12th October 2011 at 21:11 #59051
c/i is a difference of two rxlev’s.
rxlev(C) = -70dBm
rxmev(I) = -90dBm
therefore C/I = -70 – (-90) = +20dB
dB is not a proper unit. it is only a “tool” to compare two levels in dBm.