Perturbation methods for canceling interference in CDMA systems

Based on perturbation theory, formulas for multi-user detection in CDMA systems are derived. Starting from the single user detection and applying iterative perturbations to correct for interference, we obtain better linear combination amplitudes for codes of the multi-user waveform and hence, lower bit error rate (BER). The amount of computation is much reduced by calculating the interference in frames and sliding the 3-symbol-window for all users.