During the period of 12/1/2005 -5/30/2006, we expanded our research from generic wireless sensor networks to radar sensor networks. For radar sensor networks, we performed the following preliminary studies:1. Waveform design and diversity in radar sensor networks with applications to automatic target recognition without or with delay-doppler uncertainty. We used constant frequency (CF) pulse waveform and linear frequency modulation (LFM) waveform in this study. 2. We proposed a Knowledge-based Ubiquitous and Persistent Sensor networks (KUPS) for threat assessment, of which "sensor" is a broad characterization concept. It means diverse data or information from ubiquitous and persistent sensor sources such as organic sensors (e.g., radar) and human intelligence sensors.3. Spatial-temporal-frequency diversity to improve the detection performance of Radar Sensor Networks in the presence of certain types of interference (clutter, jamming, noise and interference between radar sensors) was studied.For non-radar sensor networks, we continuously conducted the following research tasks:1.
20060620043RSN and propose maximum-likehood (ML)-ATR algorithms for nonfluctuating target as well as fluctuating target. Simulation results show that our waveform diversity-based ML-ATI{ algorithm performs much better than single-waveform ML-ATR algorithm for nonfluctuating targets or fluctuating targets. Conclusions are drawn based on our analysis and simulations and future research works on this research topic are discussed. In the above ATR using CF pulse waveform design and diversity, we assumed no delay-doppler uncertainty. It is not true for ATR in target search phase because the target range and mobility are not yet perfectly known, which results in delay-doppler uncertainty. In [3] [4], we studied linear frequency modulation (LFM) waveform design and diversity, and applied it to ATR with delaydoppler uncertainty using ML-ATR algorithm. Simulation results show that our RSN vastly reduces the ATR error comparing to a single radar system in ATR with delay-doppler uncertainty.In [6], we studied waveform design and diversity using some concepts from physical layer communications such as orthogonal, non-coherent detection, and coherent detection. We also used signal representation from communication domain, i.e., taking its real part when carriers are considered. We proposed orthogonal waveforms for RSN, which eliminates interference when no doppler shift is introduced. Additionally, this approach applies the advantage of spacial diversity through equal gain combination performed by clusterhead. When doppler shift is considered and interference is unavoidable, we analyzed the performance of this design not only in coherent RSN, but in noncoherent systems as well. The latter scenario is more challenging as doppler-shift uncertainty results in more complicated implementation. Monte Carlo simulation shows that our technique provides much better detection performance than single radar for fluctuating targets, in terms of probabili...