Joint time-frequency-power resource allocation algorithm for OFDMA systems

This paper considers a joint radio resource allocation simultaneously at the frequency domain (sub-carriers) and the time domain (slot) and the power domain (power control) for downlink in OFDMA systems. The radio resource allocation problem is modeled as a cooperative game where a fairness criterion is enforced. Given a minimum rate requirement for each user, Nash bargaining model ensures all users to attain their minimum rate requirements, and to maximize the aggregate payoff of the users. To achieve the Nash bargaining solution (NBS) of the game, firstly, a time-frequency allocation algorithm is performed by assuming an equal power allocation. Secondly, using the Lagrange multiplier method and the adaptive modulation and coding (AMC) schemes, we can easily obtain an optimal allocation by estimating each user´s signal-to-noise ratio. Thirdly, an optimal power allocation algorithm is proposed to maximize the sum payoff. Simulation results show that the cooperative game acquired a good tradeoff between the fairness and the overall system capacity, comparing with the other two typical resource allocation algorithms of the maximizing system capacity and the max-min fairness algorithm. Moreover the proposed algorithms have complexity O(K*N*T), where K is the number of users in Systems, N is the number of subcarriers, and T is the number of slots in a frame.