Wireless communication security: physical-layer techniques exploiting radio and propagation characteristics

The increasing popularity of wireless data transfer means that the volume of sensitive data communicated over wireless networks is rapidly increasing. Because of the inherent vulnerabilities associated with wireless data transmission, significant recent attention has focused on increasing communication security. While most commonly, this security is accomplished at the higher layers of the protocol stack, recent research has demonstrated that certain features of the radio antennas and hardware as well as the properties of the electromagnetic propagation can be exploited to enhance transmission security. The resulting physical-layer techniques offer advantages that are not achievable with traditional protocols and algorithms at the higher layers. As a result, coupling these physical-layer techniques with more conventional protocols leads to enhanced communication security. We discuss two different areas in which such physical-layer approaches are useful.