Space–Time Trellis Codes for Two-Way Relay MIMO Channels With Single-Antenna Relay Nodes

In this paper, the analysis and design of space-time trellis codes (STTCs) for two-way relay channels (TWRCs) with multiantenna source and destination and single-antenna relay nodes, assuming perfect channel state information (CSI) at the destination nodes, is considered. We derive a pairwise error probability (PEP) expression for the performance of STTCs in this type of channels. A simple upper bound on the PEP is then derived and used to find optimum STTCs. We prove that the designed STTCs based on the derived criterion achieve full diversity and significant coding gain in TWRCs, particularly at high signal-to-noise ratios (SNRs).