In Fig. 8, we depict the achievable MI at intercept receiver versus the distance between radar network and target Rmt for different confidence levels at radar network a and different distances between radar network and intercept receiver Rj. One can observe from Fig. that for all the cases, the achievable MI at intercept receiver is increased as the distance between radar network and target increases from Rne,= 5 km to Rne,= 100 km. As mentioned before, this is because that more radar modulating signal is transmitted to satisfy the requirement for target detection as Rnet increases, so less power is remained to generate CJ signal to jam the intercept receiver. Moreover, one can observe that as the distance between radar network and intercept receiver Rj decreases, the MI at interceptor is reduced, showing the LPID performance enhancement of exploiting CJ to defend against interceptors in radar network system.
4.2 Target Tracking with FCCP Based Security Information Optimization
This subsection presents the numerical results of our proposed security information optimization scheme in target tracking scenario. We track a single target by employing particle filtering (PF) method. For simplicity, it is assumed that the passive intercept receiver is carried by the target. Figure 9 shows one realization of the target trajectory for 50 s. Figure 10 illustrates the distance changing curve between radar network and target.
Fig. 8. Achievable MI at intercept receiver versus R„e, for different confidence levels a and different Rj.
increased as the confidence level a at radar network increases, which shows that there exists a restrictive relationship between the confidence level a and the achievable MI at intercept receiver. This is due to the fact that more radar modulating signal would be transmitted to satisfy the system requirement with the increase of confidence level at radar network. The radar modulating signal could be intercepted by interceptor easily, and the achievable MI at intercept receiver will increase subsequently. Moreover, the achievable MI at intercept receiver is reduced as the sensitivity of intercept receiver Simj„ decreases.