Reduced complexity sequential decoding scheme for the multiple trellis coded modulation (MTCM)

It has been shown previously that the multiple trellis coded modulation (MTCM) can perform better than the conventional TCM over fading channels and AWGN channels, at the cost of additional computations per trellis branch. Two methods for decomposing the MTCM are studied. The first method is the direct decomposition method, which can reduce the decoder complexity without sacrificing the BER performance. For those codes that can not be decomposed with such method, a bit-neglection method is developed. This method can also reduce the decoder complexity but with severe degradation in BER performance. Multiprocessing is then accommodated to circumvent the degradation. A new metric with variable parameter for sequential decoding over the fading channels is derived. Computer simulations are used to aid the studies of the relations between the performances, the variable parameter, and the multiprocessing scheme