investigating the RTC drop is easy :
does it happen on several BSC ?
does it happen on a whole BSC ?
does it happen on only few BTS ?
only one BTS ?
only one cell ?
only one TRX ?
If 1 or many BSC : are they all connected to the same TC ?
thanks to “AIC” (a-interface) counters in NPO (AIC is the name of an object, such as Cell, Adjacency, TRX, etc), you can detect in which Ater-mux timeslot there is a failure.
Since you say that it occurs only when the traffic is high, then I would suspect a board to be faulty, either in 1 BSC or in 1 TC. Again, refer to the investigation method above… Normally, the traffic is allocated randomly on the BSC or TC boards, so the traffic should not influence the % of RTC drops.
Please share your QoS stats here 🙂