Parallel interference cancellation technique applied to DS-OCDMA systems

This paper investigates the parallel interference cancellation (PIC) with hard limiter technique in direct sequence optical code division multiple access system (DS-OCDMA). The PIC technique consists of first estimating the interference by decoding all the non-desired users with a conventional correlation receiver (CCR), and then of removing the estimated interference from the received signal in order to detect the desired user. We study an improvement of this technique: PIC+HL, in which we use an hard limiter (HL) before the CCR of the desired user, in order to limit the interference term due to the non-desired users bad cancellation. We develop the theoretical PIC+HL error probability expression from the PIC one in the chip synchronous case, for optical orthogonal codes (OOC). We demonstrate that such receiver improves significantly the O-CDMA performances regards to conventional receivers