Physical-layer network coding (PNC) enables bi-directional communications with wireless decode-and-forward (DF) relaying to achieve the frame exchange within half of time slots required the conventional wireless DF relaying. However, to apply precoding to the frames transmitted from a terminal station to the relay station, the terminal station should acquire the channel state information (CSI) to the relay station before transmitting. In this manuscript, we propose a PNC-DF relaying protocol, in which a terminal station estimates the CSI to the relay station with echo-MIMO estimation. The throughput of the PNC-DF relaying protocol is evaluated using the CSI by echo-MIMO estimation and it compares with those of conventional relaying and XOR-NC relaying. As a result, the appricable domain of the PNC-DF relaying protocol is shown according to the distance between both of terminal stations.
