FDL Design in Time-Wavelength Switched Optical Networks

An all-optical approach to reduce the speed mismatch between electronic sources and high-speed wavelength channels is to time-division multiplex low-capacity circuits onto each wavelength, and switch time-wavelength-slots within the network. In such a Time-Wavelength-Switched Network (TWSN), fiber delay lines (FDLs) and wavelength conversion (WC) can increase the flexibility in connection slot scheduling and decrease the connection blocking probability. In this paper, we examine the impact of various FDL configurations and WC on a CrossConnect's performance by looking at its ability to schedule as many connections as possible from a given traffic matrix. We present several crossconnect architectures and develop graph formulations that can be used to optimally solve the scheduling problem. Using numerical simulation results, we then compare several FDL configurations. Results show that FDL configurations and WC could play an important role in determining performance.