Bit repetitive trellis coded modulation for the Rayleigh fading channel

A new approach to the problem of bandwidth efficient coding for transmission over the Rayleigh fading channel is considered. The proposed scheme is based on the idea of trellis coded modulation, but supports the re-transmission of 50% of the sources´ information. This re-transmission of data provides an additional level of time diversity, and allows for the identification of a new distortion criterion which may be used along with the squared Euclidean distance, to find the maximum likelihood path through the trellis. This new approach is developed utilizing 4-state trellis codes, along with two and four dimensional constellations, to support an information throughput of 2 bits/T. We work through the design considerations applicable to this scheme, and provide performance comparisons between the proposed system, and TCM systems of comparable complexity. This new scheme achieves significant coding gains for bit error rates of practical interest. However, its complexity is about twice that of ordinary TCM.