2G KPI

SD Block

SD Blocking means that you are not getting SD resource for the call origination. When MS connects with Network then RACH and AGCH are provided. After AGCH, SDCCH is provided but if SDCCH is not provided at this time due to some problem or due to unavailable of SD by BSC.

Reason for SD Blocking:

•         LAC Boundary

•         High Volume of SMS

•         SD utilization is high

•         Time Slot faulty

•         Wrong SD Dimension

•         Hardware Issue

SD Drop

When SD is assigned for a mobile during call connection process and during this time due to any problem or any mismatch occurs by which SD loss occurs, It is between allocation of SD and before TCH allocation.

Reason for SD Drop:

•         Overshooting

•         Shift the SD time slot

•         Interference(bcch clash)

•         HW Issue

•         Wrong parameter planning

•         Bad coverage

•         MAIO mismatch

•         High LAPD utilization

•         Wrong Power control settings

•         Check the Timer T 3101

•         Check the Timer T 200(20ms)

TCH call Blocking:- , it present how many subscriber asks for TCH channel and network reply with no available resource.so it present how many subscriber request TCH channel to reject this request

TCH call drop:-after subscriber get TCH and start conversation during it the call is dropped for some reasons not related to the subscribers .

Reasons for TCH Blocking:

High Utilization of TCH

Time slot faulty.

Lock TRXs.

HW Problem.

Solutions for removal of TCH Blocking:

Implement half rate or Dual rate.

Check FRL & FRU.

Add another TRX.

If TRX addition not possible, try to share the traffic of that cell with the neighboring cell by changing tilt or orientation.

Useful Report for TCH Blocking:

135 TCH Congestion

TCH Assignment Success Rate(TASR):-

Successful assignments show the number of successful TCH allocations at call setup.

TCH Assignment Success Rate = (Completed TCH Assignments/TCH Assignment Requests) x 100%

The following procedure should be performed for TCH Assignment analysis:

For TCH assignment success rate, the first thing, check the TCH Time Congestion.

If there is congestion on TCH, it is recommend doing the dimensioning and adding TRU based on carried TCH traffic demand.

If there is no congestion on TCH, check the output power of the BTS. If the output power is low, increase the output power.

If the output power is ok, check the faulty BTS by extracting BTS error log.

If hardware fault found, swap or repair HW.

Perform drive tests to check the coverage and received RxLEV.

If no dominant cell or similar signal strengths of a few cells found during drive tests, it is recommended to add BTS.

If there is no problem on the dominant cell, check the interference whether co-channel or adjacent channel.

Mostly, the problems of low TCH assignment are TCH availability and interference.

What is handover success rate:-

Handover Success rate means the rate of successfully transferring an ongoing call or data session from one channel to another in a cellular network.

How to improve HOSR in gsm:-

Need to send neighbor script

Rx quality:-

# Same BCCH or TCH pr BSIC will be there.

# Some cells are overshooting at that place.

# UL and DL interference may be worst which will be found in Reports 196,210 in Nokia.

some sites can overshoot above 5kms also

so check it out.. Check coverage level.. if there is a lake or river near by then interference occurs due to TIR..check whether neighbors are properly defined.. there can be a problem of handover failures,,, or change the orientation little bit.. then do post drive and observe..




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