate preferentially:
When there is idle single channel in the cell, assign the idle half rate
channel on the single channel directly.
When there is no idle single channel in the cell, but there is idle
couple channel in the cell, assign the idle half rate channel on the
couple channel.
When there is no idle single channel and idle couple channel in the
cell, but there is idle full rate channel in the cell, convert the full rate
channel into couple channel and then assign the idle half rate
channel on the couple channel.
Otherwise, assign the idle full rate channel.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page36
Rate Adjustment Flow
Yes
Yes
Yes
No
No
No
Prefer half rate assignment request
Single channel available?
Couple channel available?
Full rate channel available?
Assignment TCH/F
Assign half rate channel
Assign the half rate channelon the couple channel
Convert the full rate channel into couple channel and then assign the half rate channel on it
Start
End
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page37
Call Signaling MessageChannel Act Message
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page38
Call Signaling MessageASS CMD Message
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page39
Call Signaling MessageASS CMP Message
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page40
HR Data Configuration Configure “Site Attributes\multiplexing mode”(1:1 or 2:1 is
recommended)
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page41
HR Data Configuration Configure “Call Control\Advanced\Access Control”
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page42
HR Data Configuration Configure “Cell Attributes\Other Parameter\Public Channel
Control\ Support Half Rate”
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page43
HR Data Configuration Configure “Cell Attributes\TRX Attributes\Channel
Attributes\ Channel Type”
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page44
HR Data Configuration Configure “Cell Attributes\TRX Attributes\Device
Attributes\ TCH Rate Adjust Allow”
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page45
HR Data Configuration Configure “Cell Attributes\Channel Parameter\Basic Channel
Management Parameters\Enhanced TCH Adjust Allowed”
Configure “Cell Attributes\Channel Parameter\Advanced\TCH Traffic Busy Threthold”
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page46
HR Data Configuration
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page47
HR Data Configuration
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page48
HR Data Configuration
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page50
Contents
1. EFR
2. HR
3. AMR
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page51
Contents
3. AMR
3.1 AMR Overview
3.2 AMR Impact on the Network Quality
3.3 AMR Call&Handover Procedure and Parameter
Introduction
3.4 AMR Optimization and Maintenance Strategy
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page52
AMR Overview AMR (Adaptive Multi Rate) is a new voice coding technique
after EFR, FR, and HR.
Its core thought is to automatically select appropriate codec
algorithm and constantly select the voice coding rate
according to change of the uplink/downlink signal quality.
BER
MOS
Codec1
Codec2
Codec3
AMR
Different codec algorithms
produce voice code streams
in different rates so as to get
the optimal balance between
voice quality and system
capacity.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page53
AMR Overview AMR is a collection of multiple voice codec algorithms. AMR
allows the BTS and the MS to select appropriate codec algorithms
according to the actual situation of the radio environment.
AMR is applicable only to the voice service of the wireless
communication system. It is not related to data service and
signaling service.
You need to obtain license to use AMR. The license is applied on
one cell.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page54
AMR Overview AMR Voice Coding Mode (Rates)
Full-rate AMR supports eight voice
coding modes.
Half-rate AMR supports five voice
coding modes.
AMR Activated Voce Coding Set
(ACS)
ACS defines the set of changes of
the voice coding rates during a
call. This set contains one~four
coding modes.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page55
AMR FRExperiment 1a - Test Results
1.0
2.0
3.0
4.0
5.0
Conditions
M OS
EFR12.210.27.957.46.75.95.154.75
EFR 4.01 4.01 3.65 3.05 1.53
12.2 4.01 4.06 4.13 3.93 3.44 1.46
10.2 4.06 3.96 4.05 3.80 2.04
7.95 3.91 4.01 4.08 3.96 3.26 1.43
7.4 3.83 3.94 3.98 3.84 3.11 1.39
6.7 3.77 3.80 3.86 3.29 1.87
5.9 3.72 3.69 3.59 2.20
5.15 3.50 3.58 3.44 2.43
4.75 3.50 3.52 3.43 2.66
No Errors C/I=16 dB C/I=13 dB C/I=10 dB C/I= 7 dB C/I= 4 dB C/I= 1 dB
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page56
AMR HR
1.0
2.0
3.0
4.0
5.0
Conditions
MOS
EFR7.957.46.75.95.154.75FRHR
EFR 4.21 4.21 3.74 3.34 1.58
7.95 4.11 4.04 3.96 3.37 2.53 1.60
7.4 3.93 3.93 3.95 3.52 2.74 1.78
6.7 3.94 3.90 3.53 3.10 2.22 1.21
5.9 3.68 3.82 3.72 3.19 2.57 1.33
5.15 3.70 3.60 3.60 3.38 2.85 1.84
4.75 3.59 3.46 3.42 3.30 3.10 2.00
FR 3.50 3.50 3.14 2.74 1.50
HR 3.35 3.24 2.80 1.92
No Errors C/I=19 dB C/I=16 dB C/I=13 dB C/I=10 dB C/I= 7 dB C/I= 4 dB
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page57
Contents
3. AMR
3.1 AMR Overview
3.2 AMR Impact on the Network Quality
3.3 AMR Call&Handover Procedure and Parameter
Introduction
3.4 AMR Optimization and Maintenance Strategy
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page58
Impact of AMR on Network Quality(1) Impact of AMR on Voice Quality
According to the simulation result, when C/I is greater than
6, the voice quality performance in descending order is FR
AMR, EFR, HR AMR, FR, and HR. It can be seen that AMR can
effectively improve network quality.
The voice quality performance of HR AMR is the similar to
FR, However, radio bandwidth occupied by HR AMR in the
Um interface is only half of that of FR. Therefore, HR AMR
can not only ensure the good voice quality, but also
increase the system capacity effectively.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page59
Impact of AMR on Network Quality(2) Impact of AMR on Network Coverage
AMR Network Coverage Performance
AMR has excellent anti-interference capability. Under the same
FER, AMR supports lower CIR than non-AMR. Therefore AMR has
better coverage performance.
AMR Coverage Bottleneck
In the actual coverage capability of AMR is determined by the
coverage capability of the SACCH.
In application, the data——[RLT] and [SACCH Multi-Frames] should
be set to higher values for AMR channels to increase the
robustness of the SACCH. Thus the network coverage performance
of AMR is improved and the call drop rate is reduced.
Enhanced signaling link technique is available to improve it.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page60
Impact of AMR on Network Quality(3) Impact of AMR on the Network Capacity
AMR can equivalently increase the total spectrum bandwidth of the Radio System
AMR can tolerate lower C/I. With AMR, the number of cells in a single frequency reuse cluster is smaller and the spectrum reuse degree is higher, compared with non-AMR.
AMR can reduce the radio bandwidth for a single user When HR AMR is used, the number of channels doubles, while the voice quality does
not drop obviously.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page61
Impact of AMR on Network Quality(4) Impact of AMR on KPIs
Traffic volume
The voice codec of AMR has low requirement for CIR, so in weak coverage areas
where calls could not be made before, AMR calls can be made, thus reducing
the possibility of user’s hang-up. Therefore, AMR can improve network traffic
volume.
Call drop rate
AMR only optimizes the performance of the voice frames. In weak coverage
areas, because voice frames can be correctly decoded, users will not hand up a
phone, however, because the SACCH frames cannot be correctly decoded, the
RLT times out, leading to call drop. Therefore with AMR, the call drop rate can
rise, while enhanced signaling link technique is available to improve it.
Handover
AMR increases the width and depth of the network coverage. But C/I is low in
these weak coverage areas and the receive quality in the measurement report
is poor, triggering BQ handover. Therefore with AMR, the number of BQ
handovers can rise.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page62
Contents
3. AMR
3.1 AMR Overview
3.2 AMR Impact on the Network Quality
3.3 AMR Call&Handover Procedure and Parameter
Introduction
3.4 AMR Optimization and Maintenance Strategy
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page63
AMR Call&Handover Procedure and Data Configuration In the BSC6000, the following AMR parameters need to be set
1. AMR basic data parameters
2. ACS and starting mode
3. Coding rate adjustment threshold and hysteresis (full rate)
4. Coding rate adjustment threshold and hysteresis (half rate)
5. Radio link timeout (RLT) and SACCH Multi-Frames
6. AMR radio channel management parameters
7. AMR handover parameters
8. AMR power control parameters
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page64
AMR Parameter Introduction(1)1. AMR basic data
parameters
To active AMR, enable
“full-rate speech coding
algorithm 3” and “half-
rate speech coding
algorithm 3” on the MSC
side.
In addition, configure the
corresponding interface
flag as GSM_PHASE_2+.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page65
AMR Parameter Introduction(1)1. AMR basic data parameters
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page66
AMR Call Set-up Procedure
Y
Finishes AMR call set up
BSC decides whether to support AMR function
Normal CallN
BSC receives the assigning request sent by MSC
BSC decides whether to assign channel that
supports AMR function
Relationship between voice type and voice version
FR : Full rate /speech version 1EFR: Full rate /speech version 2FR AMR : Full rate /speech version 3
HR : Half rate /speech version 1 HR AMR : Half rate /speech version 3Normal Call
N
Y
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page67
Call Signaling MessageChannel Act Message
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Call Signaling MessageASS CMD Message
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Call Signaling MessageASS CMP Message
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page70
AMR Parameter Introduction(2)
2. ACS and Starting Mode
ACS should be set basing on the actual radio
environment. However, because of the complexity of
the actual radio environment and the randomness of
users' behaviors, not all of the coding modes can be
listed. Generally, the worst coding mode, the best
coding mode, and two coding modes between them
are selected.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page71
AMR Parameter Introduction(2)
01
23
2. ACS and Starting Mode
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page72
AMR Parameter Introduction(2)
012
2. ACS and Starting Mode
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page73
AMR Parameter Introduction(3)3. Coding Rate Adjustment Threshold and Hysteresis
(FR)
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page75
AMR Parameter Introduction(4)4. Coding Rate Adjustment Threshold and Hysteresis
(HR)
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page77
AMR Parameter Introduction(4) Principles of AMR Codec Mode Adjustment
The criteria for conversion of the voice codec mode is CODEC MODE 1~4
corresponding to THR_1~3 and HYST1~3
Assume that the active codec mode is CODEC_MODE_3 for example. When C/I is
greater than THR_3+HYST_3, the codec mode is switched to CODEC_MODE_4;
when C/I is smaller than THR_2, the codec mode is switched to CODEC_MODE_2
CODEC_MODE_4
CODEC_MODE_3
CODEC_MODE_2
CODEC_MODE_1
C/I
THR_1 + HYST_1 = THR_MX_Up(1)
THR_1 = THR_MX_Dn(2)
THR_2 = THR_MX_Dn(3)
THR_2 + HYST_2 = THR_MX_Up(2)
THR_3 = THR_MX_Dn(4)
THR_3 + HYST_3 = THR_MX_Up(3) The adjustment of the practical voice codec rate can only changes step by step, while can not jump over several steps for sudden changing of C/I
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page78
Principle of AMR Coding Mode Adjustment The uplink coding mode is detected by the BTS.
If the BTS discovers that the configured threshold is achieved, it initiates “Coding Mode Change” command.
After the conversion of the coding mode is completed, the MS responds with a “Coding Mode Indication” message.
AMR ( FR/HR ) UL Codec Mode Adjustment
Coding Mode Change
Coding Mode Indication
BTS detects that RQI reaches the threshold
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page79
Principle of AMR Coding Mode Adjustment The downlink coding is detected by the MS(The same algorithm
is used).
When the MS detects that the threshold is achieved, it initiates
“Coding Mode Request”.
The BTS either ignores or immediately responds to the request
depending on the actual situation.
Upon completion, the BTS sends a “Coding Mode Indication”
message to the MS.
Coding Mode Request
Coding Mode Indication
MS detects that RQI reaches the threshold
AMR ( FR/HR ) DL Codec Mode Adjustment
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page80
AMR Parameter Introduction(5)5. Radio Link Timeout (RLT) and SACCH Multi-Frames
To increase the robustness of the SACCH channel, to
improve the AMR network coverage performance, and
to lower the call drop rate, in practice the RLT and
SACCH Multi-Frames should be set higher.
On the other side, Enhanced Signaling Link
Technique is available to improve it.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page81
Enhanced Signaling Link Technique
Repeated Downlink
FACCH – Improve the probability of
the MS receiving the FACCH
frames in the poor radio
enviroment
Repeated SACCH
– Improve the robustness of
SACCH links
BSC Version: BSC6000V9R8C12
BTS Version: BTSV3R8C03
MS Version: The MS that supports 3GPP R6
Repeated ACCH consists of Repeated Downlink FACCH and Repeated SACCH
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page82
Enhanced Signaling Link Technique Repeated Downlink FACCH Technical Principle
Enable BSS to transmit the FACCH frames repeatedly when the
measurement result of the downlink link is lower than the threshold
configured.
The repetition mechanism is as follows
0 1 2 3 4 5 6 7 8 9 10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
F S IFF F
resentresent
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page83
Enhanced Signaling Link Technique Implementation of Repeated
Downlink FACCH Technical
1. Enable the cell-level switch
“Repeated Downlink FACCH ”
and configure “Repeated
Downlink FACCH Threshold”
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page84
Enhanced Signaling Link Technique Implementation of Repeated Downlink FACCH Technical
2. BSC decodes the capability of the MS support” Repeated
ACCH ”, and then informs BTS about the Repeated ACCH
Capability of the MS via “Channel Active” message when
activizing TCH channel.
3. BTS determines whether to start to send repeated FACCH
messages by comparing the receive quality provided in the
downlink MR and the “Repeated Downlink FACCH
Threshold”.
Copyright © 2010 Huawei Technologies Co., Ltd. All rights reserved. Page85
Enhanced Signaling Link Technique Repeated SACCH Technical Principle
Add SRO(SACCH Repetition Order) indication bit on the downlink
SACCH, and SRR(SACCH Repetition Request) indication bit on the uplink
SACCH.
Upon the failure to decode an SACCH frame, BTS sets the SRO to 1,
requesting MS to resend the SACCH frame.
Upon the failure to decode an SACCH frame, MS sets the SRR to 1,
requesting BTS to resend the SACCH frame.
SRO
SRR
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Enhanced Signaling Link Technique Implementation of Repeated
SACCH Technical
1. Enable the cell-level switch
“Repeated Downlink FACCH ”
2. BSC decodes the capability of
the MS support” Repeated
ACCH ”, and then informs BTS
about the Repeated ACCH
Capability of the MS via
“Channel Active” message
when activising TCH channel.
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Enhanced Signaling Link Technique Implementation of Repeated SACCH Technical
3. Suppose MS supports ”Repeated ACCH Capability”
when BTS receives the uplink SACCH frame in which SRR=1, the
BTS will resend SACCH frames excluding short message until
SRR=0
If BTS fails to decode an uplink SACCH, BTS sets SRO=1,
requesting MS to resend the uplink SACCH frame until SRO=0
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AMR Parameter Introduction(6)6. AMR Radio Channel Management Parameters
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AMR Parameter Introduction(7)
7. AMR Handover Parameters
AMR handover is the intra-cell handover between FR AMR and HR
AMR.
Via HR-FR channel conversion, which is based on RQI and channel
occupation ratio, control strategy for balancing between the capacity
and quality of the cell is provided.
When configure the handover parameters, [AMR TCH/H Prior
Allowed] and [AMR TCH/H Prior Cell Load Threshold] should
be taken into account.
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AMR Handover Procedure AMR handover refers to the intra-cell handover between FR AMR and HR AMR
basing on the RQI.
The AMR handover provides control strategy of capacity-quality balance within a
cell.
The AMR handover is implemented through the intra-cell handover procedure.
If in P seconds of N seconds:RQI > [F2H HO Threshold], then intra-cell handover indication from FR AMR to HR AMR is initiated;
RQI < [H2F HO Threshold], then intra-cell handover indication from HR AMR to FR AMAR is initiated.
Relationship between RQI and C/I : RQI = 2*C/I
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AMR Handover ProcedureBegin
Is [Intracell F-H HO Allowed] Yes ?
Yes
Is current channel TCH & version3?
No
A: Cell load > [AMR TCH/H Prior
Cell Load Threshold]
During [Penalty Time
after AMR TCHF-H HO
Fail(s)]?
Yes
Yes
Is current channel FR?
Satisfy P/N rule?Trigger internal
cellAMR handover
Yes
NoEnd
RQI/2 >[F2H HO th] & A
RQI/2 <[H2F HO th] End
Yes Yes
NoNo
No
No
No
Yes
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AMR Parameter Introduction(7)7. AMR Handover Parameters
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AMR Parameter Introduction(7)7. AMR Handover Parameters
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AMR Parameter Introduction(8)8. AMR Power Control Parameters
Different power control thresholds are set for AMR calls and non-AMR calls. AMR calls are transmitted in lower power than non-AMR calls.
The setting principles are as follows: Set lower “AMR UL/DL RX_LEV Upper/Lower Threshold” for AMR calls
than those for non-AMR calls.
Set higher “AMR UL/DL Qual. Upper/lower Threshold” for AMR calls than those for non-AMR calls.
Keep other AMR power control parameters consistent with normal power control parameters.
In practice, need to consider the setting of normal power control parameters to adjust the AMR power control parameters.
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AMR Parameter Introduction(8)8. AMR Power Control Parameters
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AMR Parameter Introduction(8)8. AMR Power Control Parameters
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Contents
3. AMR
3.1 AMR Overview
3.2 AMR Impact on the Network Quality
3.3 AMR Call&Handover Procedure and Parameter
Introduction
3.4 AMR Optimization and Maintenance Strategy
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AMR Optimization&Maintenance Strategy(1)
No. Performance Counters
1 Speech Version 1 Completed Assignments(Excluding Directed Retry)(TCHF)
2 Speech Version 2 Completed Assignments(Excluding Directed Retry)(TCHF)
3 Speech Version 3 Completed Assignments(Excluding Directed Retry)(TCHF)
4 Speech Version 1 Completed Assignments(Excluding Directed Retry)(TCHH)
5 Speech Version 2 Completed Assignments(Excluding Directed Retry)(TCHH)
6 Speech Version 3 Completed Assignments(Excluding Directed Retry)(TCHH)
Half rate speech version 2 actually does not exist. Therefore the half rate speech
version 2 TCH assignments (excluding direct retry) should be always zero
Traffic Statistics–AMR Call Ratio Calculation
If you need to calculate AMR (speech version 3) call ratio,
according to the number of TCH assignment successes of
various speech versions under full rate/half rate.
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AMR Optimization&Maintenance Strategy(2)
Adding cell-level AMR call counters.
Cell-level AMR call counters are added in the Call
Measurement.
Radio quality indication (RQI) performance statistics
TRX-level RQI performance statistics function by TA
distribution is provided.
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Summary
In this course , we have learned : The function of EFR, HR, AMR
The signaling assignment flow of EFR, HR, AMR
Data configuration of EFR, HR, AMR
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