CSMA-and-NOMA-based Random Massive Access in Power Line Communication for Smart Gird Applications

Abstract

In power line communications (PLC), because of the severe channel condition, the access resource is limited and the network is unable to accommodate massive clients in future smart grid applications. However, non-orthogonal multiple access (NOMA) enable users to share the limited time and frequency resource. In this paper, an access scheme based on carrier sense multiple access (CSMA) and NOMA is proposed, where more than one user can access to the channel and transmit the packets in the same time slot and frequency band. Then, the optimal decoding order is obtained with the power allocation of primary users. To analyze the collision rate of the proposed scheme, the process of users transmitting data packets is modeled as a Markov chain, and the collision rate with higher access number is proved to be decreased. Meanwhile, the system throughput increases due to higher data rate of the multi-user channel and lower collision rate. Numerical results indicate the superior performance of the proposed protocol with high network load.