Bit error rate computations for both noise and intersymbol interference considerations in optical communications

摘要

Bit error rate computation for optical communication systems incorporating equalizers and under both noise and intersymbol interference (ISI) is discussed. An accurate method based on a saddlepoint approximation is used for the computation. Previous work based on saddlepoint approximation has considered only the use of basic 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 because 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 intersymbol interference is strong, the use of raised-cosine equalizers can reduce intersymbol interference and improve the performance of the system significantly.