Performance Enhancement by Adaptive Resource Allocation in WiMAX Networks

Abstract

The powerful of WiMAX technique for providing the Subscribers (SSs) with a flexible interface to share resources is based on an Orthogonal Frequency Division Multiple Access (OFDMA). Conventional access schemes base on fixed parameters for all SSs in the networks without considering the effects of various channel characteristics among them. This motivates the authors to propose a new Adaptive Resource Allocation Scheme (ARAS) to construct the OFDMA based frame. The proposed ARAS integrates two approaches, the adaptive Cyclic Prefix (CP) length and dynamic frequency allocation. These two approaches are implemented, analyzed and evaluated based on the simulation of WiMAX frames in a dynamic manner resulting in a new frame pattern within each down link connection. The resulting frame shows the contribution of the time domain approach which represented by adaptive CP in mitigation ISI and ICI which improves the network performance in term of BER, where enhancement of 7 dB in SNR was gained at BER equals to 10-3 compared with the network which adopts fixed guard interval equals to 1/8. From the other side, the frequency domain approach, which represented by the dynamic frequency allocation proves its effectiveness in supporting the QoS requirements in term of data rate.