Performance of a fast frequency-hopped noncoherent MFSK receiver over Rician fading channels with either partial-band interference or multi-tone interference

Abstract

An error probability analysis is performed for a conventional noncoherent M-ary orthogonal frequency-shift keying (MFSK) receiver employing fast frequency-hopped (FFH) spread spectrum waveforms transmitted over a frequency-nonselective, slowly fading Ricean channel with partial-band noise interference. Each diversity reception is assumed to fade independently. The partial-band interference is modeled as a Gaussian process. The effects of wideband thermal noise are also included. The energy per hop is held constant; thus, as diversity increases, energy per symbol increases. Previous analyses considered only constant energy per symbol systems, however, practical military systems are likely to employ fixed hop rates. There is some performance enhancement to be obtained from implementing diversity in a conventional FFH/MFSK system with fixed hop rates, but partial band interference still results in significant degradation. Additionally, the performance of this FFH receiver is investigated over the same channel in the presence of partial-band tone jamming without diversity for the case of binary frequency-shift keying (BFSK) when both the signal and the jammer can fade independently. Performance when only a single jamming tone per hop slot is allowed is compared to that obtained when two jamming tones per hop slot are possible. When the jamming signal experiences Rayleigh fading there is very little degradation of the jammer's effectiveness as compared to when the jamming signal is not affected by fading