Integer Bits-Optimal Power Allocation Scheme with Proportional Fairness in OFDMA

Abstract:
A subcarrier-power-integer bits allocation scheme is proposed that is aimed to maximize the throughput of downlink OFDMA systems under constraints on both total available power and the proportional fairness among users. The scheme is implemented in a two-step allocation procedure: initial integer bits allocation, and power reallocation. One distinctive feature of the proposed scheme is the reallocation of the remaining power due to the allocation of initial integer bits to subcarriers, which leads to significantly increasing the system’s throughput. Simulations are made to evaluate the throughput as a function of SNR and active users’ number, respectively, the rate proportionality as a function of the users’ number, and the variation of the used power versus SNR. Comparison of the proposed scheme is carried out with two existing non-integer bits allocation schemes without and with considering rounding off. The comparison of simulation results shows that the proposed scheme can achieve the similar performance to the two schemes’ (without rounding -off included), and the better performance than the two schemes with rounding off, in terms of system throughput.