Buffer-Assisted Physical-Layer Network Code Designs for Cooperative Systems

In this work, we present buffer-aided physical-layer network coding (PLNC) schemes and develop novel PLNC algorithms for cooperative direct-sequence code-division multiple access systems. In the proposed buffer-aided PLNC schemes, we employ a relay pair selection algorithm to select the relay pair and the packets in the buffer entries with the best performance and the associated link combinations used for data transmission. We then develop PLNC algorithms based on the design of linear network coding matrices using maximum likelihood and minimum mean-square error criteria to generate the network coded symbols that are sent to the destination. Simulation results show that the proposed techniques significantly outperform prior art in sum-rates and bit error rates.