A bandwidth efficient signaling for MFSK systems

The use of a multiple-tone modulation scheme for a M-ary frequency shift keying (MFSK) system proves to be an efficient alternative for bandwidth constraint channels. A combinatorial design, called balanced incomplete block design, used to select the signaling format based on blocks of frequencies rather than single tones, as in a conventional MFSK system, is shown to reduce drastically the system bandwidth requirement and also to improve the performance of the system of a Rayleigh fading type of channel by adding an implicit diversity to the system. A nonbinary block code concatenated to the multi-tone MFSK system is considered, and it is shown to increase the diversity of the system, and consequently to improve its performance