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Reply To: C/I and C/A


C/A = rxlev(serving cell) – rxlev(adjacent channel)
with adjacent channel = a channel which is adjacent to the serving channel by -1,-2,-3, +1, +2, +3 offset. (depends o your configuration)

C/I = rxlev(serving cell) – rxlev(cochannel)
with cochannel = same frequency as serving cell.

they can all be +ve or -ve ! but it happens that in a gsm network, only the cochannel interference are very dangerous. So frequency planning needs to pay particular attention to C/I, and keep it as high as possible.

for C/A, it can be negative since it won’t affect voice quality.