Power Efficient Resource Allocation for Downlink OFDMA Relay Cellular Networks

Abstract—Resource allocation in orthogonal frequency division multiple access (OFDMA) relay cellular networks (RCN) has been investigated. We introduce an orthogonal frequency-and-time transmission (OFTT) protocol, in which orthogonal frequency and time resources are allocated to different communication modes and phases, respectively, and propose a simple algorithm for resource allocation. Communication modes (one- and two-hop modes), subchannels, and relay transmit power are sequentially allocated to enhance the power efficiency of the OFDMARCN.We show an achievable quality-of-service tradeoff between one- and two-hop users. Furthermore, we show that the relays consume pro-portional power to their own second hop channel gains, whereas a single selected relay uses its full available power. Network power and system throughput are evaluated to confirm that the proposed OFTT protocol with the sequential resource allocation is power efficient in OFDMA RCN. Index Terms—Orthogonal frequency division multiple access (OFDMA), orthogonal frequency-and-time transmission protocol, power efficiency, relay cellular networks (RCN), resource alloca-tion. I