SUPPRESSION OF MULTIPLE ACCESS INTERFERENCE IN UPLINK OFDMA OF MOBILE WiMAX

Abstract

In Orthogonal Frequency Division Multiple Access (OFDMA), a set of orthogonal subcarriers has been assigned to each user for simultaneous data transmission. OFDMA is more sensitive to synchronization errors that lead to Carrier Frequency Offset (CFO) at the base station receiver. This results in Multiple Access Interference (MAI) and Inter Carrier Interference (ICI) which leads to degradation in the performance of Mobile WiMAX system. In this paper, a novel Fuzzy minimum output energy (MOE) receiver for uplink OFDMA in Mobile WiMAX system is proposed. The proposed receiver consists of Coarse CFO estimator, Fuzzy CFO constrained detector, Maximum Ratio Combiner (MRC) and Signal Subspace Projection techniques. Fuzzy CFO constrained detector collects multipath energy and suppresses MAI. It ensures the suppression of MAI and ICI, thereby improving the performance of Mobile WiMAX system. Simulation results show that the proposed Fuzzy MOE receiver has better performance in Frequency Mean Square Error (FMSE) than Zeng and Leyman (ZL) and Zhao and Haggman (ZH) algorithms.