An analytical model of iterative interference cancellation receiver for orthogonal/orthogonal overloaded DS-CDMA system

One of the efficient schemes to overload a CDMA system is to use two sets of orthogonal signal waveforms (O/O) Sari, Vanhaverbeke and Moeneclaey, IEEE Communication Magazine, 56-59, 2000. In this paper, we have presented the analysis of hard decision interference cancellation (HDIC) receiver for O/O overloaded DS-CDMA system. A closed form expression for the average bit error rate (BER) is obtained, for each stage of HDIC receiver, without considering the correlation between the multiple access interference and Gaussian noise. It is observed that at lower overloadings, analytical result matches closely to that obtained from simulation. But there is a difference between two at higher overloadings. The reason for such a difference is the inaccuracy in variance calculation due to the assumption of zero correlation. By using the Price's theorem, we have obtained the correlation between tentative data decision and Gaussian noise samples. The overloading performance of a specific Quasi-synchronous sequence (QOS) O/O scheme is also evaluated using interference cancellation receivers. © 2010 Springer Science+Business Media, LLC.