7745 Alarm Troubleshoot

7745 – Alarm TRX CHANNEL FAILURE RATE ABOVE DEFINED THRESHOLD

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7745 - CHANNEL FAILURE RATE ABOVE DEFINED THRESHOLD Meaning The rate of calls terminating in failure on a channel is above the threshold value set by the operator. The alarm is used to supervise the functioning of traffic and signaling channels, and to detect the possible faulty channels. Alarm in TRXlevel, reported in BSC Category Quality of Services Alarm, Severity Medium

KeyWord Whenever a channel is released with a release cause other than a normal one, the counter of channel failures for the released channel is incremented. NSN Default Threshold : TCHFR = TCH failure rate (20 % or 30%) SCHFR = SDCCH failure rate (80 %) PRDCFR = length of supervision period (60 min) CS = channel seizure threshold value (10) 2


7745 - CHANNEL FAILURE RATE ABOVE DEFINED THRESHOLD Channel Release procedure

Whenever a channel is released with a release cause other than a normal one, the counter of channel failures for the released channel is incremented. After a certain observation time and a certain threshold it will reported in the 7745 alarm. It give an indication that there’s a failure that need to be addressed, but overall KPI need to be used as a first priority. 3


7745 - CHANNEL FAILURE RATE ABOVE DEFINED THRESHOLD 7745 alarm occurance in Telkomsel Network Around 90% is affected in TCH, around 10% is affected in SDCCH Abnormal relase cause defined below : TCH Failure 0A Channel state conflict between RRMPRB and ABIPRB 0B Channel type conflict between RRMPRB and ABIPRB 0D TCH radio failure 0E Source TCH radio failure in HO 0F Target TCH radio failure in HO 1D TCH transcoder failure 1E Source TCH transcoder failure in HO 1F Target TCH transcoder failure in HO 2E TCH failure due to a LAPD failure 2F TCH failure due to a BTS failure 30 TCH failure due to user actions 31 TCH failure due to a BCSU reset 32 TCH failure due to radio network reconfiguration actions 51 TCH activation failure during call set-up 53 Target TCH activation failure in HO 54 TCH failure due to an Abis interface failure in call set-up 55 Source TCH failure due to an Abis interface failure in HO 56 Target TCH failure due to an Abis interface failure in HO 57 TCH failure due to an A interface failure in call set-up 58 Source TCH failure due to an A interface failure in HO 59 Target TCH failure due to an A interface failure in HO FF Actually no release cause, but causes all channels with an abnormal release cause to be listed 4


SDCCH Failure 03 SDCCH radio failure 04 Source SDCCH radio failure in HO 05 Target SDCCH radio failure in HO 0A Channel state conflict between RRMPRB and ABIPRB 0B Channel type conflict between RRMPRB and ABIPRB 23 SDCCH failure due to a LAPD failure 24 SDCCH failure due to a BTS failure 25 SDCCH failure due to user actions 26 SDCCH failure due to a BCSU reset 27 SDCCH failure due to radio network reconfiguration actions 48 SDCCH activation failure during call set-up 4A Target SDCCH activation failure in HO 4B SDCCH failure due to an Abis interface failure in call set-up 4C Source SDCCH failure due to an Abis interface failure in HO 4D Target SDCCH failure due to an Abis interface failure in HO 4E SDCCH failure due to an A interface failure in call set-up 4F Source SDCCH failure due to an A interface failure in HO 50 Target SDCCH failure due to an A interface failure in HO

7745 - Alarm Information AKSES_UI BCF-0065 BTS-0156 QUAL 2009-01-13 13:51:49.59 ** ALARM TRX -006 JNCSILIWANGIMD2 DISABLED (60756) 7745 CHANNEL FAILURE RATE ABOVE DEFINED THRESHOLD 01 00 01 01 01 01 01 00 00 04 00 48d AKSES_UI BCF-0065 BTS-0156 QUAL 2009-01-13 13:51:49.59 .. CANCEL TRX -007 JNCSILIWANGIMD2 ENABLED (60755) 7745 CHANNEL FAILURE RATE ABOVE DEFINED THRESHOLD 01 00 00 00 00 00 00 00 00 00 00 0d

Supplementary information fields 1 indicates if the alarm is on the TCH or on the SDCCH channel 01: TCH 02: SDCCH 2..9 indicates if the channel failure rate is above the defined threshold in time slot 0 00: belove threshold (no alarm) 01: above threshold (alarm) 10 time slot with the highest failure rate 11 subchannel identification TCH: 00: TCH/H -subchannel 0 01: TCH/H -subchannel 1 02: TCH/F -subchannel subchannel identification SDCCH: 00 - 07: SDCCH -subchannel 0 – 7 12 proportion/percentage of TCH or SDCCH subchannel releases due to failure in all channel releases on a given channel during the measurement period 5


Tools or verification that have been performed so far by NSN before/during site visit • Basic SW for Monitoring NE MML, BTS Manager

• KPI Browser Cell Doctor (report 211 Network Doctor) OSS Cell KPI (report 204 Network Doctor) OSS

• Basic verification of site condition – for new sites VSWR test verification (VSWR, RL, DTF verification) Verification of Main and Diversity receive level TRX Test function from BTS manager

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Step By Step - Flowchart for investigation methodology Start 7745

Root Cause & Suplementary information

ND 196 > uplink & downlink Quality ND 195 > TRX by downlink /uplink level balance ND 232 > Time advance ND 153 > Handover

Coordinate with OSS

SD & TCH

TCH : 59, 0F, 0D SDCCH : 4B, 4D

Audit Neighbours

Check TSC TRX using ZERO command BCC using ZEQO command

Switch BCCH Frequency to another TRX

Site Visit

Action

ND 195 : Unbalanced Uplink & downlink per TRX ND 196 : Uplink/Downlink Quality

ND 232 : Time Advanced (from drive test)

Retune, Check Parameter ARFCN or Audit Antenna tilting

Change Request & Execute

1. Check VSWR / cross feeder, Check Antenna/feeder/arrester/grounding. 2. Check cable connection & Hardware inspection, swap existing module 3. Hardware replacement if needed. i.e : TRX, DVXX, BB2X, etc

KPI OK Alarm

Y

End

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N

Investigation together with PLO

BTS installation standard

TX1,2 and RX main

TX 3 , 4 and RX div

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If we have 7745, 7743 alarms in our network, what is really happening? Before Site Visit : Make sure Audit neighbor, TSC checking and TRXtest

Action on site : 1.

2.

3.

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7745, 7743 at one TRX only - Check SMA cable at Tx connector to WCXA of the TRX, make sure properly connected - Replace TRX, BB2F and SMA cables if needed 7745, 7743 at two TRX - Try to switch BCCH, if still appear potential have a partial cross feeder - Replace TRX, BB2F WCXA, or DVXA if needed - Check alarms of other sector to ensure analysis 7745, 7743 at all TRXs under same cell - Possibilities error : full partial cross feeder, bad feeder quality and its connection, interference, broken DVXA


If we have 7745, 7604 alarms in our network, what is really happening? If: VSWR have been checked, Then: We can find out from hardware by checking its transmit path from TRx unit, Tx port, SMA-cables from Tx port to WCxA, WCxA itself, and so on, until its feeder connection and antenna. Thus: 7604 alarm is usually related to degraded receive quality of one sector or one TRx. From hardware point of view: Check its receive path from TRx unit, Rx main and RxDiv port, SMA cables from Rx port to M2xA, M2xA itself, and so on, until its feeder connection and antenna.

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Sample ND 196

Performance Analysis: IF: band q5 value is under 90% THEN: we suspect that the TRX have bad quality uplink or Downlink ( in this case downlink issue)

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Sample ND 195

This report shows for each TRX: Ave MS pwr attn /lb_11 Average MS power attenuation (dB) Ave BS pwr attn /lb_12 Average BS power attenuation (dB) Ave UL str /lb_9 Average UL signal strength Ave DL str /lb_10 Average DL signal strength . The signal (UL, DL) strength is given as value 0..63 (GSM 5.08) . 0 =less than -110dBm, 1= -110 to -109 dBm, 3= -109 to 108dBm . ... 62 = -49 to -48, 63=greater than -48 SAMPLE ABOVE : For Down link TX 1 and TX 2 have big differences , also for TX5 and TX6 for sec 2 For Uplink RX main having 3db diff in sec 1, for sec 2 have 9 db diff 12


Base on BTS installation standard that : “Uplink and Downlink between TRX in one sector is maks 3db”

Sample ND 232 ( Time advance) this site having overshoot issue

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Sample ND 232 this site having overshoot issue

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AUDIT ANTENNA and Neighbour

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Sample ND 153 ( handover)

• MancagarMD3 to CiropohMG2 and cisarunimg having 100% fail • MancagarMD3 to mancagar MG3 having 85 of 2144 sample call Fail

• This report showing incoming and outgoing handover 16


Exception for 7745 • 1. 2. 3.

7745 will keep occur for this condition : No have neighbors cell ( island or remote standalone) Landscape contour ( hill and valley) Obstacle

This exception need to be justify as long as the KPI value achieve

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Summary 1. Alarm 7745 occur due to Abnormal release Channel - Mostly in TCH 53,56,59 because of Handover, Call Setup Issue - SDCCH 4B because of antenna and feeder installation 2. Module M6HA should be part of BTS High Capacity 3. Correction related alarm 7745  software CX5 CD4 (replace CX4.1 CD4) 4. Many things that can lead to alarm 7745, it can be categorized as below :  Transmission issue, Power Related issue  Environment Related, Air Conditioning, Temperature  BTS HW problem related, Cooling Fan, Module faulty  BTS Antenna Line  Coverage Issue  Configuration Mismatch between BSC and BTS/MMI  Some existing problem in the old SW  Other maintenance activity in the BSC level

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Additional : RFI Site Procedure Objective: 1. To have better site integration verification procedure 2. To make sure that all functionality of the integration site already in place and being verified 3. To avoid unnecessary mistake on integration such as cross feeder (partial and full), Loose feeder and others functionalities.

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RFI Site Procedure Methodology: There are 3 group of site check of this test call procedure: a. Connected Mode - Mobile originated calls of voice services b. Cross feeder Check 1.Using Network Monitoring on TEMS/NEMO (for best result for recognizing cross feeder symptom, Move along main lobe of each cell ± 500 m, and make sure that we have the serving CI along the main lobe). 2.Make Test Call and notate the used TRX in case of Hopping TRX eg. (Synthesizer Hopping) Specific MAIO will represent specific transceiver according to system Configuration or Site parameter. In case of Baseband Hopping TRXs then Baseband hopping parameter shall be disable then individual test shall be carried out individually per TRX according to Database Site parameter. 3.Lock the Transceiver carrying BCCH Frequency and perform test number 2 until all TRXs in the same cell have been successfully verified 4.Locate the same treatment in the different sectors 5.Failed TRXs can trigger further analysis with the site inspection on possible wrong connection or swapped feeder/antenna c. Hardware Inspection - Antenna Type - Antenna azimuth - Antenna downtilt (Mechanical/Electrical) - Have feeder label and match with antenna d. Remarks for further finding on the field

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7745 Alarm Troubleshoot

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