Radio Link Timer

**peanut** · 2012-01-27, 09:04 PM

Dears,

I would like to change the RLT for a region, I would like to know how to choose a correct value

The recommended value is 20 for city and 32 for rural

Regards,

**Finetopix** · 2012-01-27 09:04 PM

**plannerguy** · 2012-01-28, 02:47 PM

Hi

Just keep 24 in city and 32 outside ...

will defnitely help to reduce TCH drops

Regards
Plannegruy

**adewijaya** · 2012-01-28, 03:08 PM

@ plannerguy, best value at your suggestion. Don't forget with ARLT if you implemented AMR Feature (differencies is 10). ex : RLT 24 put ARLT 34

**peanut** · 2012-01-29, 03:30 AM

What's the relation between AMR and RLT?

**rfoptman** · 2012-01-29, 03:49 AM

Originally Posted by peanut

What's the relation between AMR and RLT?

In AMR, the quality of call even with lower C/I is acceptable so it's less sensitive to higher RLT making it possible to maintain a call with more RLT value!

**badi** · 2012-01-30, 02:31 AM

RLT = 28 with AMR and RLT = 20 without AMR should be ok

**Muhammad Imran Rafique** · 2012-01-31, 03:18 PM

Hi Plannerguy,

Look the technical reason for having higher value of RLT in case of AMR is as

during the speech in GSM, TCH and SACCH/FACCH data is transitted over the structure of 26 TDMA frames. Please note AMR variation is only applicable on speech, so there are chances if we increase RLT, the connection can be saved. We increase time as logically there are chances that connection qaulity improves and rescued.

After AMR, one known issue is the subscriber may get clean voice till call drop. Reason is that speech data is protected due to AMR (error connection and Dectection) BUT SACCH remains the same.

So it is recommended to have higher values of AMRRLT. hope it is clear now.

BR//
Imran

**fahmi** · 2012-01-31, 07:17 PM

Originally Posted by Muhammad Imran Rafique

Hi Plannerguy,

Look the technical reason for having higher value of RLT in case of AMR is as

during the speech in GSM, TCH and SACCH/FACCH data is transitted over the structure of 26 TDMA frames. Please note AMR variation is only applicable on speech, so there are chances if we increase RLT, the connection can be saved. We increase time as logically there are chances that connection qaulity improves and rescued.

After AMR, one known issue is the subscriber may get clean voice till call drop. Reason is that speech data is protected due to AMR (error connection and Dectection) BUT SACCH remains the same.

So it is recommended to have higher values of AMRRLT. hope it is clear now.

BR//
Imran

Please Muhammad Imran Rafique, I need more explanation, I still don't understand why we have to keep AMR with higher RLT ??
Many thanks

**Muhammad Imran Rafique** · 2012-01-31, 08:18 PM

Dear Fahmi,

Attached document is explaining the scenario with details. Just keep in mind AMR will not impact on SACCH (bits), i mean they are not adaptive with varing C/I.

RLT is responsible to release call which is purely based on SACCH frame decoding, it expect the same quality for speech bits also. in case of AMR this is not the case.

BR//
Imran
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