A frequency-hopped MFSK communication system for multiple access

A modified receiver for frequency-hopped MFSK (M-ary frequency-shift keying) for mobile communications is presented. This modified receiver provides an implementation advantage by eliminating unnecessary energy detection of all the frequency channels. A performance analysis of the proposed system is carried out by using the union bound. It is shown that an optimum number of message bits for a given number of simultaneous users exists, minimizing the word error probability. Error probabilities are calculated in the case of fixed bandwidth and for a fixed number of repetition tones. The effect of using error-correcting coding is also considered. This scheme is a generalization of the MFSK system that allows the message bits to be varied, making it possible for designers to increase the flexibility of the implementation