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Abstract In a unified system of passive radar and communication systems of joint transmitter platform, information intended for a communication receiver may be eavesdropped by a passive radar receiver (RR), thereby undermining the security of communications system. To minimize this information security risk, in this paper, we propose a unified passive radar and communications system wherein the signal-to-interference and noise ratio (SINR) at the RR is maximized while ensuring that the information secrecy rate is above a certain threshold value. We consider both scenarios wherein transmissions of the radar waveform and information signals are scheduled with the disjoint (non-overlapping case) as well as with the same set of resources (overlapping case). In both cases, the underlying optimization problems are non-convex. In the former case, we propose alternating optimization (AO) techniques that employ semidefinite programming and computationally efficient semi-analytical approaches. In the latter case, AO method based on semi-definite relaxation approach is proposed to solve the optimization problem. By changing the threshold value of the information secrecy rate, we then characterize the performance tradeoff between passive radar and communication systems with the boundaries of the SINR-secrecy capacity regions. The performance comparison of the proposed optimization methods demonstrate the importance of the semi-analytical approach and the advantage of overlapping case over non-overlapping one. [ABSTRACT FROM AUTHOR]

Detection of unmanned aerial vehicle (UAV) is a challenging problem for passive bistatic radar (PBR) because of its low radar cross-section (RCS). Range migration (RM) will occur within one long coherent processing interval, which makes it difficult to increase coherent integration gain and improve radar detection ability. In order to eliminate the RM, a novel coherent integration method based on stretch processing and chirp-z transform (CZT) in the frequency domain is proposed. Firstly, stretch processing is applied to correct RM. Then, CZT is performed to mitigate the residual range offset and achieve coherent integration of the target's energy according to each Doppler cell. The advantage of the proposed method is that it can obtain superior coherent integration and detection performance compared to existing methods. Numerical and experimental results are presented to demonstrate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

To overcome the severe space-time adaptive processing (STAP) performance degradation caused by array gain/phase (GP) errors and undesirable random range sidelobe couplings, a novel cascaded suppression method based on joint iterative optimization is proposed for airborne passive radar. The proposed cascaded method (CM) exploits the sparse nature of these undesirable sidelobe couplings, reformulates the sparsity recovery problem as a joint optimization problem of the spatio-temporal profile and array GP errors, and achieves sidelobe couplings suppression before STAP. A range of simulations is conducted to test the proposed method. [ABSTRACT FROM AUTHOR]