r FH/QPSK in noise jamming with Eb/No = 20 dB. Performance of FH/QPSK in the Presence of Partial-Band Noise Jamming Ep=3dB Pwc 0.5 Ep=6dB ED=15 LB ED=12dB =12 dB Eb/Ny,dB Figure 1.11. Worst case p versus E,/N/-FH/QPSK (noise jamming). Eb=3dB Ep=6dB Po max Eb/N,,BB Figure 1.12. Worst case Pb versus EJN-FH/QPSK (noise jamming). Coherent Modulation Techniques jammer, namely, > 0.7090 (1.72) E6/N,=0.7090 and a corresponding maximum average bit error probability Eb/N J > 0.7090 (1.73) Eb/No->00 Figures 1.10-1.12 characterize the performance of FH/QPSK in the pres- ence of noise jamming, as computed from (1.66). 1.4 PERFORMANCE OF FH/QASK IN THE PRESENCE OF PARTIAL-BAND NOISE JAMMING Assuming the same noise jammer model as that discussed in the previous section for FH/QPSK, the average symbol error probability of FH/QASK- 16 is then given by (1.24), with Pso as in (1.51), but now (1.74) The limiting behavior of (1.24), together with (1.51) and (1.74) as Eb/No approaches infinity is simply (1.75) which yields a partial-band fraction for the worst case jammer given by the solution to (1.76) Performance of FH/QASK in the Presence of Partial-Band Noise Jamming (1.77) Numerical solution of (1.76) yields 0.7921 > 1.9802 (1.78) Eb/N, V 1.9802 and a corresponding worst case average symbol error probability Eb/N, > 1.9802 Eb/No->00 1.9802. (1.79) The average bit error probability Pb is obtained from (1.57), where Pbo is given by (1.60) and Pb, is given by (1.80) (1.81) The limiting behavior of Pb as Eb/No approaches infinity is then lim Pb = p[30(xoo) + 10(3xx) - 1Q(5xx) (1.82) where Xx is the corresponding limit of X in (1.81), namely, (1.83) The worst case jammer is found through a procedure analogous to the one in Section 1.3: (1.84) Eg/N  1.758 Coherent Modulation Techniques and a corresponding maximum average bit error probability of 0.1555 Eb/N J > 1.758 Eb/No->00 lim Eb/N  1.758. (1.85) It is interesting to note that the ratio , computed from (1.79) and (1.85) is 0.2728, which is slightly higher than the approximate valu