The challenge in optimal resource allocation to mobile Worldwide Interoperability for Microwave Access (WiMAX) subscribers has not been fully overcome by researchers. This research aimed at developing an optimal scheduling algorithm for WiMAX resource allocation based on an improved Particle Swarm Optimization (PSO) technique. In this work, an improved PSO based technique for allocating subcarriers and Orthogonal Frequency Division Multiplexing (OFDM) symbols to mobile WiMAX subscribers is proposed using sub-group formation. The entire WiMAX network environment is sub-divided into 7 layers, and seven distinct modulation and coding schemes are proposed to be used in transmitting packets to the subscribers located within the respective layers. An enhanced model for throughput maximization and channel data rate has been developed by implementing an improved PSO based WiMAX resource allocating algorithm. A maximum throughput/aggregate data rate of 1398Mbps was achieved, which represents 88.88% of the maximum achievable aggregate data rate of the system.