Multi-user receiver based on co-channel interference cancellation for multilevel FSK/FH-spread spectrum multiple access system

A multi-user receiver is presented based on cancelling cochannel interference (CCI) in MFSK (multilevel frequency shift keying)/FH-SSMA (frequency hopping spread spectrum multiple access) system, in which the address code is used as a hopping sequence to hop the carrier frequency in MFSK. The address code is useful to separate the desired user´s signal from the undesired ones in a decoder, but it cannot always correctly decode them when many users´ signals are overlapped or hit in SSMA. The proposed receiver uses the time-frequency matrices decoded by the address codes of all users in order to eliminate such hit undesired user tones or CCI and to decide all users´ data correctly, assuming that the address codes of all users are known in SSMA. BER performance is evaluated by theoretical analysis and computer simulation in order to show improvement of user capacity or the increase of the number of simultaneously accessing users