Error probabilities of fast frequency-hopped MFSK with noise-normalization combining in a fading channel with partial-band interference

An error probability analysis is performed for an M-ary orthogonal frequency-shift keying (MFSK) communication system employing fast frequency-hopped (FFH) spread spectrum waveforms transmitted over a frequency-nonselective, slowly fading channel with partial-band interference. Diversity is obtained using multiple hops per data bit. A procedure referred to as noise­ normalization combining is employed by the system receiver to minimize partial-band interference effects. Each diversity reception is assumed to fade independently according to a Rician process. The partial-band interference is modeled as a Gaussian process. Thermal noise is also included in the analysis. Forward error correction coding is applied using convolutional codes and Reed-Solomon codes. Diversity is found to dramatically reduce the degradation of the noise-normalization receiver caused by partial-band interference regardless of the strength of the direct signal component. In addition, diversity offers significant performance improvement when channel fading is strong. Further significant performance improvement is obtained for higher modulation orders ( M > 2). Uncoded receiver performance with a diversity of four is roughly comparable to coded receiver performance with no diversity for ratios of bit energy-to-interference noise density in the range between roughly 12 and 22 dB. Substantial improvements in receiver performance are obtained by combining diversity, higher modulation orders, and coding