Joint multi-user interference and clipping noise cancellation in uplink MC-CDMA system
In this paper, an iterative method is proposed to jointly cancel multi-user interference and clipping noise in uplink Multi-Carrier Code Division Multiple Access (MC-CDMA) systems. Clipping is the simplest method to overcome high peak-to-average power ratio of multi-carrier signals but it makes the signals distorted. Reconstruction methods use non-distorted samples to reconstruct distorted samples in the receiver but multi-user interference causes the methods do not work properly because all the received samples are distorted due to clipping and interference and so there is no undistorted samples to be used in recovering clipped samples. On the other hand, multi-user interference cancellation methods do not work properly because clipping in the transmitter is a non-linear process and therefore this process increases the amount of multiple access interference (MAI). In this paper, we propose a joint MAI and clipping noise cancellation method. In the proposed iterative method in each iteration a MC-CDMA detection method accompany with a clipping and filtering process and then by using the received signal as reference signal, an approximation of error due to clipping and residual interference is computed. Simulation results show that the proposed method improves the performance of clipped MC-CDMA systems in uplink for synchronous/asynchronous links.
iterative methods signal reconstruction signal detection interference suppression multi-user detection