Jammed FH-FSK performance in Rayleigh and Nakagami-m fading

Abstract

This paper looks at the performance of frequency hopped spread spectrum (FH) binary frequency shift keyed (FSK) modulated signals in wideband and partial-band noise jamming, when either the signal or signal and jammer are subject to Rayleigh or Nakagami-m fading. Simple bit error rate (BER) approximations are derived as functions of the signal and jammer fading parameters (which need not be equal) using the assumption that average jammer power is much greater than average signal power. The approximations are used to find the worst case jammer fractional bandwidth. For signals with Rayleigh or more severe fading, full-band jamming is the optimal attack. In less severe signal fading, partial-band jamming may be more disruptive, depending on the available jammer power. It is found that jammer fading improves communications channel performance with wideband jamming by 2-4 dB effective power gain. When jammer bandwidth is optimized, BER performance is dominated by the signal fading parameter, although the optimal jammer bandwidth will vary somewhat due to jammer fading. The accuracy of these approximations is verified by comparing them to more detailed numerical solutions.