Frame error rates for convolutional codes on fading channels and the concept of effective E/sub b//N/sub 0/

Abstract

Estimation of Viterbi decoder performance over channels with time-varying received signal levels is the subject of this paper. This work is motivated by a desire to obtain good estimates of the frame error rate (FER) for convolutional codes with bit-level interleaving over fading channels subject to practical power control algorithms. The convolutional code performance is quantified through the FER and effective E/sub b//N/sub 0/. where the latter is defined as the E/sub b//N/sub 0/ on an additive white Gaussian noise (AWGN) channel that results in the same FER. Given a received vector of (time-varying) E/sub b//N/sub 0/ values, we compute analytic estimates for the probability of frame error and the effective E/sub b//N/sub 0/ for a Viterbi decoder and interleaver combination. In particular, we validate our analysis using the R=1/3 convolutional code and interleaver used on the IS-95 CDMA reverse channel. Comparisons with simulations show that even for E/sub b//N/sub 0/ vectors with very large variations, our proposed estimates are good to within 0.2 dB for the effective E/sub b//N/sub 0/, giving FER estimates within a factor of two-five of the simulations.