On the construction of 2/sup n/ codes for optical code-division multiple-access

An optical orthogonal code (OOC), intended for optical code-division multiple-access (CDMA), is a collection of (0,1) sequences with good correlation properties (i.e., high autocorrelation peaks with low sidelobes, and low crosscorrelation values). A "serial" coding architecture for optical CDMA has been introduced and found particularly suitable for waveguide implementation with high power efficiency. Since the optical encoder is made of a serial combination of 2/spl times/2 optical switches with n of them being biased to a "mix-split" state, the generated OOC\´s, so-called 2/sup n/ codes, pose with a symmetric delay-distribution property. Various techniques for algebraically constructing such 2/sup n/ codes of weight 4 are presented. The upper bounds on the cardinalities of these codes are also provided.<>