hi Sukma
rahul is right for the first.In Nokia system default value for this alarm is 30db.If the Rx signal strength in a perticuler sector is differs by 30db in main and diversity cables this alarm comes up.u can change the thereshold value but its not advisable bcz above 30 db diff diversity is useless.so chek both the feeder of that sector for any VSWR or connectorisation issue.secondly channel failure rate shows the value of counter for TCH or SDCCH failure in perticuler time slot of any TRX.Subfield u can easily identify which time slot is creating problem or for which channel means for TCH or SDCCH.