Iterative demodulation and decoding of coded non-square QAM

  • Authors:

  • Lifang Li;Dariush Divsalar;Samuel Dolinar

  • Affiliations:

  • Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA;Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA;Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA

  • Venue:
  • MILCOM'03 Proceedings of the 2003 IEEE conference on Military communications - Volume I
  • Year:
  • 2003

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Abstract

It is shown that a non-square (NS) 22n+1 -ary quadrature amplitude modulation (QAM) can be decomposed into a single-parity-check (SPC) block encoder and a memoryless modulator in such a way that the inherent block encoder has a recursive nature. When concatenated with a forward-error-correcting (FEC) code, iterative demodulation and decoding of the FEC code and the inherent SPC code of NS-22n+1 -QAM is then possible. The capacity and bit/symbol-error-rate (BER/SER) performance of coded and uncoded NS-22n+1 -QAM systems are given and compared to those of other 22n+1 -ary systems. Simulation results show that, with iterative demodulation and decoding, coded NS-8QAM performs 0.5 dB better than standard 8QAM and 0.7 dB better than 8PSK at BER= 10-5, when the FEC code is the (15, 11) Hamming codes concatenated with rate-1 accumulator codes, while coded NS-32QAM performs 0.25 dB better than standard 32QAM.