Optimised Constellation Prerotation for 3-Terminal 1-Relay Network with Wireless Network Coding

Wireless (Physical-Layer) Network Coding (WNC) is an interference harnessing physical-layer concept combining network coding principles and broadcast nature of the wireless medium. Significant capacity gains of WNC were shown in a wireless 2-Way Relay Channel (2-WRC). Extension of WNC to more complicated network topologies potentially offers even larger gains than in the 2-WRC. However, such an extension is generally non-trivial. In this paper, we show that it is feasible to achieve additional considerable capacity gains in comparison to bidirectional relaying approach in a three-terminal one-relay network. We focus on the constellation design for its uplink (Multiple Access Channel (MAC) stage). The throughput maximisation is achieved by an optimised prerotation of source constellations, effectively reducing a number of required MAC stages.