Turbo Trellis Coded multiple access

Abstract

We propose a new overloaded multiple access scheme based on Turbo Trellis Coded Modulations (TTCM) which, thanks to the high gain provided by turbo coded schemes, exhibits improved performance with respect to other solutions based on Trellis Coded Modulation (TCM). Turbo Trellis Coded Multiple Access (TTCMA) performs simultaneous transmission of multiple turbo-encoded and modulated data streams intended for users experiencing similar Signal-to-Noise Ratios (SNR). Stream-specific permutations are employed in turbo code interleavers to enable stream identification and separation at the receiver. An efficient solution for the generation of sets of such permutations is also provided. TTCMA overcomes known limitations of previous TCM-based schemes, achieving a high aggregate spectral efficiency even at low SNR by exploiting the large coding gains provided by parallel concatenated schemes when the size of the transmitted information words is large.