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11th May 2011 at 09:04 #66352ManiaGuest
what are the limits of SDCCH in ericson?
What information i have is that the upper limit is the number of TRXs in the cell,
if I have to go above this limit is there any possibility?
Also what would happen in concentric cells? What would happen once a DCS TRX gets down? (would SDCCH on GSM also get down) why what is the backend ‘ABIS’ related dependency?11th May 2011 at 13:22 #66353SHELDONGuest
The maximum number of SDCCH/8s you can define in an ericsson cell is 32.
However, there is also a limitation on the maximum number of SDCCHs you can define per TRX, defined by the BSC parameter MAXNOSDCCHTRX which has a range of 1-4.
The multiplexing/concentration method you use on the abis also puts a limitation on the number of SDCCHs you can define per TRX. For TRX signalling going through unconcentrated abis timeslots with throughputs 64, 32 or 16kbps, the maximum number of SDCCHs per TRX are respectively 4,2 and 1. For concentration factors of 4,3 or 2 (on a 64kbps abis), the maximum number of SDCCH per TRX are respectively 2,3 and 4.
Let me know if you need any further explanation.
SHELDON24th May 2011 at 05:22 #66354ManiaGuest
Just another question, does concentration factor relate to the optimizer on ABIS like one used for VSAT links to reduce bandwidth? If you can please explain the concept of concentration on ABIS.
Thanks24th May 2011 at 16:48 #66355SHELDONGuest
Yes, concentration is a way of optimizing the number of abis timeslots required for signalling.
By using concentration, the signalling(BCCH, SDCCH, FACCH, SACCH, etc) for a number of TRXs are sent on one abis timeslot. If you’re using a concentration factor of 4 (for eg), it means that the signalling information for 4 TRXs are ‘concentrated’ onto one abis timeslot.
Of course, it has drawbacks. If your concentration factor is too high, some of your signalling information can be lost, resulting in poor performance in your cells.