BER analysis for multi-carrier DS CDMA with multi-rate traffic

In this letter, we present bit error analysis (BER) of orthogonal multi-car rier direct sequence code division multiple access (DS-CDMA) system with mu lti-rate (multimedia) traffic. Analysis is carried out with random signatur e codes for an AWGN channel. Interference in such a system is severe becaus e ail users of all media transmit over the same assigned sub-carriers. This makes the analysis difficult. In our analysis. we divide this interference into different types and carry out our analysis to obtain the BER taking i nto account all these types. Wee show that the performance of the system is improved as the number of assigned sub-carriers hi increases until a limit where the improvement does not continue even when M increases more. This i s because of. as we show, the interference due to other subcarriers becomes constant even in the case of M --> infinity, and the interference in a mul ti-rate multi-carrier system is bigger than that in a single-carrier (M = 1 ) by a factor of pi (2)/3.