Performance comparison of optical receivers using different filtering algorithms and modulation schemes

This paper compares the performance of optical receivers that use phase shift keying (PSK) and low pass filtering techniques. The filtering techniques that are discussed in this paper are Average filtering, Viterbi & Viterbi algorithm and Weighted Viterbi & Viterbi algorithm. Step-by-step implementation of the optical transmission system with AWGN and linear phase noise is discussed. Low pass filtering is done by obtaining the sum of most recent (2N+1) samples with suitable coefficients, where N is the Filter Width of the low pass filter. The suitability of the QPSK modulation scheme is observed by comparing QPSK modulation scheme with BPSK modulation scheme and 8-PSK modulation scheme.