A Simple Distributed Space-Time Coded Strategy for Two-Way Relay Channels

For two-way wireless relay networks (TWRNs), the simultaneous bidirectional transmission has been shown to outperform other strategies using decode-and-forward (DF) distributed space-time coding (DSTC), thanks to its high spectral efficiency. However, it has a rather high relay decoding complexity and cannot use the direct link between the communicating terminals. In this letter, we propose a simple DSTC transmission scheme for TWRNs that avoids the latter disadvantages at the same symbol rate and with a performance advantage at high powers. Our strategy allows the communicating terminals to use the direct link between them to achieve a higher diversity gain. An extension of the proposed strategy to the differential case is also discussed.