Internet of Things (IoT) enables physical objects to sense, communicate, and perform certain actions on demand, which can facilitate a multitude of applications, including smart home, smart city, and intelligent transportation system. Along with the advantages of IoT is the security issue. In IoT, the security threats are even extended from the cyber world to cyber-physical world. To ensure security, the typical approach is through upper-layer cryptographic algorithms/protocols. However, they heavily rely on the availability of key management system and might be comprised as the computation power of adversaries keeps increasing.

As a complement, information-theoretic security can be provided by exploiting the characteristics of the physical (PHY) layer, even though adversaries have infinite computational capabilities. With recent advances in computing, artificial intelligence, signal processing, coding, and so on, PHY security can be further enhanced to protect data and authenticate legitimate users in IoT. The purpose of this special issue is to publish original efforts describing theoretical and practical research endeavors in the domain of PHY layer security for IoT.

Potential topics include but are not limited to the following:

• Physical layer authentication for IoT
• Antijamming approaches for IoT
• Physical layer key generation for IoT
• PHY based secure communications for IoT
• Artificial intelligence aided PHY security
• Advanced signal processing for IoT security
• Lightweight PHY security and PHY location protection for IoT
• Cross-layer design for secure communications