Hybrid wavelength and code division multiple access in optical networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines t he best features of both. In particular, the hybrid scheme retains the larg e information carrying capacity of wavelength division multiple access (WDM A) and flexibility of code division multiple access (CDMA). In this paper W DMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA netwo rks, concept of incoherent and coherent coding including inverse decoding a nd matched filter is introduced. The delay performance of both WDMA and WCD MA networks, under the simple suboptimum access protocols based on cyclic s earch, is computed. It has been shown quantitatively that tuning delay sign ificantly affects the delay performance of both WDMA and WCDMA networks. Fu rthermore, delay performance of WCDMA networks is always better than the WD MA networks for the same tuning delay, load, and number of users.