Wireless sensing is recognized as a promising technology for next-generation wireless networks, utilizing signals from devices such as Wi-Fi to detect and interpret human information, including movement status and sleep quality. However, the broadcast nature of wireless signals poses significant privacy risks, as unauthorized users may intercept these signals, leading to potential privacy breaches. Given the sensitive personal information embedded in CSI data and the limitations of encryption at the transmission end, conventional privacy protection measures are inadequate. Thus, developing physical layer-based privacy protection technologies for wireless sensing is urgently needed. In this paper, we consider a wireless sensing system model addressing privacy leakage issues and characterize wireless sensing performance as a classification problem. We propose a novel multi-antenna signal processing-based privacy protection strategy. To illustrate the fundamental tradeoff between sensing and privacy protection, we model the wireless sensing process as a communication task based on non-cooperative joint source-channel coding and introduce the concept of a sensing rate region. Our main contribution is the characterization of sensing and privacy protection performance at two key points within the sensing rate region:POS, indicating the minimum achievable sensing rate of an illegitimate receiver constrained by the maximum sensing rate of a legitimate receiver, andPOPP, indicating the maximum sensing rate of a legitimate receiver constrained by the minimum sensing rate of an illegitimate receiver. Based on our analysis, we provide strategies to establish achievable boundaries betweenPOSandPOPP. Moreover, we define the secure sensing rateRPP, indicating the privacy protection performance of the system. Within this framework, we examine several illustrative examples, validated through numerical simulations.

In comparison with upper-layer authentication mechanisms, the tag-based Physical-Layer Authentication (PLA) attracts many research interests because of high security and low complexity. This paper mainly concerns two problems in prior tag-based PLA schemes, where the first one is extra overhead and vulnerability due to the reason that the parameter is broadcasted and the other one is the problem of setting the parameter empirically. Therefore, two new tag-based PLA schemes are proposed to address the above limitations. Specifically, a blind tag-based PLA scheme (BTP) is presented to achieve accurate authentication without knowing the tag parameter of the legitimate transmitter, which not only saves the communication overhead but also improves security. Then, an adaptive blind tag-based PLA scheme (ABTP) is further proposed, which adaptively sets the tag parameter according to the wireless channel state to achieve a better balance among robustness, security, and compatibility. Rigorous theoretical analyses are provided for the two proposed schemes and the prior schemes’ performance comparisons are given. The accuracy of the theoretical analyses is verified through simulation results. At last, the advantages and disadvantages of the two proposed schemes are discussed, and suggestions are given according to different scenarios.

This paper concerns the problem of authenticating different transmitters at the physical layer in a multi-user scenario. In this paper, we propose two tag-based Physical-Layer Authentication (PLA) schemes in a multi-user scenario. We name the first scheme as the Multi-User Physical Layer Authentication and Classification (MU-PLAC) scheme, which not only detects an impersonation attack but also achieves multi-user classification. For further improving the performance of the MU-PLAC scheme for a two-user scenario, we propose an enhanced version of the MU-PLAC scheme by elaborately designing the tags of two legitimate users. We name the second scheme as the Enhanced Multi-User Physical Layer Authentication and Classification (EMU-PLAC) scheme. We provide the theoretical analysis of the proposed schemes over wireless fading channels and derive their closed-form expressions. We implement the proposed schemes and conduct extensive performance comparisons. Our simulation results show that, for a two-user scenario, the EMU-PLAC scheme provides better classification accuracy and authentication accuracy as compared with the MU-PLAC scheme.

This paper concerns the problem of improving compatibility in the tag-based Physical-Layer Authentication (PLA) without sacrificing robustness of the PLA schemes. The prior PLA schemes for improving compatibility often sacrifice robustness or introduce extra communication overhead and security vulnerabilities. The main objective of our approach is to reduce the modification ratio of the source message given the tag length via an encoding approach. Based on a tag-encoding function, we propose two encoded tag-based schemes for the scenario of a single block and the scenario of multiple blocks, respectively, which are named as the Encoded Tag-based PLA scheme for Single Block (ET-SB) and the Encoded Tag-based PLA scheme for Multiple Blocks (ET-MB), respectively. We theoretically analyze the performance of the proposed schemes over fading channels and derive the closed-form expressions of the performance analyses. We implement the proposed schemes and conduct extensive performance comparisons through simulations. Our simulation results show that the closed-form expressions of the theoretical results of the proposed schemes perfectly match the corresponding simulation results. When the SNR is 10 dB, the compatibility of the ET-SB and ET-MB schemes improves to 15.63% and 23.45%, respectively, compared to the prior scheme.