Bipartite matching based user grouping for grouped OFDM-IDMA

In this paper, we present a novel user grouping method for grouped OFDM-IDMA systems. Aiming at maximizing the system capacity, we adaptively distribute users among the pre-allocated subcarrier groups according to their respective channel conditions. Using the notion of SNR evolution function, we first analyze the achievable capacity of the system and formulate the optimization problem as a weighted bipartite matching problem. Due to the analytically intractability of the SNR evolution function, we opt to use either the worst case or best case of the achievable capacity to approximate the original problem. Then Kuhn-Munkres method is employed to solve the approximated problems. The performance of the proposed scheme is evaluated by both theoretical analyses and simulations. Results show that with our proposed algorithm, the system capacity is markedly improved and is very close to the theoretical capacity upper bound.