Resource-Allocation for OFDMA Multi-Hop Relaying Downlink Systems

This paper proposes resource-allocation algorithms to maximize the sum-rate in orthogonal frequency-division multiple-access multi-hop relaying downlink systems. With advance subchannel allocation to users and relay stations, Lagrange dual-decomposition solves the power-allocation problem. This paper shows the optimal solution to be a modified water-filling algorithm, where an inner-outer bisection method determines the optimal water-levels. Further, proposed heuristic resource- allocation algorithms rely on the Karush-Kuhn-Tucker conditions. Simulation results show that the multi-hop OFDMA relaying systems outperform the conventional OFDMA systems by more than 30% with use of the proposed resource-allocation algorithms.