Green resource allocation for MIMO-OFDM relay networks

This paper studies the joint resource allocation problem of antenna, subchannel, transmission power, and phase duration for the relay-enhanced bidirectional multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) networks. The goal of resource allocation is to minimize the transmission energy in the networks with multiple relay stations (RSs) under the data rate constraints of user equipment (UE). The challenges of this resource allocation problem arise from the complication of multiple-phase assignments within a subchannel since the RS can provide an additional transmission path from the base station to the UEs. The green resource allocation (GRA) schemes with reduced computational complexity are proposed in this paper to develop the joint resource allocation algorithm for the UEs with the consideration of direct and two-hop communications. Both the separate downlink (DL) and uplink (UL) and mixed DL and UL relaying assignments are adopted to obtain the solutions for proposed GRA schemes. Simulation results show that the GRA schemes can provide comparably better energy conservation with the consideration of quality-of-service (QoS) support.