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ZGO-04-02-009 FACCH/SACCH Feature Guide
Repeated
ZGO-04-02-009 Repeated FACCH/SACCH
ZGO-04-02-009 Repeated FACCH/SACCH Version V1.00
Date
Author
2010-10-30
Approved By
Remarks Not open to the Third Party
© 2010 ZTE Corporation. All rights reserved. ZTE CONFIDENTIAL: This document contains proprietary information of ZTE and is not to be disclosed or used without the prior written permission of ZTE. Due to update and improvement of ZTE products and technologies, information in this document is subjected to change without notice.
ZTE Confidential Proprietary
© 2010 ZTE CORPORATION. All rights reserved.
I
ZGO-04-02-009 Repeated FACCH/SACCH
TABLE OF CONTENTS 1
Feature Attribute ............................................................................................. 1
2 2.1 2.2
Overview ......................................................................................................... 1 Feature Introduction.......................................................................................... 1 Correlation with Other Features ........................................................................ 4
3 3.1 3.2 3.2.1 3.3
Technical Description .................................................................................... 4 FACCH Retransmission Process ...................................................................... 4 SACCH Retransmission Process ...................................................................... 7 Downlink SACCH Retransmission Process ...................................................... 9 Uplind SACCH Retransmission Process ......................................................... 10
4 4.1 4.2
Parameters and Configurations................................................................... 11 Parameter List ................................................................................................ 11 Parameter Configurations ............................................................................... 12
5 5.1 5.2
Related Counters and Alarms ...................................................................... 12 Related Counters ............................................................................................ 12 Related Alarms ............................................................................................... 12
6 6.1 6.2 6.3
Engineering Guide ........................................................................................ 13 Application Scenario ....................................................................................... 13 Configuration Description................................................................................ 13 Network Impact............................................................................................... 13
7
Abbreviation.................................................................................................. 13
8
Reference Document .................................................................................... 14
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II
ZGO-04-02-009 Repeated FACCH/SACCH
FIGURES Figure 2-1 The Link Performance Comparison in AMR Voice Channel and Control Channel ............................................................................................................................................... 2 Figure 2-2 ............................................................................................................................... 2 Figure 2-3 Decoding Success Rate Curve of SACCH Retransmission ................................. 3 Figure 3-1 Explanation of FACCH retransmission parameter in protocol .............................. 5 Figure 3-2 Performance Comparison -1 ............................................................................... 6 Figure 3-3 Performance Comparison -1 ............................................................................... 6 Figure 3-4 Explanation of SACCH retransmission parameter in protocol .............................. 7 Figure 3-5 Performance Comparison of Repeated SACCH -1 .............................................. 8 Figure 3-6 Performance Comparison of Repeated SACCH -2 .............................................. 8 Figure 4-1 Window for Repeated ACCH ............................................................................. 12
TABLES Table 4-1 Parameter List .................................................................................................... 11
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III
ZGO-04-02-009 Repeated FACCH/SACCH
1
Feature Attribute iBSC Version: [iBSC V6.20] BTS Version: [Apply to the SDR platform only] Attribute:Property: [Optional function] Related Network Element: Involved or
NE Name
Not
MS
√
BTS
√
BSC
√
MSC
-
MGW
-
SGSN
-
GGSN
-
HLR
-
Special Requirement R6 based MS is required
Dependent Function: [Apply to the SDR platform only] Exclusive Function:[None] Note:[None]
2
Overview
2.1
Feature Introduction When using AMR, it can function normally under lower C/I because the higher coding robust. Therefore, if the network supports AMR, the performance of FACCH and SACCH
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1
ZGO-04-02-009 Repeated FACCH/SACCH
are very important for the network performance entirely. The comparison performance of TCH, SACCH, FACCH is shown in Figure 2-1.
Figure 2-1
The Link Performance Comparison in AMR Voice Channel and Control
Channel
From Figure 1, FACCH and the highest rate AMR-FR 12.2K have the same link performances. When FER of SACCH link is 1%, the C/I it needs to be 2dB higher than that of AMR-FR 12.2 K. Furthermore, FACCH or SACCH will not use FER to measure whether the channel could function or not. The criterion is whether it could decode signaling correctly. The relation figures of FACCH and SACCH retransmission and control command decoding success probability are shown in Fig 2-2, 2-3.
Figure 2-2
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ZGO-04-02-009 Repeated FACCH/SACCH
Figure 2-3
Decoding Success Rate Curve of SACCH Retransmission
From figure 2-2 and 2-3, adopting retransmission SACCH and FACCH can greatly improve the possibility of decoding signaling message correctly. It can make signaling channels and traffic channels working to reach the performance of control channels and AMR traffic channels in the same C/I environment.
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ZGO-04-02-009 Repeated FACCH/SACCH
2.2
Correlation with Other Features This feature has the function correlation of this features: ZGO-01-01-003 Adaptive Multi-Rate (AMR) Codec.
3
Technical Description In order to match performance of AMR traffic channel to make the signaling channel and traffic channel work under the same C/I situation. Retransmission mechanism is adopted for dedicated signaling FACCH and SACCH. FACCH and SACCH retransmission can greatly improve the success rate of signaling decoding and handover, minimize the call drop. SACCH retransmission depends on MS. If the “Repeat ACCH Capability” of MS is “1”, which indicates by the MS Classmark 3 in the “Classmark Change” massage, meaning MS supports FACCH retransmission and BSS can retransmit the demand frame or response frame of LAPDm; If not, BSS can only retransmit demand frame of LAPDm. On SACCH, if the “Repeat ACCH Capability” of MS is 1, BTS can accept the MS retransmission request and begin to retransmit, or retransmit actively according to the measurement report; otherwise handled as normal way.
3.1
FACCH Retransmission Process According to downlink measurement report, if received signal level is lower than the threshold,
BSS will retransmit FACCH block after sending the latter 8 or 9 (there is
SACCH frame or idle frame between two FACCH) TDMA frames of FACCH block containing the first case of LAPDm. BTS side can send repeatedly any command frames on FACCH; if MS indicates itself “Repeated ACCH Capability” 1, BTS side can also send repeatedly response frames to FACCH.
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ZGO-04-02-009 Repeated FACCH/SACCH
If MS decodes FACCH successfully, find the same block have been received and it has agreement on protocol with the separation of current FACCH block, MS will not send the frame to its LAPDm protocol for further handling. If MS decodes FACCH and finds this frame has not been received before, MS will send this frame to LAPDm protocol for further handling. If FACCH decoding fails before and now, the gap between them complies with protocol, then combine the two decoding and recoding. If recoding succeed, decode results will be sent to LAPDm protocol for further handling. Figure 3-1
Explanation of FACCH retransmission parameter in protocol
Repeated ACCH Capability (1 bit field) This field indicates whether the MS supports Repeated SACCH and Repeated Downlink FACCH (see 3GPP TS 44.006 [76]). It is coded as follows:
0
The mobile station does not support Repeated SACCH
1
The mobile station supports Repeated SACCH and Repeated Downlink
FACCH An MS that only supports Repeated Downlink FACCH shall set this bit field to „0‟. As shown in Fig 3-1, R6 cell phones add some description on the support of ACCH Capability function. For cell phones not supporting repeated FACCH, retransmission FACCH messages will receive reject frame. For the system simulation of repeated FACCH, as shown in figure 3-2 and 3-3, in figure 3-2, if FER=0.1, C/I(FACCH)=5.2dB, then C/I(Repeated FACCH)=2.6dB; in figure 3-3, if FER=0.1, C/I(FACCH)=5.8dB, then C/I(Repeated FACCH)=2.8dB. TU3/TU50 suggests the mobile speed which has no impact upon the performance comparison. As a conclusion, with the repeated FACCH applied in the network, the performance is enhanced effectively.
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ZGO-04-02-009 Repeated FACCH/SACCH
Figure 3-2
Performance Comparison -1
Figure 3-3
Performance Comparison -1
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ZGO-04-02-009 Repeated FACCH/SACCH
3.2
SACCH Retransmission Process SACCH retransmission begin to resend only for SAPI=0 of SACCH message. The parameters explanation of SACCH retransmission in protocol is shown in Fig 3-4. Figure 3-4
Explanation of SACCH retransmission parameter in protocol
When MS support repeated SACCH, it is meaningful for downlink SRO (SACCH repetition Order) and uplink SRR (SACCH Repetition Request) in SACCH L1 head. SR0=1, it means BSS side want MS to resend the SACCH of last frame. SRR=1, it means MS side want BSS to resend the SACCH of last frame.
For the system simulation of repeated SACCH, the performance comparisons are as shown in figure 3-5 and figure 3-6.
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ZGO-04-02-009 Repeated FACCH/SACCH
Figure 3-5
Performance Comparison of Repeated SACCH -1
Figure 3-6
Performance Comparison of Repeated SACCH -2
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ZGO-04-02-009 Repeated FACCH/SACCH
In Figure3-5, if FER=0.1, C/I (FACCH)=6.0dB, then C/I (Repeated SACCH)=3.6dB, in figure 3-6, if FER=0.1, C/I(SACCH)=6.0dB, then C/I(Repeated SACCH)=2.6dB. TU3/TU50 suggests the mobile speed which does not have any impact upon the performance comparison. As a conclusion, with the repeated SACCH applied in the network, the performance is enhanced effectively.
3.2.1
Downlink SACCH Retransmission Process 1
MS Side
When MS fails to SACCH decode, it will send SACCH Repetition Request to network. After receiving it, network will decode repetition block first. If it fails again, combination decode of the last SACCH is available. If downlink SACCH block cannot be decoded successfully and the next uplink SACCH block is not retransmission message, MS will set “SACCH Repetition Request” to send SACCH retransmission in request downlink in next uplink SACCH block. If downlink SACCH block can be decoded successfully and the next uplink SACCH block is not retransmission message, MS will set “SACCH Repetition Request” to indicate no request SACCH retransmission in the next SACCH block. 2
BSS Side
If transmission downlink SACCH block is the frame of SAPI=0 and don‟t send repeatedly, this frame is the next candidate which can be sent repeatedly. If there is one repetition candidate and BSS has received the Repetiton Request of MS, BSS will send this candidate in the next SACCH block. If there is just one frame of SAPI=3 which need to be sent, BSS should delay to send the frame of SAPI=3 and give priority to send the repeated frame.
The service access point identifier (SAPI) identifies a point at which data link layer services are provided by the data link layer to a layer 3 entity (see 3GPP TS 44.005). The SAPI allows 8 service access points to be specified initially, where bit 3 of the address field octet containing the SAPI is the least significant binary digit and bit 5 is the most significant.
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ZGO-04-02-009 Repeated FACCH/SACCH
The SAPI values are allocated as shown: SAPI value 0
Related entity Call control signalling, mobility management signalling and radio resource management signalling (see 3GPP TS 44.018 and 24.010)
3
Short message service
All others
Reserved for future standardization
When receiving downlink SACCH block, MS should first decode alone. If decode is not successful, MS will combine the current frame to the last frame to decode together.
3.3
Uplind SACCH Retransmission Process 1
MS Side
If transmission uplink SACCH block is the frame of SAPI=0 and not be sent repeatedly, this frame is the retransmission candidate. If MS side has one retransmission candidate and the last correctly received SACCH Repetition Order is set to “Repeated SACCH required”, MS will retransmit this candidate in the next SACCH block. If there is SAPI=3 which need to be sent right now, MS should delay to send the frame of SAPI=3 and give priority to send the repeated frame. 2
BSS Side
When network side fails to SACCH decode, it will send SACCH Repetition Order to MS. After MS receives repetition SACCH message, it will first decode the repetition block. If fails again, it can combine the last SACCH to decode together. When MS send SACCH message of SAPI=0 and receive the repetition command again, it will resend the SACCH block in the following SACCH period. If a SAPI 3 frame was also scheduled to be sent at this next SACCH period, the BSS may delay the sending of the SAPI 3 frame by one SACCH period in order to make room for the repetition.
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ZGO-04-02-009 Repeated FACCH/SACCH
4
Parameters and Configurations
4.1
Parameter List Table 4-1
Parameter List
Full Name
Support Repeated ACCH
Abbreviation
RepeatACCH
Description
This parameter determines whether to use FACCH/SACCH retransmission function.
Value Range
Yes/No
Unit
None
Default
No
Management Object
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ZGO-04-02-009 Repeated FACCH/SACCH
4.2
Parameter Configurations Figure 4-1 Window for Repeated ACCH
5
Related Counters and Alarms
5.1
Related Counters There are no relevant counters for this function.
5.2
Related Alarms There are no relevant alarms for this function.
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ZGO-04-02-009 Repeated FACCH/SACCH
6
Engineering Guide
6.1
Application Scenario The feature is applicable when AMR is enabled. It makes sure that the signaling channel and traffic channel can work in the environment with the same C/I so that the performance of both traffic channel and AMR traffic channel can match.
6.2
Configuration Description This feature does not involve any adjustment of iBSC and BTS.
6.3
Network Impact Impacts upon the network To enhance the performance of FACCH/SACCH, increase the coding rate and decrease call drop rate. Impacts upon the NE The application of the feature will not affect the capacity of iBSC and BTS.
7
Abbreviation Abbreviations
Full Name
AFS
Adaptive Full-Rate Speech
AHS
Adaptive Half-Rate Speech
AMR
Adaptive Multi-Rate Codec
BS
Base Station
BSC
Base Station Controller
BTS
Base Transceiver Station
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ZGO-04-02-009 Repeated FACCH/SACCH
8
BSS
Base Station Systems
C/I
Carrier/Interference
FACCH
Fast Associated Control Channel
FER
Frame Error Rate
FR
Full Rate
HR
Half Rate
LAPDm
Link Access Protocol on the Dm Channel
SACCH
Slow Associated Control Channel
MOS
Mean Opinion Score
MS
Mobile Station
TCH
Traffic Channel
TDMA
Time Division Multiple Access
Reference Document [None]
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14
ZGO-04-02-009 FACCH/SACCH Feature Guide
Repeated
ZGO-04-02-009 Repeated FACCH/SACCH
ZGO-04-02-009 Repeated FACCH/SACCH Version V1.00
Date
Author
2010-10-30
Approved By
Remarks Not open to the Third Party
© 2010 ZTE Corporation. All rights reserved. ZTE CONFIDENTIAL: This document contains proprietary information of ZTE and is not to be disclosed or used without the prior written permission of ZTE. Due to update and improvement of ZTE products and technologies, information in this document is subjected to change without notice.
ZTE Confidential Proprietary
© 2010 ZTE CORPORATION. All rights reserved.
I
ZGO-04-02-009 Repeated FACCH/SACCH
TABLE OF CONTENTS 1
Feature Attribute ............................................................................................. 1
2 2.1 2.2
Overview ......................................................................................................... 1 Feature Introduction.......................................................................................... 1 Correlation with Other Features ........................................................................ 4
3 3.1 3.2 3.2.1 3.3
Technical Description .................................................................................... 4 FACCH Retransmission Process ...................................................................... 4 SACCH Retransmission Process ...................................................................... 7 Downlink SACCH Retransmission Process ...................................................... 9 Uplind SACCH Retransmission Process ......................................................... 10
4 4.1 4.2
Parameters and Configurations................................................................... 11 Parameter List ................................................................................................ 11 Parameter Configurations ............................................................................... 12
5 5.1 5.2
Related Counters and Alarms ...................................................................... 12 Related Counters ............................................................................................ 12 Related Alarms ............................................................................................... 12
6 6.1 6.2 6.3
Engineering Guide ........................................................................................ 13 Application Scenario ....................................................................................... 13 Configuration Description................................................................................ 13 Network Impact............................................................................................... 13
7
Abbreviation.................................................................................................. 13
8
Reference Document .................................................................................... 14
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II
ZGO-04-02-009 Repeated FACCH/SACCH
FIGURES Figure 2-1 The Link Performance Comparison in AMR Voice Channel and Control Channel ............................................................................................................................................... 2 Figure 2-2 ............................................................................................................................... 2 Figure 2-3 Decoding Success Rate Curve of SACCH Retransmission ................................. 3 Figure 3-1 Explanation of FACCH retransmission parameter in protocol .............................. 5 Figure 3-2 Performance Comparison -1 ............................................................................... 6 Figure 3-3 Performance Comparison -1 ............................................................................... 6 Figure 3-4 Explanation of SACCH retransmission parameter in protocol .............................. 7 Figure 3-5 Performance Comparison of Repeated SACCH -1 .............................................. 8 Figure 3-6 Performance Comparison of Repeated SACCH -2 .............................................. 8 Figure 4-1 Window for Repeated ACCH ............................................................................. 12
TABLES Table 4-1 Parameter List .................................................................................................... 11
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ZGO-04-02-009 Repeated FACCH/SACCH
1
Feature Attribute iBSC Version: [iBSC V6.20] BTS Version: [Apply to the SDR platform only] Attribute:Property: [Optional function] Related Network Element: Involved or
NE Name
Not
MS
√
BTS
√
BSC
√
MSC
-
MGW
-
SGSN
-
GGSN
-
HLR
-
Special Requirement R6 based MS is required
Dependent Function: [Apply to the SDR platform only] Exclusive Function:[None] Note:[None]
2
Overview
2.1
Feature Introduction When using AMR, it can function normally under lower C/I because the higher coding robust. Therefore, if the network supports AMR, the performance of FACCH and SACCH
ZTE Confidential Proprietary
© 2010 ZTE CORPORATION. All rights reserved.
1
ZGO-04-02-009 Repeated FACCH/SACCH
are very important for the network performance entirely. The comparison performance of TCH, SACCH, FACCH is shown in Figure 2-1.
Figure 2-1
The Link Performance Comparison in AMR Voice Channel and Control
Channel
From Figure 1, FACCH and the highest rate AMR-FR 12.2K have the same link performances. When FER of SACCH link is 1%, the C/I it needs to be 2dB higher than that of AMR-FR 12.2 K. Furthermore, FACCH or SACCH will not use FER to measure whether the channel could function or not. The criterion is whether it could decode signaling correctly. The relation figures of FACCH and SACCH retransmission and control command decoding success probability are shown in Fig 2-2, 2-3.
Figure 2-2
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ZGO-04-02-009 Repeated FACCH/SACCH
Figure 2-3
Decoding Success Rate Curve of SACCH Retransmission
From figure 2-2 and 2-3, adopting retransmission SACCH and FACCH can greatly improve the possibility of decoding signaling message correctly. It can make signaling channels and traffic channels working to reach the performance of control channels and AMR traffic channels in the same C/I environment.
ZTE Confidential Proprietary
© 2010 ZTE CORPORATION. All rights reserved.
3
ZGO-04-02-009 Repeated FACCH/SACCH
2.2
Correlation with Other Features This feature has the function correlation of this features: ZGO-01-01-003 Adaptive Multi-Rate (AMR) Codec.
3
Technical Description In order to match performance of AMR traffic channel to make the signaling channel and traffic channel work under the same C/I situation. Retransmission mechanism is adopted for dedicated signaling FACCH and SACCH. FACCH and SACCH retransmission can greatly improve the success rate of signaling decoding and handover, minimize the call drop. SACCH retransmission depends on MS. If the “Repeat ACCH Capability” of MS is “1”, which indicates by the MS Classmark 3 in the “Classmark Change” massage, meaning MS supports FACCH retransmission and BSS can retransmit the demand frame or response frame of LAPDm; If not, BSS can only retransmit demand frame of LAPDm. On SACCH, if the “Repeat ACCH Capability” of MS is 1, BTS can accept the MS retransmission request and begin to retransmit, or retransmit actively according to the measurement report; otherwise handled as normal way.
3.1
FACCH Retransmission Process According to downlink measurement report, if received signal level is lower than the threshold,
BSS will retransmit FACCH block after sending the latter 8 or 9 (there is
SACCH frame or idle frame between two FACCH) TDMA frames of FACCH block containing the first case of LAPDm. BTS side can send repeatedly any command frames on FACCH; if MS indicates itself “Repeated ACCH Capability” 1, BTS side can also send repeatedly response frames to FACCH.
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ZGO-04-02-009 Repeated FACCH/SACCH
If MS decodes FACCH successfully, find the same block have been received and it has agreement on protocol with the separation of current FACCH block, MS will not send the frame to its LAPDm protocol for further handling. If MS decodes FACCH and finds this frame has not been received before, MS will send this frame to LAPDm protocol for further handling. If FACCH decoding fails before and now, the gap between them complies with protocol, then combine the two decoding and recoding. If recoding succeed, decode results will be sent to LAPDm protocol for further handling. Figure 3-1
Explanation of FACCH retransmission parameter in protocol
Repeated ACCH Capability (1 bit field) This field indicates whether the MS supports Repeated SACCH and Repeated Downlink FACCH (see 3GPP TS 44.006 [76]). It is coded as follows:
0
The mobile station does not support Repeated SACCH
1
The mobile station supports Repeated SACCH and Repeated Downlink
FACCH An MS that only supports Repeated Downlink FACCH shall set this bit field to „0‟. As shown in Fig 3-1, R6 cell phones add some description on the support of ACCH Capability function. For cell phones not supporting repeated FACCH, retransmission FACCH messages will receive reject frame. For the system simulation of repeated FACCH, as shown in figure 3-2 and 3-3, in figure 3-2, if FER=0.1, C/I(FACCH)=5.2dB, then C/I(Repeated FACCH)=2.6dB; in figure 3-3, if FER=0.1, C/I(FACCH)=5.8dB, then C/I(Repeated FACCH)=2.8dB. TU3/TU50 suggests the mobile speed which has no impact upon the performance comparison. As a conclusion, with the repeated FACCH applied in the network, the performance is enhanced effectively.
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ZGO-04-02-009 Repeated FACCH/SACCH
Figure 3-2
Performance Comparison -1
Figure 3-3
Performance Comparison -1
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ZGO-04-02-009 Repeated FACCH/SACCH
3.2
SACCH Retransmission Process SACCH retransmission begin to resend only for SAPI=0 of SACCH message. The parameters explanation of SACCH retransmission in protocol is shown in Fig 3-4. Figure 3-4
Explanation of SACCH retransmission parameter in protocol
When MS support repeated SACCH, it is meaningful for downlink SRO (SACCH repetition Order) and uplink SRR (SACCH Repetition Request) in SACCH L1 head. SR0=1, it means BSS side want MS to resend the SACCH of last frame. SRR=1, it means MS side want BSS to resend the SACCH of last frame.
For the system simulation of repeated SACCH, the performance comparisons are as shown in figure 3-5 and figure 3-6.
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ZGO-04-02-009 Repeated FACCH/SACCH
Figure 3-5
Performance Comparison of Repeated SACCH -1
Figure 3-6
Performance Comparison of Repeated SACCH -2
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ZGO-04-02-009 Repeated FACCH/SACCH
In Figure3-5, if FER=0.1, C/I (FACCH)=6.0dB, then C/I (Repeated SACCH)=3.6dB, in figure 3-6, if FER=0.1, C/I(SACCH)=6.0dB, then C/I(Repeated SACCH)=2.6dB. TU3/TU50 suggests the mobile speed which does not have any impact upon the performance comparison. As a conclusion, with the repeated SACCH applied in the network, the performance is enhanced effectively.
3.2.1
Downlink SACCH Retransmission Process 1
MS Side
When MS fails to SACCH decode, it will send SACCH Repetition Request to network. After receiving it, network will decode repetition block first. If it fails again, combination decode of the last SACCH is available. If downlink SACCH block cannot be decoded successfully and the next uplink SACCH block is not retransmission message, MS will set “SACCH Repetition Request” to send SACCH retransmission in request downlink in next uplink SACCH block. If downlink SACCH block can be decoded successfully and the next uplink SACCH block is not retransmission message, MS will set “SACCH Repetition Request” to indicate no request SACCH retransmission in the next SACCH block. 2
BSS Side
If transmission downlink SACCH block is the frame of SAPI=0 and don‟t send repeatedly, this frame is the next candidate which can be sent repeatedly. If there is one repetition candidate and BSS has received the Repetiton Request of MS, BSS will send this candidate in the next SACCH block. If there is just one frame of SAPI=3 which need to be sent, BSS should delay to send the frame of SAPI=3 and give priority to send the repeated frame.
The service access point identifier (SAPI) identifies a point at which data link layer services are provided by the data link layer to a layer 3 entity (see 3GPP TS 44.005). The SAPI allows 8 service access points to be specified initially, where bit 3 of the address field octet containing the SAPI is the least significant binary digit and bit 5 is the most significant.
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ZGO-04-02-009 Repeated FACCH/SACCH
The SAPI values are allocated as shown: SAPI value 0
Related entity Call control signalling, mobility management signalling and radio resource management signalling (see 3GPP TS 44.018 and 24.010)
3
Short message service
All others
Reserved for future standardization
When receiving downlink SACCH block, MS should first decode alone. If decode is not successful, MS will combine the current frame to the last frame to decode together.
3.3
Uplind SACCH Retransmission Process 1
MS Side
If transmission uplink SACCH block is the frame of SAPI=0 and not be sent repeatedly, this frame is the retransmission candidate. If MS side has one retransmission candidate and the last correctly received SACCH Repetition Order is set to “Repeated SACCH required”, MS will retransmit this candidate in the next SACCH block. If there is SAPI=3 which need to be sent right now, MS should delay to send the frame of SAPI=3 and give priority to send the repeated frame. 2
BSS Side
When network side fails to SACCH decode, it will send SACCH Repetition Order to MS. After MS receives repetition SACCH message, it will first decode the repetition block. If fails again, it can combine the last SACCH to decode together. When MS send SACCH message of SAPI=0 and receive the repetition command again, it will resend the SACCH block in the following SACCH period. If a SAPI 3 frame was also scheduled to be sent at this next SACCH period, the BSS may delay the sending of the SAPI 3 frame by one SACCH period in order to make room for the repetition.
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ZGO-04-02-009 Repeated FACCH/SACCH
4
Parameters and Configurations
4.1
Parameter List Table 4-1
Parameter List
Full Name
Support Repeated ACCH
Abbreviation
RepeatACCH
Description
This parameter determines whether to use FACCH/SACCH retransmission function.
Value Range
Yes/No
Unit
None
Default
No
Management Object
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Cell
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11
ZGO-04-02-009 Repeated FACCH/SACCH
4.2
Parameter Configurations Figure 4-1 Window for Repeated ACCH
5
Related Counters and Alarms
5.1
Related Counters There are no relevant counters for this function.
5.2
Related Alarms There are no relevant alarms for this function.
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ZGO-04-02-009 Repeated FACCH/SACCH
6
Engineering Guide
6.1
Application Scenario The feature is applicable when AMR is enabled. It makes sure that the signaling channel and traffic channel can work in the environment with the same C/I so that the performance of both traffic channel and AMR traffic channel can match.
6.2
Configuration Description This feature does not involve any adjustment of iBSC and BTS.
6.3
Network Impact Impacts upon the network To enhance the performance of FACCH/SACCH, increase the coding rate and decrease call drop rate. Impacts upon the NE The application of the feature will not affect the capacity of iBSC and BTS.
7
Abbreviation Abbreviations
Full Name
AFS
Adaptive Full-Rate Speech
AHS
Adaptive Half-Rate Speech
AMR
Adaptive Multi-Rate Codec
BS
Base Station
BSC
Base Station Controller
BTS
Base Transceiver Station
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ZGO-04-02-009 Repeated FACCH/SACCH
8
BSS
Base Station Systems
C/I
Carrier/Interference
FACCH
Fast Associated Control Channel
FER
Frame Error Rate
FR
Full Rate
HR
Half Rate
LAPDm
Link Access Protocol on the Dm Channel
SACCH
Slow Associated Control Channel
MOS
Mean Opinion Score
MS
Mobile Station
TCH
Traffic Channel
TDMA
Time Division Multiple Access
Reference Document [None]
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14
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