Study of a spread spectrum subcarrier multiplexed optical network.

Abstract

This thesis investigates the performance of a hybrid modulation scheme, combining subcarrier multiplexing and code division multiple access. This scheme may be useful in tomorrow's optical local area networks to take advantage of the capacity of optical fibers using commercially available optical technology. The application of subcarrier multiplexing to optical local networks has generated much interest recently, however it is sensitive to nonlinear distortion generated by the laser diodes used to transmit data over the optical network. Earlier research has indicated that combining code division multiple access with subcarrier multiplexing may provide improved performance. However the lasers' nonlinearity has not been specifically included in earlier research, due to the complexity of the analysis. In this thesis a simulation is used to evaluate the performance of the hybrid SCM-CDMA optical network. A custom program was written in the C language for this purpose. Preliminary results from the simulation program indicate that the performance of subcarrier multiplexed signals sent over an optical network may improve fairly substantially if code sequences are used to spread the bandwidth of information signals prior to optical transmission.