On the Robust Detection of Hidden RF Receivers Through the Controlled Backscattering Characteristics

Hidden radio frequency (RF) eavesdroppers pose a growing threat to wireless communication security due to their passive and covert nature. This paper presents a non-invasive framework for detecting such passive receivers by leveraging controlled backscattering characteristics of wireless devices. The proposed approach modulates the power supply states of suspected eavesdroppers to induce distinguishable variations in their backscatter signatures, enabling detection without requiring the target to transmit. Two complementary detection schemes are developed: 1) an energy detection (ED) scheme utilizing signal amplitude fluctuations, and 2) a cyclostationary feature detection (CFD) method exploiting inherent signal periodicity. Analytical models characterize detection, false alarm, and error probabilities under practical channel conditions. The framework mitigates the critical distance limitations of prior art by eliminating dependence on path-loss estimation and relying on intrinsic hardware-dependent backscattering properties. Sensitivity analyses provide operational guidelines on observation time and environmental stability. The framework reduces dependence on path-loss estimation by exploiting intrinsic, hardware-dependent backscattering characteristics. It offers analytical bounds and implementation criteria for next-generation wireless security and cognitive radio systems.