Bit Error Rate Computations for Both Noise and Intersymbol Interference Considerations in Optical Communications

Bit error rate computation for optical communication systems incorporating equal­ izers and under both noise and intersymbol interference (ISI) is discussed. An ac­ curate method based on a saddlepoint approximation is used for the computation. Previous work based on saddlepoint approximation has considered only the use of ba­ sic integration-and-dump detection. When ISI is strong, this simple detection method is unsatisfactory. Instead, a raised-cosine filtering is often used to achieve minimal ISI. This thesis considers both integration-and-dump and raised-cosine equalizers. The use of equalizers other than integration-and-dump complicates the computation be­ cause of the complexity of the moment generating function involved. Two different input pulses are considered to study the effect of ISI. Results show that when inter­ symbol interference is strong, the use of raised-cosine equalizers can reduce intersym­ bol interference and improve the performance of the system significantly.