Combined Tone and Noise Jamming Against Coded FH/MFSK ECCM Radios

It is knownlhat partial-band tone jamming (PBTJ) is generally the worst form of jamming for frequency-hopped M-ary FSK (FH/MFSK) communication systems. Recent studies show that for some coded systems, full-band noise jamming (FBNJ) is more effective than worst-case PBTJ if a receiver is able to utilize jamming state information (JSI) for decoding, when the symbol energy-to-uniform noise jamming power spectral density ratio (E, ,” , ) is small. In this paper, we conjecture that a proper combination of PBTJ and FBNJ under a given total jamming power constraint may be more effective than PBTJ alone, not only for the case with low E , / N , but also for the case with high E < / N , , since the FBNJ can corrupt the JSI. Assuming this combination of PBTJ and FBNJ jamming, we consider three cases of receiver processing-the hard decision (HD) metric without JSI, the HD metric with perfect JSI, and the maximum likelihood (ML) metric using Viterbi’s ratio threshold (VRT) to generate a I-bit symbol decision quality indicator. System performance is evaluated in terms of the Chernoff bound on the probability of symbol error. From extensive numerical analysis we conclude the following. For the case of the HD metric without JSI, PBTJ-only jamming is the worst form of jamming as expected since the receiver does not use JSI at all; for the other cases, a combination of PBTJ and FBNJ is the worst, with the worst ratio of PBTJ power to FBNJ power a function of the values of M and E , / N J .