A New Family of 2-D Codes for Fiber-Optic CDMA Systems With and Without the Chip-Synchronous Assumption

In this paper, we propose a new family of wavelength-time codes, which are based on one-dimensional optical orthogonal codes (1-D OOCs) of cross-correlation functions of at most two. By relaxing the maximum cross-correlation values to two, the new 2-D codes provide larger code cardinality for accommodating more subscribers and support heavier code weight for better code performance. It is known that the traditional chip-synchronous assumption used in the analyses of optical codes gives a pessimistic performance upper bound, while the newer chip-asynchronous assumption offers a more accurate analysis. The performance of the new 2-D codes is here analyzed under both assumptions for comparison. Under certain conditions, our results show that the new wavelength-time codes outperform our recently reported multiple-wavelength OOCs and 2-D codes, which were based on 1-D OOCs of cross-correlation functions of at most one and two, respectively.