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12th February 2010 at 11:34 #61033TheDarkKnightGuest
Our whole network is AMR enabled, yet during the drive test, the call sometimes goes on EFR instead of AMR HR/FR. What could be the possible reason?
Thanks/12th February 2010 at 19:39 #61034BijoyGuest
Does this occurs only for few cells or for all cells??12th February 2010 at 22:59 #61035TheDarkKnightGuest
Yes, only for a few cells. not all the cells. And also, it does not happen on those cells all the time.13th February 2010 at 04:26 #61036BijoyGuest
Check for speech versions in use in these cells.
Bijoy13th February 2010 at 07:16 #61037Mahesh Kumar SinghGuest
This is happening becuase of there is possibilities that EFR is used and threshold value is set in such manner that if there is low call volume then call is opted to switched in EFR.EFR provide better quality and SQI as compare to AMR.This is realy a good feature that during low call volume all call is initiated in EFR.13th February 2010 at 07:49 #61038PixGuest
In ALU system, if a MS is AMR and the AMR feature is enabled, the call are always initiated in AMR. It is going to be AMR FR if cell is low loaded and AMR HR if cell is loaded.
The AMR FR codec list contains a codec at 12.2 kb/s, which is equivalent to the EFR. So AMR FR should provide exactly the same quality as EFR.
The Dark knight : which system are you using ?
Is it possible that TEMS does a mistake ?
Within the same cell, do you see that the codec is changing AMR -> EFR -> AMR ? Normally, that shouldn’t be possible.
The codec could change from AMR to EFR only during an intercell HO, if the target cell does not support AMR.
pix15th February 2010 at 12:27 #61039TheDarkKnightGuest
@Pix: I am using Nokia 2G. TEMS making a mistake can definitely be a possibility.
The call stayed on EFR for a certain cell. When that route was driven after a couple of weeks, the call stayed on AMR FR.
Mahesh’s reasoning does make sense, although I am not aware of any feature of this kind in Nokia.
THanks/15th February 2010 at 12:35 #61040PixGuest
Well, EFR and AMR FR provides the same voice quality and uses the same capacity…
What Mahesh Kumar Singh has said could be true, but I don’t understand why a constructor would implement this. If the call is started in EFR, it cannot move to AMR anymore (within the same cell). It’s smarter to start it in AMR if possible, so it enjoys the possibility to switch become AMR sub-codecs quickly if needed.
Another possibility : perhaps your AMR license is limited : only a certain number of calls can use the AMR at the same time, in your network.
pix21st February 2010 at 19:52 #61041TheDarkKnightGuest
Hmm … Yes that could be the case.
Thanks for your inputs, everyone22nd February 2010 at 13:39 #61042BijoyGuest
You can rule out the possibility of Licence in Nokia system for sure.As in Nokia,if you are low on AMR license,you can never activate AMR on that cell or TRX ,in fact,u can never create the TRX if AMR is enabled in your BSC & you are low on license.