DEVELOPMENT OF AN IMPROVED SCHEDULING ALGORITHM FOR MULTICAST SERVICES OVER WiMAX NETWORKS USING PARTICLE SWARM OPTIMIZATION TECHNIQUES

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Department of Engineering

ABSTRACT
The challenge of optimal resource allocation to subscribers ofmobile Worldwide Interoperability for Microwave Access (WiMAX) has not been fully overcome by researchers. This research work developed 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 mobileWiMAX subscriberswasdeveloped using sub-group formation. The entire WiMAX network environment was sub-divided into 7 layers.Seven distinct modulation and coding schemes were used in transmitting packets to the subscribers located within the respective layers. The objective function was determined based on PSO for throughput maximization and channel data rate. An enhanced model for throughput maximization and channel data ratewas developed by implementing an improved PSO based WiMAX resource allocation algorithm. Simulation of different scenarios of WiMAX multicast service to mobile subscribers for the evaluation of Aggregate Data Rate (ADR) and Channel Data Rate (CDR) for each scenario were carried out.The results obtained for the various layers and uniform distribution of users over the entire layers based on the performance evaluation of the improved algorithm for ADR were 350Mbps, 525Mbps, 700Mbps, 1050Mbps, 1050Mbps, 1400Mbps, 1575Mbps and 1398Mbps. Similarly, for CDR the results obtained were 6.98Mbps, 10.48Mbps, 13.97Mbps, 20.95Mbps, 20.95Mbps, 27.94Mbps, 31.5Mbps and 28Mbps. Validation was done by comparing the results obtained using the improved algorithmwith those of Maximum Throughput Algorithm (MTA). The values of ADR obtained based on the published work of Araniti et al., (2012) using the developed algorithm when users were randomly distributed and restricted to exist within each of the layers 1, 4 and 7 were 694Mbps, 175Mbps, 525Mbps and 788Mbps. Similarly, the results obtained for the CDRwere 13.9Mbps, 3.5Mbps, 10.5Mbps and 15.8Mbps. The corresponding values for the MTA were 400Mbps, 100Mbps, 400Mbps, 500Mbps and 12.5Mbps, 2.5Mbps, 12.5Mbps, 12.5Mbps, respectively. ADR of 694Mbps was achieved, which represented 88.88% of the maximum achievable ADR of the system as compared to 400Mbps, which represented 80% of the maximum achievable ADR obtained using MTA. This showed that the developed algorithm performed better than the MTA by 8.88%.