Diversity achieved by multiple tone FSK over fading channels

In multiple tone-frequency shift keying (MT-FSK), frequency diversity is achieved by transmitting several tones simultaneously; thus it is a more powerful extension of the conventional M-ary FSK modulation. The selection of the signal set is based on the balanced incomplete block design (BIB-design) from the combinatorial theory. We show that by combining the frequency diversity of MT-FSK signals with the time diversity of a fast frequency hopped (FFH) system, substantial improvements in performance can be obtained.