Throughput–Delay Tradeoff of Proportional Fair Scheduling in OFDMA Systems

This work presents an analytical model of the throughput-delay tradeoff found in proportional fair scheduling used in orthogonal frequency-division multiple access (OFDMA) systems in the context of user multiplexing. For this purpose, we propose a simple and efficient resource allocation scheme based on 2-D resource partitioning in the frequency and time domains. Basically, frequency-domain partitioning is determined by the degree of frequency diversity, and time-domain partitioning determines the degree of multiplexing (DoM), which is the number of users to be served in a subchannel of a frame. We investigate the effect of the DoM and frequency diversity on the delay quality-of-service (QoS) performance of OFDMA systems by analyzing the effective capacity. In addition, an energy efficiency analysis in the wideband regime shows that insufficient frequency diversity increases the impact of the delay QoS constraint on energy efficiency, and in this case, greater energy efficiency can be achieved by using an appropriate DoM.