Cooperative quadrature physical layer network coding in wireless relay networks

This paper proposes a cooperative quadrature physical layer network coding (CQPNC) scheme for a dual-hop cooperative relay network, which consists of two source nodes, one relay node and one destination node. All nodes in the network have one antenna, and the two source nodes transmit their signals modulated with quadrature carriers. In this paper, a cooperative quadrature physical layer network coded decode-andforward (DF) relay protocol (CQPNC-DF) is proposed to transmit the composite information from the two source nodes via the relay node to the destination node simultaneously to reduce the number of time slots required for a transmission. The proposed CQPNC-DF relay protocol is compared with time-division multiple-access amplify-and-forward (TDMA-AF), TDMA-DF, cooperative network coded DF (CNC-DF) and cooperative analog network coded AF (CANC-AF) relay protocols to demonstrate its effectiveness in terms of bit error rate (BER) and system throughput under different propagation conditions. The simulation results reveal that the proposed CQPNC-DF relay protocol can significantly improve the network performance. Compared with two TDMA schemes and CNC-DF, the proposal can provide up to 100% and 50% throughput gains, respectively.Moreover, no matter what the scene, the proposed scheme always has the lowest BER in the low SNR region.