Reduced complexity decoding of space time trellis codes in the frequency selective channel

An iterative approach is developed for decoding space time trellis codes (STTCs) in frequency selective multiple input multiple output (MIMO) channels. The method uses the partitioned Viterbi algorithm (PVA) as an equaliser for the MIMO system. It is used iteratively with a STTC decoder that provides soft outputs using the soft output Viterbi algorithm (SOVA). It is shown through simulation that the iterative procedure achieves a performance within 2.0 dB of maximum likelihood (ML) decoding, at a FER of 10^-2, but suffers a small diversity loss. It is also shown that the complexity of the iterative approach is lower than that of ML decoding.