Performance Analysis of Optical Code Division Multiple Access Technique for Metropolitan Area Network

Optical code division multiple access (OCDMA) allows signal to be transmitted in an asynchronous manner, and promises high flexibility and simplicity with considerable security. OCDMA harnesses an enormous bandwidth that provides high spectral utilization and efficiency to support multiple, simultaneous active users. However, this multiple access technique also has impairments such as multiple user interference (MUI) and signal dispersion over distance. Thus, traditional metropolitan area network (MAN) must be developed by considering system performance optimization. Optimization is typically achieved by increasing code length and system complexity, or by applying a high level of medium access control (MAC) supervision. Numerous code set developments have been proposed to overcome the aforementioned impairments. However, the proposed code sets have not been demonstrated in an actual optical system that supports multiple users, particularly in a MAN, which has various noise sources and MUI effects. Thus, the feasibility of these code sets cannot be verified with absolute certainty. Conventional OCDMA architecture and encoding stage also exhibit various deficiencies, including rigid synchronization, fiber delay line (FDL) accuracy issues, stability resulting from environmental fluctuations, high costs, difficulty in fabrication, lack of compactness, and spectral resolution issues. In this work, an optimized model is presented as an enhanced solution to the limitations of the existing approach to be applied in a MAN.