Spatial modulation in two-way network coded channels: Performance and mapping optimization

In this paper, physical-layer network coding with spatial modulation in two-way relaying channels is studied. Two multi-antenna source nodes exchange information via a denoise-and-forward (DNF) relay node, and space shift keying modulation is employed in both source nodes and relay. The error performance in terms of average symbol error probability is evaluated. To further enhance the transmission quality, the denoise mapping operator is concerned to be optimized, and a graph-based approach is adopted to make the problem more tractable. Effective sub-optimal algorithm based on dichotomizing method is presented to reduce the solving complexity. Simulation results in terms of symbol error rate and throughput show that the DNF protocol with optimized mapper outperforms that with random or no mapper.