Maximum achievable number of users in optical PPM-CDMA local area networks

摘要

An optical code-division multiple-access (CDMA) communication network employing optical orthogonal codes is considered. The data symbols of each multiple-access user is encoded, before multiplexing, using pulse-position modulation (PPM) technique with sufficiently large pulse position multiplicity. The concepts of both users rate and users strength are introduced. Using these concepts an achievable number of simultaneous users that can be accommodated by the optical PPM-CDMA channel, while keeping the transmitted information per photon fixed and maintaining the probability of error below some prescribed threshold 0>/spl epsiv/>1, is determined. Furthermore, it is shown that the users strength has a simple positive characterization and in turn it is possible to load the entire subscribers simultaneously into the optical channel and embrace arbitrary small error rate.