Techopedia explains Slow Frequency Hopped Multiple Access (SFHMA)
SFHMA has the ability to provide inherent frequency diversity and to beneficially randomize the impact of co-channel interference. It can also be usefully combined with the innovative Space-Time-Shift Keying (STFSK) scheme.
SFHMA can avoid the prolonged fade issues that are often experienced by slow-moving or stationary mobile stations (MSs). This is due to the fact that hopping to another independently- faded frequency may reduce fading. The classic SFH900 mobile system showcased the advantages of SFHMA. SFH900 mobile system was centered on "mixed" slow frequency hopping (SFH) blended with time division.