PERFORMANCE OF FAST FREQUENCY-HOPPED MFSK RECEIVERS WITH LINEAR AND SELF-NORMALIZATION COMBINING IN A RICIAN FADING CHANNEL WITH PARTIAL-BAND INTERFERENCE

An error probability analysis is performed for both a self-normalized and conventional M-ary orthogonal frequency-shift-keying (MFSK) noncoherent receiver employing fast frequency-hopped (FFH) spread-spectrum waveforms transmitted over a Rician fading channel with partial-band interference. The partial-band interference is modeled as a Gaussian process. The self-normalization receiver employs a nonlinear combination procedure to minimize performance degradation due to partial-band interference. The performance of the conventional receiver is found to be significantly degraded by worst-case partial-band interference regardless of the modulation order or number of hops per data symbol used for all channel conditions. The self-normalization receiver, on the other hand, can provide a significant immunity to worst-case partial-band interference for many channel conditions when diversity is used, provided the signal-to-thermal noise ratio is large enough to minimize degradation due to nonlinear combining losses. The improvement afforded by higher modulation orders is dependent on channel conditions with a significantly greater improvement obtained for Rician channels as compared with Rayleigh and near-Rayleigh channels.