Authentication is an important issue in wireless communications because the open nature of the wireless medium provides more security vulnerabilities. Recently, Physical-Layer Authentication (PLA) attracts many research interests because it provides information-theory security and low complexity. Although many researchers focus on the PLA and exploit its potential in enhancing wireless security, the literature is surprisingly sparse with no comprehensive overview of the state-of-the-art PLA and the key fundamentals involved. Thus, this article provides a detailed survey of features and techniques that can be used in the PLA. We categorize the existing PLA schemes into two categories: passive and active schemes. In the passive schemes, a receiver authenticates the transmitter based on the physical-layer features of the received signals. We further divide the passive schemes into two sub-categories: device-based features and channel-based features. In the active schemes, a transmitter generates a tag based on a secret key and embeds it into a source message. Then, a receiver authenticates the transmitter based on the tag whether it exists in the received signal. We further divide active schemes into two sub-categories: non-covert schemes and covert schemes. Moreover, we also provide some future research directions.

中文翻译：

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无线通信中的物理层身份验证概述

身份验证是无线通信中的一个重要问题，因为无线介质的开放性提供了更多的安全漏洞。最近，物理层身份验证（PLA）吸引了许多研究兴趣，因为它提供了信息理论上的安全性和较低的复杂性。尽管许多研究人员专注于PLA并开发其在增强无线安全性方面的潜力，但令人惊讶的是，文献稀疏，没有对最新的PLA及其所涉及的关键基础进行全面的概述。因此，本文详细介绍了可在PLA中使用的功能和技术。我们将现有的PLA方案分为两类：被动方案和主动方案。在无源方案中，接收器根据接收信号的物理层特征对发送器进行身份验证。我们将无源方案进一步分为两个子类别：基于设备的功能和基于通道的功能。在主动方案中，发送器根据秘密密钥生成标签，并将其嵌入到源消息中。然后，接收器根据标签验证发送器是否在接收信号中。我们进一步将活动方案分为两个子类别：非隐蔽方案和隐蔽方案。此外，我们还提供了一些未来的研究方向。我们进一步将活动方案分为两个子类别：非隐蔽方案和隐蔽方案。此外，我们还提供了一些未来的研究方向。我们进一步将活动方案分为两个子类别：非隐蔽方案和隐蔽方案。此外，我们还提供了一些未来的研究方向。