Trellis Code Design for Spatial Modulation

In this paper, we propose a novel MIMO transmission scheme, called trellis coded spatial modulation (TC-SM) in which the trellis (convolutional) encoder and the spatial modulation (SM) mapper are jointly designed similar to the conventional trellis coded modulation (TCM). A soft decision Viterbi decoder, which is fed with the soft information supplied by the optimal SM decoder, is used at the receiver. We derive the pairwise error probability (PEP) upper bound for the TC-SM scheme in uncorrelated quasi-static Rayleigh fading channels. From the PEP upper bound, code design criteria are given and then used to obtain new 4-, 8- and 16-state TC-SM schemes using QPSK (quadrature phase-shift keying) and 8-PSK modulations for 2 bits/s/Hz and 3 bits/s/Hz spectral efficiencies, respectively. We show by computer simulations that the proposed TC-SM schemes achieve significantly better error performances than their counterparts at the same spectral efficiency with reduced decoding complexity.