Determining Call Processing Problems With Statistics

Determining Call Processing problems with Statistics AnalysisMotorola Internal

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1

Determining Call Processing Problems with Statistics

David ZhangCustomer Support

Presented on 20 Dec. 2004



2

Mobile Terminating/Originating Call Establishment

MS MTP/MSCRSS L1 RSS RRSM/RCI CRM/AM

BTS

SM SSM

BSC

Connection Request

Sccp_tconn_est

Initial Layer 3 messageCM service request Conn_req_to_msc

MS power control

Establish indication

CM service requestPaging Response

T3101 expires, peg

Chan_req_ms_failNo ok_acc_proc is pegged

Ok_acc_procms_access_by_type

SM SSM

BSC

access_per_rach

ok_acc_proc_suc_rach

Channel request

RACHChannel request

Channel requiredChan_req_cause_atmpt

INV_EST_CAUSE_ON_RACH

sdcch_congestion

Last SDCCH?Busy_SDCCH

channel required received

No SDCCH?ALLOC_SDCCH_FAIL

RSS ABIS

Immediate assignment reject

ALLOC_SDCCHChannel assigned

channel activation

channel activation acknowledge

Immediate assignment command T3101 is started to

Wait for “establishIndication”

Immediate assignment

AGCH

Access_per_AGCH

RSS L1


CHAN_REQ_MS_BLKD

AGCH

Layer 2

SABM on assigned SDCCH (max. 6)

UA on SDCCH channel

No UA if T3101 is expired

CM service request /Paging Response

Layer 3 Initial Message

Call Setup Flow Chart



3

Call Setup Flow Chart cont.1Mobile Terminating/Originating Call Establishment


BTS

SM SSM

BSC

MS power control Connection Request

Sccp_tconn_est


Connection Confirm

Conn_refusedDTAP Message DTAP MessageDTAP Message: Authentication requestDTAP MessageDTAP Message DTAP Message

Authentication Response DTAP Messageclassmark request

Request classmarkClassmark enquiryClassmark change update classmark Classmark update

Classmk_update_fail

DTAP: setup

DTAP: TMSI reallocation

DTAP: call proceeding

ciphering request cipher mode request

Ciphering_successfulCipher_comp_msCiphering mode command

Ciphering mode complete Ciphering successful Ciphering mode

completeCipher_comp_ms timeout

Ciphering_successfulexpires

Cipher_mode_fail

No ciphering Successful received

Establish indicationCM service requestPaging Response

T3101 expires, peg



clear requestClr_req_to_msc

RF_LOSSES_SDError IndicationRadio Channel Release

Link_fail declared

Connection Refused

Missing measurementreport




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Call Setup Flow Chart cont.2

Mobile Terminating/OriginatingCall Establishment

MS MTP/MSCRSSL1 RSS RRSM/RCI

CRM/AM

BTS

SM SSM

BSC

assignment requestma_req_from_mscAnd maybe:efr_req_from_mscOr:Ma_req_from_msc_fail

assign_successful

Initiate assignmentAssignment resource request

BSSMAP_T11Calls_queuedTch_q_length

Assignment channel assigned ALLOC_TCH

TCH_usageBusy_TCHTCH_congestion

Physical contextrequest

Physical context confirmed

channel activationchannel activation acknowledge

Total_calls

Ma_complete_to_mscNo assignment channelAssigned received, then

No queuing allowed or queue is full and all TCHs busy.

DR not in operation.resource not available

Ma_cmd_to_ms_blkdAlloc_tch_failUnsuccessful

assignment Assignment failure

Radio channel released

No queuing messageis sent to MSC whenDirect Retry is used

Force queue

Queuing indicationAssignment queued

Connection request

Switch response success

Assignment complete

BSSMAP_T10(T3107) expires

No assignment completereceived, then

BSSMAP_T10(T3107)Assignment failure

Assignment commandAssignment command

Assignment failureMa_fail_from_ms

Assignment complete


Assignment complete

Second_assign_atmpt

second_assign_suc

Assignment successful

FACCHSABM

UA MA_CMD_TO_MS

MA_COMPLETE_FROM_MS

MA_CMD_TO_MS



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Call Processing Problem Analysis

•RACH problem•RACH => SDCCH Problem•SDCCH Related Problem•SDCCH => TCH Problem•BTS related•BSC related Problem•MSC related



6

Backward Check: A Quick Way to Find Problem

•MA_REQ_FROM_MSC = TOTAL_CALLS Not SDCCH => TCH Problem•MA_COMPLETE_FROM_MS = TOTAL_CALLS NO BTS-BSC or BSC SM related Issue•MA_CMD_TO_MS = TOTAL_CALLS NO MS related problem if MA_FAIL_FROM_MS = 0•MA_REQ_FROM_MSC > MA_CMD_TO_MS TCH Queuing or blocking related problem => Check Known Issue Clarify etc =>CS web page => CP development web page



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SDCCH => TCH Problem ?

Mobile Terminating/OriginatingCall Establishment

MS MTP/MSCRSSL1 RSS RRSM/RCI

CRM/AM

BTS

SM SSM

BSC

assignment requestma_req_from_mscAnd maybe:efr_req_from_mscOr:Ma_req_from_msc_fail

assign_successful

Initiate assignmentAssignment resource request

BSSMAP_T11Calls_queuedTch_q_length

Assignment channel assigned ALLOC_TCH

TCH_usageBusy_TCHTCH_congestion

Physical contextrequest

Physical context confirmed

channel activationchannel activation acknowledge

Total_calls

Ma_complete_to_mscNo assignment channelAssigned received, then

No queuing allowed or queue is full and all TCHs busy.

DR not in operation.resource not available

Ma_cmd_to_ms_blkdAlloc_tch_failUnsuccessful

assignment Assignment failure

Radio channel released

No queuing messageis sent to MSC whenDirect Retry is used

Force queue

Queuing indicationAssignment queued

Connection request

Switch response success

Assignment complete

BSSMAP_T10(T3107) expires

No assignment completereceived, then

BSSMAP_T10(T3107)Assignment failure


Assignment failureMa_fail_from_ms

Assignment complete


Assignment complete

Second_assign_atmpt

second_assign_suc

Assignment successful

FACCHSABM

UA MA_CMD_TO_MS

MA_COMPLETE_FROM_MS

MA_CMD_TO_MS



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Example 1: MA_CMD_TO_MS_BLKD With Free TCH

ext_range_cell = 0 max_q_length_full_rate_channel = 0queue_management_information = 0poor_initial_assignment = 0 SR1026400 & SR1096357

MA_FAIL_FROM_MS SECOND_ASSIGN_ATMPTSECOND_ASSIGN_SUCCESS ALLOC_TCH_FAIL MA_CMD_TO_MS_BLKD AVAILABLE_TCH_MAX MAX_TCH_BUSY13 13 12 1 1 19 1117 15 13 0 0 19 119 9 8 1 1 19 9

TCH_Q_REMOVED CALLS_QUEUED TCH_CONGESTION0 0 00 0 00 0 0

MA_FAIL_FROM_MS =SECOND_ASSIGN_ATMPT = SECOND_ASSIGN_SUCCESS + MA_CMD_TO_MS_BLKD



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Example 1_1: MA_CMD_TO_MS_BLKD with Free TCH

iir_mod 32 21000000hiir_mod 34 1111301hHder: df 7 di 47c8 dm 4 tag 1000034a(CP_INT MT_RF_RES_IND_RCVD)Mlen 21(deci): 4a f0 47 f1 2 15 e b 20 d 20 9 20 a 20 f 20 c 20 e 20 crm: crv_rf_res_ind_rcvd.c: Statistic IDLE_TCH_INTF_BAND0 updated: 10 in cell: 47h# This indicates that there are 10 TCHs available in interference band 0 for this cell…Hder: df 7 di 4792 dm ab tag 8000349(CP_INT MT_CHAN_REQUIRED_RCVD)channel_required.c: Statistic CHAN_REQ_CAUSE_ATMPT(cause: 4h) incremented for cell: 47hMlen 15(deci): 49 f0 47 f1 2 1 90 13 9c 13 98 11 3f ff 0 …



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Example 1_2: MA_CMD_TO_MS_BLKD with Free TCH

Hder: df 7 di 4790 dm 4 tag 10031e(CP_INT MT_ASSIGN_RES_REQ)Mlen 39(deci): 1e f3 47 3 80 f0 47 f1 5 18 3f b 4 1 8 91 1 0 0 0 0 7 3 23 18 1 0 0 ff 0 0 0 6 1 2a ff 0 ff 0…



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Example 1_3: MA_CMD_TO_MS_BLKD with Free TCH…crm: f_update_alloc_stats.c: Statistic ALLOC_TCH incremented for cell: 47h…rrsm:build_data_req_assign_cmd.c: Statistic MA_CMD_TO_MS incremented for cell: 47hrrsm:rrsm_stats.c: Statistic MA_FAIL_FROM_MS incremented for cell: 47h# The MS failed to access the referred TCH.rrsm_trans_101.c: Statistic SECOND_ASSIGN_ATMPT incremented for cell: 47hHder: df 7 di 4708 dm 4 tag 100387(CP_INT MT_SUBSEQ_ASSIGN_RES_REQ)Mlen 28(deci): 87 f3 47 3 80 f0 47 b 3 1 8 11 14 1f 21 5 1 0 ff 0 0 18 40 7 3 23 18 1crm: f_update_alloc_stats.c: Statistic ALLOC_TCH_FAIL incremented for cell: 47hrrsm:rrsm_stats.c: Statistic MA_CMD_TO_MS_BLKD incremented for cell: 47h



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Example 2: MA_CMD_TO_MS_BLKD with free TCH

max_q_length_full_rate_channel = 4queue_management_information = 4Bssmap_t11 = 20000 > TCH_DELAY_MAXSR1079168

DEVICE DATE TIME ASSGN_RES_REQ TCH_Q_LENGTH_MAX CALLS_QUEUED TCH_Q_REMOVED24_SHOUBRA_EL_BALAD_S444 24-08-2003 00:00 0 0 0 0

11:30 1 1 1 112:00 22 2 22 2212:30 17 1 17 17

TCH_Q_LENGTH_MAX MA_CMD_TO_MS_BLKD TCH_CONGESTION TCH_DELAY_MAX(milliseconds) AVAILABLE_TCH_MAX BUSY_TCH_MAX0 0 0 0 12 111 1 6290 110 12 122 11 49635 2985 12 121 7 46650 355 12 12

ASSGN_RES_REQ = MA_CMD_TO_MS_BLKD = CALLS_QUEUED



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Example 2_1: MA_CMD_TO_MS_BLKD with free TCH

max_q_length_full_rate_channel = 4queue_management_information = 4max_q_length_sdcch = 0protect_last_ts = 1Bssmap_t11 = 20000

MCU:emon_1015 % msg_send 34 9000h 0 0 0 0b2h 0f0h 13h …Number of queued reqs: SDCCH=000, TCH/F=000, Emerg TCH/F=000. Res Ind: Timer Val=0000, Timer ID=00000000, Method=03, Total Access=00. Counters: Emerg Pending for Prim MS=00, EGSM MS=00 Queued Total=00000, Int=00020.

…Hder: df 7 di 130c dm 4 tag 10031e(CP_INT MT_ASSIGN_RES_REQ)Mlen 39(deci): 1e f3 13 6b 60 f0 13 f1 6 18 1 b 4 1 8 91 1 0 0 0 0 7 3 23 19 81 0 0 ff 0 0 0 6 1 12 ff 0 ff 0 crm: f_update_alloc_stats.c: Statistic ALLOC_TCH_FAIL incremented for cell: 13hrrsm:rrsm_stats.c: Statistic MA_CMD_TO_MS_BLKD incremented for cell: 13h

# Why the call wasn’t queued ?



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Example 3_0: MA_CMD_TO_MS_BLKD & Queue Timeout

avail_tch_max busy_tch_max tch_congestion calls_queued alloc_tch_fail ma_cmd_to_ms_blkd

9 3 0 9 9 9

9 5 0 2 2 2

9 5 0 2 2 2

9 4 0 4 4 4

ma_fail_from_ms Second_Assign_Atmpt Second_Assign_Succ clr_req_to_msc Congest_Assign_HO_Suc Congest_Exist_HO_AtmptCongest_Stand_HO_Atmpt

0 12 1 0

0 6 0 0

1 2 2 0

0 6 0 0

max_q_length_full_rate_channel = 0queue_management_information = 0second_asgnmnt = 1



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Example 3_1: MA_CMD_TO_MS_BLKD & Queue Timeoutqueue_management_information = 0max_q_length_full_rate_channel = 0max_q_length_sdcch = 0poor_initial_assignment = 0 at BTSext_range_cell = 0second_asgnmnt = 1 at BSCHder: df 7 di 5f54 dm c3 tag 8000349(CP_INT MT_CHAN_REQUIRED_RCVD)Mlen 15(deci): 49 f0 5f f1 6 1 90 13 81 4b ed 11 43 ff 0 # Look at the decode the TA is 66 Hder: df 7 di 5f0c dm 4 tag 10031e(CP_INT MT_ASSIGN_RES_REQ)Mlen 39(deci): 1e f3 5f 15 20 f0 5f f1 7 18 43 b 4 1 8 91 1 0 0 0 7 5 33 19 81 60 14 ff 0 0 0 6 1 38 ff 0 ff 0 # TA is same as before which is 66 (43h) (count to number 11th)crm: f_update_alloc_stats.c: Statistic ALLOC_TCH_FAIL incremented for cell: 5fhcrm: f_queue_request.c: Statistic TCH_Q_LENGTH updated for cell: 5fh Current queue length: 1crm:crv_assign_res_req.c: Statistic CALLS_QUEUED incremented for cell: 5fh# Since we don’t have extended range cell TCH so the call is moved to queue# Also we don’t have MA_CMD_TO_MS then MA_FAIL_FROM_MS so Second assignment# doesn’t start, bssmap_t11 startedrrsm: rrsm_trans_016.c: Statistic MA_CMD_TO_MS_BLKD incremented for cell: 5fhHder: df 7 di 5f29 dm 4 tag 10031f(CP_INT MT_REMOVE_FROM_QUEUE_TO_CRM)Mlen 9(deci): 1f f3 5f 15 20 b 1 ff 14 crm: crv_rm_from_queue.c: Statistic TCH_Q_LENGTH updated for cell: 5fh, Current queue length = 0h# bssmap_t11 timeout caused MA_CMD_TO_MS_BLKD pegging

SR1110086 & SR1096357/MOTCM00256635



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On SDCCH: SDCCH Related problemMobile Terminating/Originating Call Establishment


BTS

SM SSM

BSC

MS power control Connection Request

Sccp_tconn_est


Connection Confirm

Conn_refusedDTAP Message DTAP MessageDTAP Message: Authentication requestDTAP MessageDTAP Message DTAP Message

Authentication Response DTAP Messageclassmark request

Request classmarkClassmark enquiryClassmark change update classmark Classmark update

Classmk_update_fail

DTAP: setup

DTAP: TMSI reallocation

DTAP: call proceeding

ciphering request cipher mode request

Ciphering_successfulCipher_comp_msCiphering mode command

Ciphering mode complete Ciphering successful Ciphering mode

completeCipher_comp_ms timeout

Ciphering_successfulexpires

Cipher_mode_fail

No ciphering Successful received

Establish indicationCM service requestPaging Response

T3101 expires, peg



clear requestClr_req_to_msc

RF_LOSSES_SDError IndicationRadio Channel Release

Link_fail declared

Connection Refused





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SDCCH Related Problem

• Here is Our stats’s weak point We assume that every conn_req is replied by MSC

• No MSC related problem

conn_refused = 0

conn_refused = IMSI_DETACH

If it is NOT, MSC has problem!



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Example 4: SDCCH_HO related issue

Hour CI alloc_tch_fail alloc_sdcch_fail HO_Fail_No_Resources

15:00:00 6915 0 0 0

16:00:00 6915 0 9 0

17:00:00 6915 4 489 4

18:00:00 6915 3 1580 3

19:00:00 6915 2 575 2

20:00:00 6915 2 94 2

21:00:00 6915 0 2 0

No TCH congestion & sdcch_ho = 1



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Example 4_1: SDCCH_HO related issueHder: df 7 di 2e08 dm 5 tag 400311(CP_INT MT_INTERN_HANDO_REQ)Mlen 81(deci): 11 f3 28 69 0 f0 28 c4 c 23 0 2b 0 b 3 3 1 0 0 0 0 0 0 a 9 2 51 97 dc f4 b3 c0 f0 0 0 0 0 0 0 0 0 0 0 7 1 23 0 0 0 0 2 0 5a 3 5 6 1 38 ff 0 0 ff 0 ff 0 ff 0 0 0 0 0 0 0 0 0 ff 0 ff 0 ff 0



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Example 4_2: SDCCH_HO related issueChannel Type M 7,11 5 – 10 GSM 08.08 5.1.11 b 3 3 1 0 0 0 0 0 0 b - IEI3 – LENGTH3 - Signalling The speech or data indicator field is coded as follows:0001 Speech0010 Data0011 SignallingAll other values are reserved.1 – SDCCH0 0 0 0 0 0 - filling bytes



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Example 4_3: SDCCH_HO related issue

crm: f_update_alloc_stats.c: Statistic ALLOC_TCH_FAIL incremented for cell: 2eh

crm:crv_int_ho_req.c: Statistic HO_FAIL_NO_RESOURCES bin: 0h incremented for cell: 2eh …crm: f_calculate_ho_power.c : HO Power Level: (In dBm) : TxMs :Gamma :PwrMs : NCell : Box : Ord : OrdPL : DBoffLCI : 46 : 33 : 25 : 33 : -71 : -49 : -3 : 19 : 0Hder: df 7 di 2d1a dm 5 tag 400311(CP_INT MT_INTERN_HANDO_REQ)Mlen 81(deci): 11 f3 13 43 41 f0 13 c4 c 23 0 2b 0 b 3 3 1 0 0 0 0 0 0 a 9 2 f9 a6 a2 e7 cf eb c 0 0 0 0 0 0 0 0 0 0 7 533 58 81 60 14 2 0 5c 3 7 6 1 38 ff 0 0 ff 0 ff 0 ff 0 0 0 0 0 0 0 0 0 ff 0 ff 0 ff 0 # Another SDCCH Handovercrm: f_set_ms_freq_band.c: ms_freq_band(11h),cell_id(2dh),freq_band(0h), rev_level(1h), egsm_bit(ffh)crm: f_update_alloc_stats.c: Statistic ALLOC_TCH incremented for cell: 2dh

SR1072540/PR176091



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RACH => SDCCHMobile Terminating/Originating Call Establishment


BTS

SM SSM

BSC

Connection Request

Sccp_tconn_est


MS power control

Establish indication

CM service requestPaging Response

T3101 expires, peg



SM SSM

BSC

access_per_rach

ok_acc_proc_suc_rach

Channel request

RACHChannel request

Channel requiredChan_req_cause_atmpt

INV_EST_CAUSE_ON_RACH

sdcch_congestion

Last SDCCH?Busy_SDCCH

channel required received

No SDCCH?ALLOC_SDCCH_FAIL

RSS ABIS


ALLOC_SDCCHChannel assigned

channel activation

channel activation acknowledge

Immediate assignment command T3101 is started to

Wait for “establishIndication”

Immediate assignment

AGCH

Access_per_AGCH

RSS L1


CHAN_REQ_MS_BLKD

AGCH

Layer 2

SABM on assigned SDCCH (max. 6)

UA on SDCCH channel

No UA if T3101 is expired

CM service request /Paging Response

Layer 3 Initial Message



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Identify the problem on RACH => SDCCH

•No BTS-BSC problem OK_ACC_PROC = CONN_REQ_TO_MSC

•ACCESS_PER_AGCH = OK_ACC_PROC + CHAN_REQ_MS_FAIL

•ALLOC_SDCCH = ACCESS_PER_AGCH

•CHAN_REQ_MS_BLKD = ALLOC_SDCCH_FAIL

•CHAN_REQ_CAUSE_ATMPT = ALLOC_SDCCH_FAIL + ALLOC_SDCCH



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Example_5 – SR1074144/1074543/1072103

bssname sitename Expr1002 dt cellname cm_serv_req_call cm_serv_req_emerg cm_serv_req_sms page_response sms_init_on_sdcch total_calls

B16-Elvsborg Skarsjon-G-288 288C 01-Jul-03 288C 0 0 0 0 0 32







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Summary

• very useful to find call processing problems if you are familiar with Statistics pegging

• Backward statistics check is a very good way to narrow down the function area very quickly

http://www.ecid.cig.mot.com/~q13170/GSM/callsetup/call_setup.html

Determining Call Processing Problems With Statistics

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