Abstract
Multi-user orthogonal frequency division multiplexing (MU-OFDM) allows multiple users to transmit simultaneously on different subcarriers during the same symbol period and which is a promising technique for achieving high downlink capacities in future cellular and wireless local area network systems. The resource allocation of MU-OFDM is the subcarrier and power allocation among users sharing the same OFDM spectrum. An efficient resource allocation algorithm can improve the spectrum efficiency and support the quality of service requirement. In the previous literature, some resource allocation algorithms cannot ensure the fairness among users in advance. This thesis considers an allocation scheme of subcarriers and power to each user for maximizing the sum of users’ data rates, and subjecting to constraints on the total transmit power and proportional fairness among users’ data rates. Since the computational complexity of optimal solution and iterative root-finding method for achieving the constraints are extremely high, we propose a low-complexity suboptimal algorithm to satisfy the constraints. In the proposed algorithm, we divide the total transmit power into two parts such that a portion of the total power uses in the subcarrier allocation algorithm for attaining the coarse proportional fairness and the rest power is used in the power allocation algorithm for increasing minimum proportional data rate and fulfilling the better proportional fairness. Additionally, a range of deciding how much the power will be allotted to the subcarrier allocation algorithm is also derived. The simulation results demonstrate that the proposed algorithm can satisfy the proportional fairness and achieve about upward 98% capacity of the optimal power algorithm in [11].