Alarm description.ppt

Alarm 7745_Channel failure rate above defined threshold

For Company internal confidential use only

for internal use only

Contents •

 Alarm Definition as per NED

•

Reasons for Alarm

•

Troubleshooting

For internal Company confidential use only

for internal use only

Alarm Definition as per NED : 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. Parameters, with their default values, affecting the alarm:

ZEEN:TCHFR = TCH failure rate (20 %) SCHFR = SDCCH failure rate (80 %) PRDCFR = length of supervision period (60 min) CS = channel seizure threshold value (10) SMBNT = supervision start time (08-00) EMBNT = supervision end time (18-00)

For internal Company confidential use only

for internal use only

Supplementary information fields :

For internal Company confidential use only

for internal use only

HOW ALARM 7745 Works This alarm is generated if the percentage of abnormally ended transactions on SDCCH or TCH channels during a measurement period is greater than or equal to the alarm threshold defined by the operator. However, the alarm is not generated again for a channel with an already active alarm. There are separate alarm thresholds for the SDCCH and the TCH failure rates. when a SDCCH/TCH is released with the following error causes, the lost call counter is augmented. Both SDCCHs and TCHs, release because of: •

a channel activation failure

•

user actions

•

a BTS failure

•

an LAPD failure

•

a BSC signalling unit (BCSU) reset

•

 Abis problems

•

 A interface problems

•

a radio failure

•

a radio failure on an old channel during handover 

•

a radio failure on a new channel during handover 

For internal Company confidential use only

for internal use only

TCHs only, release because of: •

a transcoder failure

•

a transcoder failure on an old channel during handover 

•

a transcoder failure on a new channel during handover  The counter for lost calls during a measurement period is cleared at the end of each measurement period. The filtering of the alarm generation is achieved with a threshold value defined by the operator for the number of channel seizure requests. The number of channel seizure requests during a measurement period must be greater than or equal to the threshold value for the alarm to be generated . Although the Channel failure rate exceeded (SDCCH, TCH) supervision is channel-specific, only one alarm per TRX and channel type is generated during one measurement period. In the alarm printout, more specified information is given of the channel with the greatest failure rate. The system cancels the alarm at the end of the first such measurement period during which conditions for alarm generation are no longer met or in connection with user's locking and unlocking commands .

For internal Company confidential use only

for internal use only

Reasons for Alarm •

Hardware Issues:  –

•

•

BTS unit hardware failures (TRX, BB2F,WCxA,DVxA)

 –

Crossed feeder cables.

 –

Bad SMA cable , bad feeder quality or their improper connectivity.

 –

RSSI values on the main and diversity paths are differing a lot.

RF Issues:  –

BCCH Frequency used in MAL list

 –

Some segments in the network using same BCCH Frequency

 –

Value of TSC parameter is same as BCC value

 –

High Interference caused in the network

BSC/Network Issues:  –

 –

 –

For internal Company confidential use only

LAPD message distribution problem due to unused (floating) TRX signaling links on the BCSU concerned Telecom links overloading the BCSU Repeated Transmission Failures

for internal use only

Troubleshooting

The Troubleshooting document uses the Ultra site nomenclatures for e.g. WCxA. The document is equally applicable to Flexi EDGE BTS.Note: Flexi Edge BTS does not have BB2F unit. •

For BSC/Network Issues refer the followings: •

There are a number of BSC alarms and counters which may indicate that BSC load is a problem. ▪

▪ ▪ ▪

For internal Company confidential use only

for internal use only

Increase in counters 3005, 3038, 3039, 3040, 3041, 500627 (DAT files are needed to see these counters)  Alarms 1014, 2133, 2478, 2720, 3164  Alarms 2993 & 7745 may also be caused by BSC overload. Check the Transmission Links for any jitters, slips and BER.