Novel Detectors for Passive Radar Sensing With I/Q Imbalance and Additive Distortion

Abstract

Passive radar has been recognized as one of the most attractive and promising approaches to solving the critical challenge of spectrum scarcity. However, the ubiquitous hardware impairment (HWI) might severely degrade the passive radar's performance. This article develops maximum likelihood estimate algorithms considering I/Q imbalance (IQI) and additive distortion (AD) to propose the generalized likelihood ratio test (GLRT) based detectors. For single-target cases, the novel GLRT detectors correspond to different knowledge levels of the transmitted signals and channel state information. Then, the single-target scenarios are extended to the two-target case to investigate the effects of transmitter-receiver distance, bistatic range and range resolution brought by the interfering target. Specifically, we propose the HWI mitigation algorithm to approximate and simplify the complex GLRT expressions due to the interfering target, thereby counteracting the effects of IQI and AD. Finally, simulation results demonstrate that both amplitude mismatch and phase mismatch have degrading impact on the overall detection probability of single-target passive radar, and the twotarget detector has a very high range resolution compared with classical works in DVB-T. Also, the range resolution is proven to be robust to HWI.