Performance of a Novel Fuzzy-Based Code Allocator for Two-Dimensional Spreading OFCDM Communication Systems

In this paper, we investigate the multi-user performance in a two-dimensional (2-D) spreading orthogonal frequency coded division multiplexing (OFCDM) communication system over frequency and time selective fading channels. To compromise between diversity gain and multiple access interference (MAI), we propose an adaptive fuzzy inference system to infer adequate 2-D spreading factors and to assign the orthogonal variable spreading factor (OVSF) codes to active users for OFCDM mobile communication systems. Simulation results show that the proposed fuzzy-based code allocation (FBCA) scheme not only suppresses the MAIs induced by non-orthogonality but also exploit the diversity gain over time and frequency selective fading channels and then outperforms the orthogonal code allocation (OCA) scheme at all system loads.

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