Repeated-permutation MPPM/CDMA with interference avoidance and cancellation

To realize the high throughput performance in the optical wireless communications effectively, a Repeated-permutation Multi-pulse Pulse Position Modulation (RMPPM) system with interference avoidance and cancellation is considered. The RMPPM system can transmit the bit data using the repeated-permutation of the slot positions and several orthogonal codes. The RMPPM system can improve the throughput performance of the conventional PPM systems in the single user case. However, with increasing the number of code per frame, Multiple Access Interference (MAI) also increases in the multi-user case. To avoid MAI, we consider a Reduction Rule (RR) of orthogonal codes at a transmitter. On the other hand, we apply an Interference Cancellation (IC) using modified prime codes at a receiver. As results, BER can be greatly improved by RR and IC. The RR and IC is the effective way for the RMPPM system in the multi-user case of optical wireless communication.