THE PERFORMANCE OF DIVERSITY COMBINING FOR FAST FREQUENCY-HOPPED NCMFSK IN RAYLEIGH FADING

Frequency hopping (FH) spread spectrum is a well known technique used in communications systems to provide protection against interference s uch as jamming. With fast FH (FFH) (one or more hops per transmitted d ata symbol), powerful and robust methods for diversity combining have been developed as an additional jamming countermeasure. These same tec hniques can be applied to reduce the effects of multiple access interf erence, and so can be considered for civilian CDMA applications. Altho ugh the performance of a FFH communications system can be degraded con siderably by fading, few results exist which show the effects of fadin g on the diversity combining process. In this paper, both analytic and simulation results are presented for several diversity combining meth ods in a Rayleigh fading channel, which is often considered to be the worst case. The performance of these combining methods in fading is co mpared with that in AWGN and multitone interference to determine which methods are effective against these degradations.