I just found about this forum and I think this is really useful! I am an RF engineer working for an operator using Nokia BSS and we have a site that is having many SDCCH drops (around 60%) on a LAC change border with 2 TRX. It used to work fine until 1 month ago.
We have alarm 7745 CHANNEL FAILURE RATE ABOVE DEFINED THRESHOLD but we have checked both TRX with a loop test and they seem to work properly, we changed SDCCHs from one TRX to another without any improvement.
We have checked interferences, cables, masses and Baseband cards but it has not improved.
Do you have any ideas what the problem could be and how to solve it?
thanks very much in advance!