Two approaches to multilevel QAM coding

A systematic way of designing high gain moderate latency multilevel trellis coded modulation is developed. Various multi-level geometrically uniform partitions of 2D-QAM are investigated such that they lead to the 8-way 'Ungerboek' partition which allows up to 6 dB gain over uncoded modulation. The mod-lambda multilevel capacities determine the possible allocation of rates in the different levels, and hence decide overall latency. Group coding techniques are used to design the component codes, and simulations and bounds are provided for the proposed multilevel schemes. The question: "how much complexity is required to achieve an effective coding gain (excluding shaping) of 6.0 dB at BER 10/sup -7/...10/sup -10/ with moderate latency and practical multistage decoding?" is addressed.