Rate and Power Adaptation for Physical-Layer Network Coding with M-QAM Modulation

Abstract—Physical-layer network coding (PNC) is an effective strategy for increasing the throughput of wireless networks. In the current literatures, PNC without rate and power adaptation is mainly focused. Realizing that the transmission efficiency can be improved through rate and power adaptation in wireless networks, this paper focuses on developing a rate and power adaptation scheme for PNC. Through formulating how the data rate and transmission power affect the bit error rate (BER) of involved links in PNC, we observe that with a given data rate, the transmission power has to satisfy some constraints. Using these power constraints, we obtain a candidate set of optimal transmission power. By traversing the candidate set and the data rates supported by nodes, a rate and power adaptation scheme is developed. To test its performance, we apply the proposed scheme into an existing PNC-supported MAC protocol. Simulation results demonstrate that the proposed scheme can improve the throughput and delay performance in various scenarios. Index Terms—Denoise-and-forward (DNF), physical-layer net-work coding (PNC), rate and power adaptation, wireless net-works. I