Decode-and-forward cooperative transmission in wireless sensor networks based on physical-layer network coding

In order to tackle the problem of reducing the transmission delay of multi-data acquisition source nodes in wireless sensor networks, we propose a cooperative method based on decode-and-forward (DF) and physical-layer network coding. In this proposed method, the two source nodes simultaneously transmit the respective information to the relay node and the data sink node using the orthogonal carriers. The relay node demodulates the received information separately from two source nodes and employs quadrature phase shift keying to modulate these information before forwarding them. The data sink node decodes the information of two source nodes using log likelihood ratio based on the signals received from the direct link and the relay link. Simulation results of bit error rate and system throughput show that the cooperative method can effectively improve the performance of the cooperative system compared with the traditional DF.