Communications diversity advantages for the Mobile User Objective System

The UHF radio frequency (RF) band available for the our future military Mobile User Objective System (MUOS) satellite communications system has to contend with the signal scintillation effects encountered from propagation through the ionosphere as well as multipath signals from terrestrial signal reflections that will be prominent with new handheld terminals. These effects cause signal fading which can severely degrade the communications performance, but fortunately there are a multitude of diversity techniques which can greatly improve the performance as well. In this report we consider: (1) implicit channel diversity over (1a) coherent bandwidth limited channels and (1b) time dispersion by using interleaving and coding, as well as (2) explicit channel diversity employing different (2a) carrier frequencies and (2b) propagation paths. All these techniques can gainfully be used with the MUOS although frequency diversity may be less applicable on the UHF Earth terminal uplink. The material presented should be useful in the system design and evaluation of various system realization concepts.