Optimal Asymmetric Resource Allocation for Multi-Relay Based LTE-Advanced Systems

In this paper, we propose a novel asymmetric resource allocation (RA) scheme for the decode-and-forward (DF) multi-relay based Long Term Evolution Advanced (LTE-Advanced) system, with the orthogonal frequency division multiplexing (OFDM) modulation. Given a fixed total transmit time duration, the time slot durations for the two hops via each of the K relays are designed to be asymmetric, which increases the degree of freedom for transmission significantly. We propose an optimal algorithm to maximise the system capacity, with joint asymmetric time allocation, power allocation, and subcarrier selection/allocation. Simulation results show that the proposed asymmetric RA scheme provides an enhanced performance over algorithms with symmetric time slot allocation, and it is also robust against the variation of relay nodes´ locations.