Coherent Detection of Frequency-Hopped QPSK and QASK Systems with Tone and Noise Jamming

Abstract

Perfectly coherent demodulation provides a lower bound on the bit error probability (BEP) of any spread spectrum system. Here the performance of coherent QPSK and QASK systems combined with frequency hopping (FH) or frequency-hopping direct-sequence (FH/PN) spread spectrum techniques in the presence of a multitone or noise jammer is shown. The worst-case jammer and worst-case performance are determined as functions of the signal-to-noise ratio (SNR) and signal-to-jammer power ratio (SJR). Asymptotic results for high SNR show a linear dependence between the jammers' optimal power allocation and the system performance.