Error performance study of MPPM optical communication systems with finite extinction ratios

Multi-pulse pulse position modulation (MPPM) aims to improve the receiver bandwidth efficiency with respect to M-ary PPM. It is regarded as an attractive modulation scheme that can be utilized in both optical fibers and free-space optical (FSO) communication systems. In this paper, the error performance of MPPM optical communication systems over an ideal channel is studied, with consideration of the impact of the transmitter extinction ratio (ER) on the symbol error rate (SER). The study considers SER for symbol sizes M ϵ {16,32,64}. The values of the number of ON slots per symbol considered are N ϵ {1, 2, 3, 4}, and the ER values are r ϵ {10, 20, 30} dB. Monte-Carlo simulation shows that finite ER degrades the performance of MPPM systems. It also shows that MPPM systems, despite their improved bandwidth efficiency, have worse error performance than the M-ary PPM systems.