Physical-layer network coding with partial CSI

In this paper, we investigate the physical-layer network coding (PNC) with partial channel state information (CSI) in the context of two way relay communication. We consider the typical scenario that one end node exchanges information with another via a relay without knowing the CSI knowledge between the relay and the other end node. A relay scheme called power weighted mapping (PWM) is proposed to implement the PNC with partial CSI, which is actually working by mapping the observations at the relay to a specific sending constellation. For the case of QPSK modulations at the end nodes, we develop another two relay schemes called 3QAM mapping (3QAMM) scheme and QPSK mapping (QPSKM) scheme to improve the performance, under the principle of increasing the minimum distance of the constellation at the relay. The simulation results demonstrate the effective of our proposed schemes, which greatly reduce the system load while still reserve high performance of about only 1dB performance loss compared with the schemes with full CSI.