noise, at Pb = 10-5. Eb/N, dB Figure 2.61. Comparison of performance of FH/MFSK systems with optimum diversity in worst case independent multitone jamming as a function of K = logM. Best performance for small P (large E/N is achieved for 8-ary signalling. Non-Coherent Frequency-Hopped Systems the type of jamming), the P upperbounds for worst case jamming with opti- mum diversity have the form multitone noise jamming (2.126) jamming where 8 is enumerated in Table 2.10. With the caveat that our comparisons are based on exponentially tight upperbounds, it would appear that the worst case n = 1 band multitone jammer is the most asymptotically effective of those considered against FH/MFSK signals with optimum diversity for K > 2. Although Table 2.10 suggests that partial-band noise is more effective than band multitone jamming for K = 1, it must be stressed that 8 is pessimisti- cally low for the partial-band noise case since it is based on a Pb upperbound, while the n = 1 band multitone 8 is exact; so, it is conceivable that even in this case n = 1 band multitone jamming is the winner. When we analyzed the performance of FH/MFSK signals without diver- sity in worst case jamming, we saw that for small enough P's, the n = 1 band and independent multitone jammers were equally effective (see Figure 2.21). We argued that the reason for this equivalence is that the worst case independent multitone jammer sets the probability p that a given FH slot is jammed SO small that a jammed M-ary band is likely to contain a single jam- ming tone, just as in the n = 1 band multitone structure. Table 2.10 shows that with optimum diversity, n = 1 band multitone jamming is more effec- Table 2.10 Pb upperbound exponential coefficients (see (2.126)) for FH/MFSK signalling with optimum diversity in worst case jamming of various classes. The smaller 8 is, the more effective the jammer is for a given E/N, at low . The upper bound for n = 1 band multitone jamming and K = 1 is identical with the exact performance. Pb Bound Exponential Coefficie