so in the end the cell has 4 TCH TS, 1 PDCH TS, 1 BCCH TS and 1 SDCCH TS
when applying the Erlang B formula
4 channels @ 2% blocking = 1.05 erlang
so the values you are sharing are not abnormal. It is rather high though, one should expect about 2% congestion, not 6-10%. Did you properly activate the TCH Queuing ? Is T11 around 6 seconds ?
Also, try to decrease the max pdch to 4 instead of 5, and reduce the HIGH LOAD GPRS by 10%
it means the caller can wait 15 seconds in the queue. That seems humanly too long to wait, so caller might hang up by itself before the end of the queue. therefore your congestion will decrease… but it’s fake 🙂
(note: don’t put 15s on all your cells, because there is a limit on the total number of calls in queue at BSC level)
altogether, i think you can play around with GPRS parameters (max pdch and the high load gprs), and then reduce the T11 down to a more normal value (6 to 10 s)
Well, try and see…
keep me posted,
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