An adaptive fuzzy logic code allocator for 2-D OVSF coded OFCDM communication systems over dual selective fading channels

In this paper, we investigate the multiuser performance in a 2-D spreading orthogonal frequency coded division multiplexing (OFCDM) communication system over frequency and time selective fading channels. To compromise between the diversity gain and the multiple access interference (MAI), we propose an adaptive fuzzy logic to infer adequate 2-D spreading codes and to assign the OVSF codes to active users for OFCDM mobile communication systems. Moreover, we develop a look-up table to simplify the complexity. Simulation results show that the proposed both fuzzy logic code allocator (FLCA) and look-up table can not only suppress the MAIs induced by the non-orthogonality but also exploit the diversity gain over dual (time and frequency) selective fading channels.