DS‐CDMA outage performance over a mobile satellite channel

Abstract

Abstract A DS CDMA satellite uplink with power control error is considered. CDMA system performance is normally interference limited, and, in an additive, white, Gaussian noise channel, with many users, sufficient processing gain, and effective power control, individual users typically experience the average performance over all users. In this case, the other users appear as the equivalent of additional Gaussian noise and each user experiences the same environment. An alternative measure of performance under fading conditions is the probability of outage. For coded signals, the fading must be averaged over all the symbols in the code word. For properly interleaved signals and i.i.d. Rayleigh fade statistics, the average must be performed over a chi‐squared variate. The probability of outage, defined as the probability that the decoded bit error rate exceeds a specified threshold, is monotonic with the probability that the chi‐squared variate is less than a specified threshold. We derive upper and lower bounds on the outage probability for soft decision decoding.