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8/13/2019 Half Rate & AMR Description
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13.May 2006
HUAWEI TECHNOLOGIES Co., Ltd.
www.huawei.com
HUAWEI Confidential
Security Level: Internal
Huawei HR and AMR
Introduction
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Huawei Half Rate
Huawei AMR
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HR - Assignment Principle
Different MSs support different rates. The assignment principle of radio resource is as
follows:
For the MSs that support full rate and half rate, the full rate is assigned preferentially
to improve the voice quality when the network is idle. The half rate is assigned
preferentially to hold more users when the network is busy. Whether the
network is busy or not is judged by comparing the channel seizure ratio andconfigured threshold (TCH Traffic Thrsh (%)): If the channel seizure ratio is
high than the threshold, the network is busy. Otherwise, the network is idle.
For the half rate call, the single channel is assigned preferentially to reduce the
fragment.
When the rate is enough to meet the service requirement, the channels on the TRXs
that do not allow the rate adjustment are assigned preferentially. The channelson the TRXs that allow rate adjustment are reserved for later use. This way
can ensure the maximum use of the channel resources.
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Two Channel Allocation Strategies
There are two channel assignment strategies: MSC channel assignment
strategy and BSC channel assignment strategy.
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.
For the call that uses the half rate preferentially, the single channel isassigned 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.
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Rate Adjustment Principle
The adjustment principle is as follows:
Before assign the channel, determine whether to adjust the rate
or not according to the channel resources in the cell. If yes,
assign the channel to the current call after adjusting the rate.
That is, adjust the rate in real time.
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Assignment request for full rate only
Full rate available
Assignmentrequest for TCHF
only
Assign full rate
channel
Couple channel
available
Convert couple channel tofull rate channel and then
assign the converted
channel
Initiate intracell handover toform couple channel, and
then convert the couple
channel to full rate channelto assign
Requestreject
Yes
Yes
Yes
No
No
No
more than one halfrate channel
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Assignment request for half rate
only/preferentially
Single channel available
Half rateassignment
request
Assign half ratechanel
Couple channel availableAssign the half rate
channel on thecouple channel
Full rate channelavailable
Convert the full rate channel
into couple channel and thenassign the half rate channel
on the couple channel
Assignmentfails
Yes
Yes
Yes
No
No
No
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HR Related Parameters
Channel seizure ratio = (Average num. of busy TCHF + Average num. of busy TCHH/2)/
(Average num. of availabe TCHF + Average num. of available TCHH /2) x 100
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HR Related Traffic Statistic
BSC Measurement Function
Cell Measurement Function (2)
Half Rate Call Drop Measurement
Half Rate Receiving Quality Measurement
Half Rate Receiving Level Measurement
Overlaid/Underlaid Subcell Measurement
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Huawei Half Rate
Huawei AMR
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AMR - DefinitionThe Adaptive Multi Rate (AMR)is a set of multiple voice Codec algorithms. The BTS
and MS can automatically choose a proper Codec algorithm according to the actualradio environment to adjust the rate. Thus the voice quality can be improved.
Different Codec algorithm generates different rate voice code stream.
The AMR is only used in voice service. It is not used in the data service or signaling
service. Thus, the AMR is not considered when process the signaling of data
service or signaling service.
Full Rate AMRIt supports full rate channel AMR voice coding and decoding and includes 8 voice
rates: 12.2k (GSM EFR), 10.2k, 7.95k, 7.40k (IS-641), 6.70k, 5.90k, 5.15k, 4.75k;
The full rate AMR can adjust the coding rate according to the radio quality indication
(RQI). The coding rate is adjusted in the active coding set (ACS).
Half Rate AMR
It supports half rate channel AMR voice coding and decoding and includes 5 voice
rates: 7.40k (IS-641), 6.70k, 5.90k, 5.15k, 4.75k;
The half rate AMR can adjust the coding rate according to the radio quality
indication (RQI). The coding rate is adjusted in the ACS.
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AMR FR MOS
Exper iment 1a - Test Results
1.0
2.0
3.0
4.0
5.0
Condi t ions
MOS
EFR12.210.27.957.46.75.95.154.75
EFR 4.01 4.01 3.65 3.05 1.5312.2 4.01 4.06 4.13 3.93 3.44 1.4610.2 4.06 3.96 4.05 3.80 2.047.95 3.91 4.01 4.08 3.96 3.26 1.437.4 3.83 3.94 3.98 3.84 3.11 1.396.7 3.77 3.80 3.86 3.29 1.875.9 3.72 3.69 3.59 2.205.15 3.50 3.58 3.44 2.434.75 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
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AMR HR MOS
Experim ent 1b - Test Results
1.0
2.0
3.0
4.0
5.0
Condit ions
MOS
EFR7.957.46.75.95.154.75FRHR
EFR 4.21 4.21 3.74 3.34 1.587.95 4.11 4.04 3.96 3.37 2.53 1.607.4 3.93 3.93 3.95 3.52 2.74 1.786.7 3.94 3.90 3.53 3.10 2.22 1.215.9 3.68 3.82 3.72 3.19 2.57 1.335.15 3.70 3.60 3.60 3.38 2.85 1.844.75 3.59 3.46 3.42 3.30 3.10 2.00FR 3.50 3.50 3.14 2.74 1.50
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
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AMR call set up process
Y
Deciding whether to assign
channel that supports AMR
function
Finishes AMR call set up
Deciding whether to
support AMR functionNormal Call
N
BSC receives the assigningrequest sent by MSC
Y
NNormal Call
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Start and Close AMR Service Activated coding set
You can set different ACS, coding rate adjustment threshold and hysteresis and
initial coding rate according to the cells.
Add cell-level call statistical metrics.
TC query
You can inquire the TC support capability through the BSC maintenance console:
whether it supports the various voice Codec algorithms
Dynamic configuration function
Codec Mode Report
You can inquire the current coding mode used by a specified channel in real time.
The system outputs the coding mode and C/I information (RQI) used during the
inquiry period.
Intracell HR
FR HandoverThe system controls the balance between the cell capacity and the quality through
the intra-cell HR-FR handover based on RQI.
Different Power Control Methods
The AMR call and the non-AMR call use different power control parameters but the
same algorithm.
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Call Process and Intracell Parameters
No. Parameter
1 TRX supports AMR or not
2 Active coding set
3 Full rate UL rate adjustment threshold (0 - 3)
4 Full rate UL rate adjustment hysteresis (0 - 3)
5 Full rate DL rate adjustment threshold (0 - 3)
6 Full rate DL rate adjustment hysteresis (0 - 3)
7 Half rate UL rate adjustment threshold (0 - 3),
8 Halfrate UL rate adjustment hysteresis (0 - 3),
9 Half rate DL rate adjustment threshold (0 - 3)
10 Half rate DL rate adjustment hysteresis (0 - 3)
No. Parameter
1 Intracell TCHF-TCHH handover statistics time
2 Intracell TCHF-TCHH lasting time
3 Handover threshold from TCHF to TCHH
4 Handover threshold from TCHH to TCHF
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Circuit Pool 27
Service Type Explanation
FR speech version1 Full rate voice version 1, usually called FR.
FR speech version2 Full rate voice version 2, usually called EFR.
FR speech version3 Full rate voice version 3, codec algorithm used in full rate channel.
HR speech version1 Half rate voice version 1, usually called HR.
HR speech version3 Half rate voice version 3, codec algorithm used in half rate channel.
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Typical Case
A user starts AMR function as follows:
In the MSC side, choose the Full rate speech version 3 and Half
rate speech version 3.
Configure the A interface protocol phase as Phase II+.
Configure the A interface circuit to support the AMR function.
It is recommended to configure the circuit pool as 27.
Configure the TRX to support the AMR function.
Configure the AMR call processing parameter.
Configure the AMR power control parameter.
Configure intracell TCHF-TCCH handover data.
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Related Traffic Statistic
No. Item name
1 Successful TCH assignments(FR SV1, excluding directed retry)
2 Successful TCH assignments(FR SV2, excluding directed retry)
3 Successful TCH assignments(FR SV3, excluding directed retry)
2. Cell performance measurement (2)
No. Item name
1 Successful TCH assignments(HR SV1, excluding directed retry)
2 Successful TCH assignments(HR SV2, excluding directed retry)
3 Successful TCH assignments(HR SV3, excluding directed retry)
1. Cell performance measurement
3. Call allocation by TA measurement function
4. Average RQI based on TA value