A simulation study of performance of joint soft demapping-viterbi decoding in DVB-T system

In this paper, we evaluate and compare the performances of Viterbi decoding schemes based on soft decision and hard decisions, with results applicable to the Digital Video Broadcast-Terrrestial (DVB-T) standard. The standard suggests that the BER ≤ 2 × 10^-4 at the decoder output is good enough for the quasi error-free condition. We assume that the channel state information (CSI) of all sub-carriers are available at the receiver at all times. The multipath fading is assumed to be Rayleigh type. Simulation results confirm the advantage of using soft-decision decoding over the hard-decision type. Approximate E_b/N₀ gains in the range 3-4.5 dB are reported for the different choices of code rates and OFDM transmission modes available in the standard.