Performance analysis of OFDMA System with multiple data rate in Rayleigh fading channel

Cellular communication systems need to support simultaneous transmission of multiple data rates over the same medium. A major aspect of design of cellular systems is simultaneous sharing of channel resources avoiding multiple access interference between users. For high quality communication this must be done without severe degradation in performance of the system. Orthogonal frequency division multiple access (OFDMA) is a multiple access technique that can accommodate many users with widely varying applications, data rates and quality of service requirements. This paper presents analysis of transmission of multiple data rates by using orthogonal variable spreading factor (OVSF) codes in an OFDMA system, which gives increase in spectral efficiency. The performance of the system is analyzed using bit error rate (BER), for additive white gaussian noise (AWGN) and Rayleigh fading channels.