HYBRID WAVELENGTH HOPPING TIME SPREADING CODE-DIVISION MULTIPLE-ACCESS SYSTEMS/

The capacity of local area networks (LAN) can be increased substantial ly by amalgamating different access techniques, Wavelength division mu ltiplexing (WDM) and code division multiple access (CDMA) can both off er an asynchronous mode of communication and can be integrated into a hybrid system. Here, the characteristics of one particular approach to achieving a hybrid system, analogous to hybrid systems used in electr ical CDMA are examined. An optical CDMA concept using wavelength hoppi ng and time spreading is described employing prime sequences for both the hopping and the spreading pattern (prime-hop sequences), and proof s are given that the autocorrelation function has zero side lobes and that the crosscorrelation function is at most 1, In such systems, the number of possible stations is greatly increased as is the number of s imultaneous users. Code generation and correlation are described in de tail and networks for efficient code generation are analysed. It is sh own that the system offers increased security levels leading to a very secure transmission, The system is suitable for truly asynchronous hi ghly secure LAN applications.