traning for process & core optimizaton part 1

8/2/2019 Traning for Process & Core Optimizaton Part 1

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2 © Nokia Siemens Networks /

KPI Evaluation Process



3 © Nokia Siemens Networks

HOW DO WE NEED TO START OPTIMIZATION

• Firstly we need to check the KPI of Cluster Level & BSC level

• After that Check the KPI of which BSC is going down and then find thecells due to which KPI’s going worst

• Now check the Cells KPI ( Preferably CSSR, DCR & HOSR ) why it is goingworst

• If CSSR KPI is worst then we need to check all the components of theCSSR ( TCH Blocking, SDCCH Blocking, SDCCH Drop, TCH Assignmentsuccess Rate) & if DCR KPI worst check all the Raw counters alsoaccording to the formula and same procedures for the HOSR.

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We need no check all the countersalso for the respective KPI’s not justlike high Blocking or high Drops as itis also plays the very important rolein Core-optimization




CSSR KPI

• As we know CSSR depends on the 4 Components ( TCH Blocking,SDCCH Blocking, SDCCH Drop, TCH Assignment success Rate )and if any of the components KPI’s going worst than CSSR will be theworst.

• I will discuss these cases one by one

• For Hardware we will discuss later

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CASE-1 CSSR BAD Due To High SDCCH Drop Rate

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As the above KPI shows that CSSR is going

worst due to high SDCCH Drop Rate and No wehave to find out the reason for High SDCCHDrop Rate

SDCCH Drop rate may behigh due to many reasonsas given below

Hardware Problem in aCellOvershootingCo-channel Interference

Transmission issuePhantom RACHExtra SDCCH




SDCCH requests

SDCCH REQUESTS

/c 1000

sdcch_seiz_att

ASSIGNMENTSFOR CALLS,LU,SS

/c 1007

sdcch_assign

BLOCKED

/blck_15

sdcch_busy_att -tch_seiz_due_sdcch_con

RACH on CCCH

/c 3004

ch_req_msg_rec

REJECTED DUE

TO ILLEGALEST.CAUSE

/c 3030

ghost_ccch_res

5/8 OF GHOSTS (ph.1) ANDOTHER FAILURESBEFORE ESTABL.INDICATION

(incl.IMSI detach):

/SD_1a

c1007- TRF_25

MOC (incl.SMS)

/c 3013

succ_seiz_orig

MTC (incl.SMS)

/c 3012

succ_seiz_term

CALL RE-EST.

/c 3020

sdcch_call_re_est

LOCATION UPDATE

/c 3019

sdcch_loc_upd

EMERGENCY CALL

/c 3021

sdcch_emerg_call

SDCCH ACCESSES REJECTED IN BSC

TRUE SDCCH SEIZURES

/ TRF_25a (not updated in SDCCH HO)

SEIZURES FOR HO

/c 1006

sdcch_ho_seiz

SDCCH FAILURES

/c 1075sdcch_abis_fail_call

(blocked chan.,corrupted

msgs, failed chan.act.)

TRUE SDCCH SEIZURES FOR CALL,SMS,SS

/ TRF-27

IMSI DETACH

/c 3033 (S7)

imsi_detach_sdcch

TRUE SDCCH SEIZURES

FOR CALL & SS

/ TRF-26

TRF-27

- succ_sdcch_sms_est

- unsucc _sdcch_sms_est

TRUE SDCCH SEIZURES

FOR SMS

succ_sdcch_sms_est

+ unsucc _sdcch_sms_est

SDCCH BLOCKING ( blck_5a )

SDCCH-

SDCCH HO

other than

sdcch_abis_* failures

small part of failures

Normal LU

Periodic LU

IMSI attach

MS accessing,

noise (ghosts)

NOTE:

Triggered also in case of

HO attempt if there are no

free SDCCH

SDCCH-

SDCCH

HO

TCH

FACCH call setups

/c 1099

tch_seiz_due_sdcch_con

Distance checking

BSS5280 (S5)

3/8 of ghosts (ph.1)

REJECTED DUE TODISTANCE

/c 3031 (S5)

rej_seiz_att_due_dist

SDCCH FAILURES

/c 57020 (S7)

t3101_expired

(Ghosts)

CALL RE-EST. ASSGN.

/c 57022 (S7)

sdcch_re_est_assign

Supplementary servicerequest (S9)

/c 3044

T3101 adjustable by MMLZEGT:T3101..

http://nea.ntc.nokia.com/cgi-bin/cgiwrap/neva/counters?001000




http://nea.ntc.nokia.com/cgi-bin/cgiwrap/neva/frmls?sd_1a






http://nea.ntc.nokia.com/cgi-bin/cgiwrap/neva/frmls?trf_25a



http://nea.ntc.nokia.com/cgi-bin/cgiwrap/neva/frmls?trf_27





http://nea.ntc.nokia.com/cgi-bin/cgiwrap/neva/frmls?blck_5a






http://essrv509ntc.ntc.nokia.com:6336/dynaweb/NED31_bsc_s8e/9090313/@Generic__BookView;pt=27101?DwebQuery=t3101

http://essrv509ntc.ntc.nokia.com:6336/dynaweb/NED31_bsc_s8e/9090313/@Generic__BookView;pt=27101?DwebQuery=t3101






http://nea.ntc.nokia.com/cgi-bin/cgiwrap/neva/frmls?blck_5a







http://nea.ntc.nokia.com/cgi-bin/cgiwrap/neva/frmls?trf_25a






http://nea.ntc.nokia.com/cgi-bin/cgiwrap/neva/frmls?sd_1a






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SDCCH Drop Rate KPI Analysis

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Please make sure SDCCH_ABIS_FAIL_CALL counter we don’t

include in the KPI’s formula of SDCCH Drop Rate as this is notthe customer satisfactory .

Now in the above KPI we can see the SDCCH drop rate is high due toSDCCH A interface fail call is high as major drops are going only on thiscounter and it is suspected due to Transmission issue so for root causewe need to check the all counters.



SDCCH Drop Rate Analysis Based on Several Reasons

• If SDCCH_Radio_fail counter value is high it means drops going may bedue to Overshooting, interference , Phantom RACH etc.

• If 7745 Channel Failure Rate Alarm persist on SDCCH then Shift theSDCCH from that TRX to another TRX.

• For Extra SDCCH we need to check the SD Configuration as per Nokiasystem 1 SDCCH can take 5000 SDCCH attempts , for this don’t consider the daily KPI, please see the next slide for better explanation of this

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Extra SDCCH Analysis

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According to KPI there should be only one

SDCCH timeslot but if I check the Databaseconfiguration it has 4 SDCCH so we need toremove the extra SDCCH from the TRX’s



CASE-2 CSSR BAD DUE TO BAD TASR

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TASR Bad due to Several ReasonsHardware Faulty

Timer T10 Expired ( BSC Level)Queuing not Allowed

Queue FullDue to Radio ProblemDue to Hardware Issue



TASR FORMULA

• [sum(a. tch_radio_fail + a. tch_abis_fail_call + a. tch_a_if_fail_call + a. tch_tr_fail + a.

tch_user_act + a. tch_bcsu_reset + a. tch_netw_act + a. tch_act_fail_call + a. tch_lapd_fail + a.tch_bts_fail )]• - [sum(a. spare057044 ) - sum(a. tch_rf_old_ho + a. tch_abis_fail_old + a. tch_a_if_fail_old + a.

tch_tr_fail_old )]• 100%( * ----------------------------------------------------------------------------------------------------) %• sum(a .tch_norm_seiz ) ;

(normal calls)• + sum(c .msc_i_sdcch_tch + c. bsc_i_sdcch_tch + c. cell_sdcch_tch )

;(DR calls)• - sum(a. tch_succ_seiz_for_dir_acc ) ;ref.2• + sum(a. tch_seiz_due_sdcch_con ) ;(FACCH call

setup• • • Counters from table(s):• a = p_nbsc_traffic• c = p_nbsc_ho

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Number of successful incoming SDCCHto TCH HOs controlled by the MSC




What is TCH Blocking ?

BUSY BUSY BUSY BUSY BUSY BUSY BUSY BUSY

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All Timeslots are busy

When all timeslots ( 8 TS) are busy then it is called congestionand when at the time of congestion any call come through thatbusy timeslot then it is called blocking.




• Formula:

• 100 * [sum(a.tch_call_req - a.tch_norm_seiz) - sum(b.msc_o_sdcch_tch +b.bsc_o_sdcch_tch + b.cell_sdcch_tch) + sum(a.tch_succ_seiz_for_dir_acc) –sum {a.tch_rej_due_req_ch_a_if_crc -(b.bsc_i_unsucc_a_int_circ_type + b.msc_controlled_in_ho + b.ho_unsucc_a_int_circ_type) } ]

• ______________________________________________________ • [sum(a.tch_call_req) – sum {a.tch_rej_due_req_ch_a_if_crc -

(b.bsc_i_unsucc_a_int_circ_type + b.msc_controlled_in_ho +b.ho_unsucc_a_int_circ_type) } ]

TCH Blocking Formula (%)




• Formula: (Nom)

• 100 * [sum(a.tch_call_req - a.tch_norm_seiz) –• sum(b.msc_o_sdcch_tch + b.bsc_o_sdcch_tch + b.cell_sdcch_tch) +

sum(a.tch_succ_seiz_for_dir_acc) –

• sum {a.tch_rej_due_req_ch_a_if_crc -(b.bsc_i_unsucc_a_int_circ_type + b.msc_controlled_in_ho + b.ho_unsucc_a_int_circ_type) } ]

TCH Blocking (%)No. of TCH requests

for normalassignment. (1026)

No. of successful TCHrequests for a normalassignment. (1009)

No. successful SD-TCHHO. (4050)

No. successful SD-TCH HO. (BSC

Controlled) (4065)

No. successful SD-TCH HO. (Intra-cell)

(4074)

Number of successful TCHseizures in direct accesses to a

super-reuse TRX during thecall set-up phase. (1165)

Number of rejected TCHrequests due to mismatchbetween the requested channeltype and the A-interface circuittype (1122)

Number of unsuccessfulhandovers due to wrong A-interface circuit type. (4097)

Number of unsuccessfulhandover due to wrong A-interface circuit type. (4098 )

Number of unsuccessfulhandovers due to wrong A-interface circuit type. (4101 )




• Formula: (Denom)

• sum(a.tch_call_req) – sum {a.tch_rej_due_req_ch_a_if_crc -(b.bsc_i_unsucc_a_int_circ_type + b.msc_controlled_in_ho +b.ho_unsucc_a_int_circ_type) }

TCH Blocking (%)No. of TCH requests

for normalassignment. (1026)

Number of rejected TCHrequests due to mismatchbetween the requested channeltype and the A-interface circuittype (1122)

Number of unsuccessfulhandovers due to wrong A-interface circuit type. (4097)

Number of unsuccessfulhandovers due to wrong A-interface circuit type. (4101 )

Number of unsuccessfulhandover due to wrong A-interface circuit type. (4098 )




• Formula:

• 100 * (traffic.sdcch_busy_att - traffic.tch_seiz_due_sdcch_con)/traffic.sdcch_seiz_att

• Counter from table: p_nbsc_traffic (Traffic Measurements)

SDCCH Blocking (%)Unsuccessful SDCCH seizure

attempts, due to non-availability of SDCCH (1001)

Successful seizures of TCH due to SDCCHcongestion (1099)

Total no. of SDCCH

seizure attempt (1000)




TCH Blocking Reasons

• Hardware Problem ( May be TRX faulty or any other hardware issue)

• Overshooting ( due to this cell are taking calls from very large distances)

• Any event ( Match, Exhibition, Meeting etc)

• Handover is better Cell is not occurring

• High rate of assignment failure messages

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Optimization TCH BlockingIf hardware problem exist then need to escalate to the concerned personIncrease dual Rate for reduce the TCH Blocking ( TCHF TCHD,

TCHH TCHD)Check FRL & FRU setting ( BTS Level)Check HRL & HRU setting ( BSC Level)Check HRI ( TCH in handover) setting ( BSC Level) ( it should be 5 and it meansTCH has to be primarily allocated from the best BTS of the handover candidatelist)

Directed Retry EnableRemove Extra SDCCH Channel and convert in to TCHD in case of high TCHTraffic to reduce the blockingIn case of Overshooting check RXP settingIn case of very high traffic in clusters then we can reduce the power

Traffic Sharing• Add Extra TRX• Add New Site• Optimize the cell boundaries to share the traffic with surrounding cells• Traffic Reason Handover enable

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SDCCH BLOCKING REASONS

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Too much SDCCH “normal” traffic for cell SDCCH design

- Logical cell design, extra TRX, new site

LA border at crowded area ( Check HYS Setting)

Abnormal SDCCH traffic- “phantom” channel requests- Inadequate LAC design, causing too much LU- Redesign LAC- Problem with neighbor cells belong to other LAC




SDCCH BLOCKING ANALYSIS

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Channel Failure Rate Above Defined Threshold

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Please see the given below core analysis for the 7745 Alarm

02 01 01 00 00 00 00 00 00 01 04 100d

02 represents Alarm onSDCCH Channel 8 Time Slots

01 means Faulty Timeslot

time slot with the highestfailure rate

Shift the SDCCH channel from that TRX or remove SDCCH if there is extra SDCCH timeslotsThe same scenario start for TCH but at the starts there is 01 in place of 02 and for that is any timeslot is faulty then we cango for Locking Timeslot & Locking TRX and after Lock we can check the Performance in Hourly KPI




SCCP Disturbance

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0B 08 0000188D FE 0000177B FE 0000

0B means Sending Message to MTP has Failed08 Means National Network 0




SDCCH Drop Rate Affects By Transmission Alarm

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k k

THANKS

traning for process & core optimizaton part 1

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