Extensions of turbo trellis coded modulation to high bandwidth efficiencies

We extend turbo trellis coded modulation (TTCM) with punctured component codes to allow higher bandwidth efficiency. Two techniques, that can also be combined, were investigated that achieve this: the inclusion of uncoded bits in TTCM in conjunction with high order modulation (e.g. 64-QAM), and the replacement of two dimensional component codes (e.g. Ungerboeck codes) with multi-dimensional codes. In the first approach, the inter-set distance of the partitioning tree can be used to fix the number of coded and uncoded bits, which will strongly determine the complexity of the decoder. Simulation results are presented for 8-PSK with 2.5 bits per symbol and 64-QAM with 5 bits per symbol; they indicate that the scheme can achieve good bit error rates close to Shannon's limit.