Authentication scheme for mobile OFDM based on security information technology of physical layer over time-variant and multipath fading channels

Abstract

This work investigates security information technologies for wireless mobile environment. Traditionally, security is viewed as an independent feature addressed above the physical layer (PHY). All widely used cryptographic protocols are established assuming the PHY layer is merely used to provide an error-free link. However, with the emergence of ad hoc and decentralized networks, higher-layer security techniques are complex and hard to be implemented. To complement and enhance traditional security mechanism, we study a novel authentication scheme for mobile orthogonal frequency division multiplexing (OFDM) based on the channel power-delay profile (PDP),1The PDP is interchangeable with the channel-tap power in this study.1 considering channel time and frequency selectivities. More specifically, the PHY layer, employing the properties of OFDM signals over time-variant and multipath fading channels, is aimed to assist the overall authentication process. To identify different transmitters (TXs), we employ the hypothesis test based on their PDPs to distinguish different transmission terminals. It is advantageous to use the PDP as the wireless signature, because it depends on the surrounding environment and is therefore considered to be very hard to mimic. The proposed PDP estimation is obtained based on the redundancy of cyclic prefix (CP), which is a common feature for almost all OFDM systems. The performance is analyzed, and simulations confirm the advantages of the proposed method.