Asymmetric transmission for multimedia application in downlink multi-carrier CDMA channel

Multi-carrier CDMA (MC-CDMA) is one of the promising wideband transmission techniques for the fourth generation mobile communication. This paper studies the possibility to improve its performance in the downlink Rayleigh channel by proposing an Adaptive Code Length (ACL) scheme. One of the main reasons for performance degradation is the interference due to the fadingnature of the mobile channel. The ACL scheme has potential to reduce the amount of interference. The performance of the suggested technique has been done analytically and by simulations. A second level of adaptation, threshold adaptation, is also proposed to optimize the performance of the system under various conditions (number of users, Signal to Noise Ratio). ACL is then applied to transmission of two data with diflerent quality denoted as primary and secondary hits. Simulations are done to test the validity of the BER expressions and to further analyze the system behavior:This work is concentrated on Rayleigh fading channeL