Performance analysis of synchronous optical CDMA systems with EWO signaling

AbstractThe EWO signaling scheme has been proposed as an optical CDMA system. In this scheme, two orthogonal codewords with equal weights are assigned to a set of users. Depending on the transmitted information, one is selected for code spreading. Unlike the OOK signaling scheme, which is the fundamental optical CDMA system, the scheme is superior because the receiver threshold at the time of decoding need not be estimated dynamically. The EWO signaling scheme has been evaluated in an asynchronous system with OOC and PSC as the signature code. Although its error rate characteristic depends on the code used, there is no significant improvement over that of the OOK signaling scheme, and in fact the error rate may be worse depending on the conditions. This paper evaluates the error rate when the EWO signaling scheme is applied to a synchronous system. MPSC is used as the signature code. An ideal link is assumed in which all causes of noise other than interference from other channels can be neglected. Analytical evaluations and computer simulations are carried out. It is found that the EWO signaling scheme has much better error rate characteristics than the OOK system. In particular, by engineering the assignment of the codewords to each user, the EWO signaling scheme achieves an error rate of 0 regardless of the number of multiple users. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 87(12): 37–48, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10164