Network coding with diversity and outdated channel state information

Physical-layer network coding (PNC) has the potential to significantly improve the throughput of wireless networks where the channels can be modeled as additive white Gaussian noise (AWGN) channel. As extending to multiple channels, this technique requires both amplitude and phase compensation at each transmitter and will lead to inefficient systems yielding no diversity even with perfect channel state information (CSI). In order to avoid these limitations, we apply network coding with diversity (NCD) to achieve a form of selection diversity and extend NCD to cooperative multiple access channels in this paper. However, in practical wireless communication systems, the CSI could become outdated due to the difference between the CSI used in the relay selection and data transmission phases. Hence, the selected relay may not be the best one during data transmission phase due to the dynamic change in the wireless channels. Therefore, we first explore the relation between the present and past CSIs. Exploiting this relationship, the NCD scheme with outdated CSI is investigated based on the past CSI. To evaluate the performance of this scheme, an information-theoretic metric, namely the outage capacity, is studied under this condition.