Imm Ass Reject
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55111115 TEM/T-
Prepared: MEX/TIM Luis Batallan Approved Ericsson:
Subdirección de Calidad de Servicio y Evaluación del Desempeño de la Red
IMMEDIATE ASSIGNMENT REJECT
Approved TELCEL: Date: 2005-06-24
Rev. A
IMMEDIATE ASSIGNMENT REJECT
REVISION RECORD Date
Revision
Sections affected
2005-06-24
A
First version
Revised by Luis Ricardo Batallan
55222225
Prepared: MEX/TIM Luis Batallan
TEM/T-
Approved Ericsson: Subdirección de Calidad de Servicio y Evaluación del Desempeño de la Red
IMMEDIATE ASSIGNMENT REJECT
Approved TELCEL: Date: 2005-06-24
Rev. A
IMMEDIATE ASSIGNMENT REJECT Table of contents 1 2 3 4 5 6 UT
TU
TU
UT
TU
TU
UT
TU
UT
TU
UT
TU
UT
ABSTRACT PURPOSE OF THE DOCUMENT SCOPE INTRODUCTION TOLBS1 Analysis REFERENCES
TU
TU
UT
UT
TU
UT
TU
TU
UT
UT
UT
0 0 0 0 0 0
55333335 TEM/T-
Prepared: MEX/TIM Luis Batallan Approved Ericsson:
Subdirección de Calidad de Servicio y Evaluación del Desempeño de la Red
1
IMMEDIATE ASSIGNMENT REJECT
Approved TELCEL: Date: 2005-06-24
Rev. A
ABSTRACT U
On the analysis of Call Setup Failure has been found that for many BSC’s on Region 9 the Immediate Assignment Reject is a quite high (about 3%) and also a quite far from SDCCH congestion (about 0.5%) which would be the main reason for immediate assignment reject. This behavior trigger an in-deep analysis of the reason for immediate assignment rejects. 2
PURPOSE OF THE DOCUMENT U
The purpose of this document is to describe the problem found as reason for the increase of immediate assignment rejects. 3
SCOPE U
The TELCEL team involved on general Radio Network Optimization. 4
INTRODUCTION U
The immediate assignment reject is a message sent by the network to the MS mainly in the following situations: The IMMEDIATE ASSIGNMENT REJECT message is sent in the following situations: a) The random access is a request for 'Location Updating' or 'other procedures that can be completed with an SDCCH and NECI set to 1' and no channel available (default value for T3122=10 sec.) b) The Central Processor in BSC is overloaded (default value for T3122=20 sec.) c) Too many random accesses are received within 100 ms (more than 35 for APZ 212 11, more than 90 for APZ 212 25, more than 150 for APZ 212 20 and to be defined for APZ 212 30). (Default value for T3122=200 sec.)
Figure 1 – Immediate assignment reject
55444445 TEM/T-
Prepared: MEX/TIM Luis Batallan Approved Ericsson:
Subdirección de Calidad de Servicio y Evaluación del Desempeño de la Red
IMMEDIATE ASSIGNMENT REJECT
Approved TELCEL: Date: 2005-06-24
Rev. A
For the target BSC under study, TOLBS1, none of above situations was present and the SDCCH congestion was in average about 0.3% while the immediate assignment reject was about 3.5%. Therefore should exist another reason for the high percentage of immediate assignment reject. At this point personnel from Ericsson Local Support tracing failures at Call Setup find out that for Emergency Calls random access there is a software bug on the BSC that keeps the SDCCH resources “reserved” for emergency calls not allowing another users to access to SDCCH resources in the overlaid sub-cell even when there are SDCCH Idle in the sub-cell (overlaid) during 1 minute. The users can still accessing through SDCCH in the underlaid sub-cell, but in most of cells there is not SDCCH configured on the underlaid. The temporal solution is to add an SDCCH on underlaid sub-cell. The final solution is to load in the BSC a software correction that solves this bug or to change the release to BSS R11 where this problem has been solved. TOLBS1 ANALYSIS U
From the statistical analysis for TOLBS1 regarding immediate assignment reject and SDCCH congestion has been found that even when the SDCCH congestion attempts are not so high as the Immediate Assignment Reject.
REJCSIMMASS ⎛ ⎞ IMM _ ASS _ REJ = 100 * ⎜ ⎟[%] ⎝ REJCSIMMASS + CSIMMASS ⎠
TOLBS1 Immediate Assignment Reject vs SDCCH Attempt Congestion IMM ASS REJ
SDCCH ATT CONG
5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 19/05/05 20/05/05 21/05/05 22/05/05 23/05/05 24/05/05 25/05/05 26/05/05 27/05/05 28/05/05 29/05/05 30/05/05 31/05/05 01/06/05 02/06/05 03/06/05 04/06/05 05/06/05 06/06/05 07/06/05 08/06/05 09/06/05 10/06/05 11/06/05 12/06/05 13/06/05 14/06/05 15/06/05 16/06/05 17/06/05 18/06/05 19/06/05 20/06/05
5
Figure 2 – Immediate assignment reject vs. SDCCH attempt congestion
55555555
Prepared: MEX/TIM Luis Batallan
TEM/T-
Approved Ericsson: Subdirección de Calidad de Servicio y Evaluación del Desempeño de la Red
Approved TELCEL:
IMMEDIATE ASSIGNMENT REJECT
Date: 2005-06-24
Rev. A
The increase on Immediate Assignment reject approximately at 22/05 is concurrent with the configuration of SDCCH on overlaid sub-cell. This is also consistent with the explanation from Ericsson support about the reason for the immediate assignment reject (Emergency calls issue as stated in chapter 4).
IMMEDIATE ASSIGNMENT REJECT CSIMMASS
IMM ASS REJ
354
1
0
0
0
0
0
0
0
55
33
162
10:00:00 p.m.
11:00:00 p.m.
12:00:00 a.m.
01:00:00 a.m.
02:00:00 a.m.
03:00:00 a.m.
04:00:00 a.m.
05:00:00 a.m.
06:00:00 a.m.
07:00:00 a.m.
08:00:00 a.m.
08:00:00 p.m.
09:00:00 p.m.
948
846
291
06:00:00 p.m.
07:00:00 p.m.
3045
628
05:00:00 p.m.
03:00:00 p.m.
04:00:00 p.m.
4072
2779
02:00:00 p.m.
16273
8439
10095
01:00:00 p.m.
12:00:00 p.m.
3771
2707
10:00:00 a.m.
11:00:00 a.m.
2744
09:00:00 a.m.
10.00% 9.00% 8.00% 7.00% 6.00%
08:00:00 a.m.
180000 170000 160000 150000 140000 130000 120000 110000 100000 90000 80000 70000 60000 50000 40000 30000 20000 10000 0
REJCSIMMASS
5.00% 4.00% 3.00% 2.00% 1.00% 0.00%
Figure 3 – TOLBS1 Immediate assignment reject (23/06 to 24/06 hourly)
After the configuration of one SDCCH in underlaid (23/06 5:00 PM) there is a clear decrease on the number of Immediate Assignment Reject as can be see on the figure above.
6
REFERENCES U
-
User description, Radio Network Statistics BSS R10 (216/1553-HSC 103 12 Uen A4)
-
User Guide, BSC Object Types and Counters Rev. F1 (3/198 17-APT 210 09 Uen)
-
Call Setup Failure (Luis Batallan, CS R9)
Prepared: MEX/TIM Luis Batallan Approved Ericsson:
Subdirección de Calidad de Servicio y Evaluación del Desempeño de la Red
IMMEDIATE ASSIGNMENT REJECT
Approved TELCEL: Date: 2005-06-24
Rev. A
IMMEDIATE ASSIGNMENT REJECT
REVISION RECORD Date
Revision
Sections affected
2005-06-24
A
First version
Revised by Luis Ricardo Batallan
55222225
Prepared: MEX/TIM Luis Batallan
TEM/T-
Approved Ericsson: Subdirección de Calidad de Servicio y Evaluación del Desempeño de la Red
IMMEDIATE ASSIGNMENT REJECT
Approved TELCEL: Date: 2005-06-24
Rev. A
IMMEDIATE ASSIGNMENT REJECT Table of contents 1 2 3 4 5 6 UT
TU
TU
UT
TU
TU
UT
TU
UT
TU
UT
TU
UT
ABSTRACT PURPOSE OF THE DOCUMENT SCOPE INTRODUCTION TOLBS1 Analysis REFERENCES
TU
TU
UT
UT
TU
UT
TU
TU
UT
UT
UT
0 0 0 0 0 0
55333335 TEM/T-
Prepared: MEX/TIM Luis Batallan Approved Ericsson:
Subdirección de Calidad de Servicio y Evaluación del Desempeño de la Red
1
IMMEDIATE ASSIGNMENT REJECT
Approved TELCEL: Date: 2005-06-24
Rev. A
ABSTRACT U
On the analysis of Call Setup Failure has been found that for many BSC’s on Region 9 the Immediate Assignment Reject is a quite high (about 3%) and also a quite far from SDCCH congestion (about 0.5%) which would be the main reason for immediate assignment reject. This behavior trigger an in-deep analysis of the reason for immediate assignment rejects. 2
PURPOSE OF THE DOCUMENT U
The purpose of this document is to describe the problem found as reason for the increase of immediate assignment rejects. 3
SCOPE U
The TELCEL team involved on general Radio Network Optimization. 4
INTRODUCTION U
The immediate assignment reject is a message sent by the network to the MS mainly in the following situations: The IMMEDIATE ASSIGNMENT REJECT message is sent in the following situations: a) The random access is a request for 'Location Updating' or 'other procedures that can be completed with an SDCCH and NECI set to 1' and no channel available (default value for T3122=10 sec.) b) The Central Processor in BSC is overloaded (default value for T3122=20 sec.) c) Too many random accesses are received within 100 ms (more than 35 for APZ 212 11, more than 90 for APZ 212 25, more than 150 for APZ 212 20 and to be defined for APZ 212 30). (Default value for T3122=200 sec.)
Figure 1 – Immediate assignment reject
55444445 TEM/T-
Prepared: MEX/TIM Luis Batallan Approved Ericsson:
Subdirección de Calidad de Servicio y Evaluación del Desempeño de la Red
IMMEDIATE ASSIGNMENT REJECT
Approved TELCEL: Date: 2005-06-24
Rev. A
For the target BSC under study, TOLBS1, none of above situations was present and the SDCCH congestion was in average about 0.3% while the immediate assignment reject was about 3.5%. Therefore should exist another reason for the high percentage of immediate assignment reject. At this point personnel from Ericsson Local Support tracing failures at Call Setup find out that for Emergency Calls random access there is a software bug on the BSC that keeps the SDCCH resources “reserved” for emergency calls not allowing another users to access to SDCCH resources in the overlaid sub-cell even when there are SDCCH Idle in the sub-cell (overlaid) during 1 minute. The users can still accessing through SDCCH in the underlaid sub-cell, but in most of cells there is not SDCCH configured on the underlaid. The temporal solution is to add an SDCCH on underlaid sub-cell. The final solution is to load in the BSC a software correction that solves this bug or to change the release to BSS R11 where this problem has been solved. TOLBS1 ANALYSIS U
From the statistical analysis for TOLBS1 regarding immediate assignment reject and SDCCH congestion has been found that even when the SDCCH congestion attempts are not so high as the Immediate Assignment Reject.
REJCSIMMASS ⎛ ⎞ IMM _ ASS _ REJ = 100 * ⎜ ⎟[%] ⎝ REJCSIMMASS + CSIMMASS ⎠
TOLBS1 Immediate Assignment Reject vs SDCCH Attempt Congestion IMM ASS REJ
SDCCH ATT CONG
5 4.5 4 3.5 3 2.5 2 1.5 1 0.5 0 19/05/05 20/05/05 21/05/05 22/05/05 23/05/05 24/05/05 25/05/05 26/05/05 27/05/05 28/05/05 29/05/05 30/05/05 31/05/05 01/06/05 02/06/05 03/06/05 04/06/05 05/06/05 06/06/05 07/06/05 08/06/05 09/06/05 10/06/05 11/06/05 12/06/05 13/06/05 14/06/05 15/06/05 16/06/05 17/06/05 18/06/05 19/06/05 20/06/05
5
Figure 2 – Immediate assignment reject vs. SDCCH attempt congestion
55555555
Prepared: MEX/TIM Luis Batallan
TEM/T-
Approved Ericsson: Subdirección de Calidad de Servicio y Evaluación del Desempeño de la Red
Approved TELCEL:
IMMEDIATE ASSIGNMENT REJECT
Date: 2005-06-24
Rev. A
The increase on Immediate Assignment reject approximately at 22/05 is concurrent with the configuration of SDCCH on overlaid sub-cell. This is also consistent with the explanation from Ericsson support about the reason for the immediate assignment reject (Emergency calls issue as stated in chapter 4).
IMMEDIATE ASSIGNMENT REJECT CSIMMASS
IMM ASS REJ
354
1
0
0
0
0
0
0
0
55
33
162
10:00:00 p.m.
11:00:00 p.m.
12:00:00 a.m.
01:00:00 a.m.
02:00:00 a.m.
03:00:00 a.m.
04:00:00 a.m.
05:00:00 a.m.
06:00:00 a.m.
07:00:00 a.m.
08:00:00 a.m.
08:00:00 p.m.
09:00:00 p.m.
948
846
291
06:00:00 p.m.
07:00:00 p.m.
3045
628
05:00:00 p.m.
03:00:00 p.m.
04:00:00 p.m.
4072
2779
02:00:00 p.m.
16273
8439
10095
01:00:00 p.m.
12:00:00 p.m.
3771
2707
10:00:00 a.m.
11:00:00 a.m.
2744
09:00:00 a.m.
10.00% 9.00% 8.00% 7.00% 6.00%
08:00:00 a.m.
180000 170000 160000 150000 140000 130000 120000 110000 100000 90000 80000 70000 60000 50000 40000 30000 20000 10000 0
REJCSIMMASS
5.00% 4.00% 3.00% 2.00% 1.00% 0.00%
Figure 3 – TOLBS1 Immediate assignment reject (23/06 to 24/06 hourly)
After the configuration of one SDCCH in underlaid (23/06 5:00 PM) there is a clear decrease on the number of Immediate Assignment Reject as can be see on the figure above.
6
REFERENCES U
-
User description, Radio Network Statistics BSS R10 (216/1553-HSC 103 12 Uen A4)
-
User Guide, BSC Object Types and Counters Rev. F1 (3/198 17-APT 210 09 Uen)
-
Call Setup Failure (Luis Batallan, CS R9)
