Channel-Based Authentication Game in MIMO Systems

In this paper, we investigate the PHY-layer authentication that exploits the spatial decorrelation property of radio channel information to detect spoofing attacks in multiple-input multiple-output (MIMO) systems. We formulate the interactions between a receiver that applies the PHY-layer MIMO authentication technique and a spoofing node as a zero-sum game. In this game, the receiver chooses the test threshold of the hypothesis test of the PHY-layer authentication to maximize its utility based on the Bayesian risk in the spoofing detection. The adversary chooses its attack frequency, i.e., how often a spoofing packet is sent over multiple antennas. The unique Nash equilibrium of the static MIMO authentication game is derived and the condition for its existence is presented regarding the number of antennas. We also investigate the dynamic authentication game, and propose a PHY-layer MIMO authentication based on Q-learning to achieve the optimal test threshold in the spoofing detection via trials, and implement it over universal software radio peripherals. The performance of the spoofing detection algorithm is evaluated via experiments in indoor environments.