Multi-stage multi-user detection assisted asynchronous fast-FH/MFSK

A multi-stage multi-user detection (MUD) scheme designed for asynchronous fast frequency-hopping/multilevel frequency-shift-keying (fast-FH/MFSK) systems is proposed. Each signal detection interval is divided into sub-intervals and the MUD is applied to each sub-interval. The MUD exploits the explicit knowledge of the hopping addresses assigned to users. The received signal level is attenuated by a constant scaling factor, when it is deemed to be overwhelmed by multi-user interference. For the sake of preventing erroneous detection events, when communicating over frequency-selective fading channels, the scheme also invokes a space diversity technique. In the investigated scenario, the achievable bit error rate (BER) was reduced by as much as an order of magnitude in comparison to that of a conventional MUD scheme, when transmitting over an AWGN channel. For transmission over a channel exhibiting uncorrelated frequency-domain fading, selection diversity was used for the sake of achieving a reduced BER.