Distributed SIMO Physical Layer Authentication: Performance Bounds Under Optimal Attacker Strategies

We provide worst-case bounds for the detection performance of a physical layer authentication scheme where authentication is based on channel-state information (CSI) observed at multiple distributed remote radio-heads (RRHs). The bounds are established based on two physical-layer attack strategies that a sophisticated attacker can launch against a given deployment. First, we consider a power manipulation attack, in which a single-antenna attacker adopts optimal transmit power and phase, and derive an approximation for the missed detection probability that is applicable for both statistical and perfect CSI knowledge at the attacker. Secondly, we characterize the spatial attack position that maximizes the attacker's success probability under strong line-of-sight conditions. We use this to provide a heuristic truncated search algorithm that efficiently finds the optimal attack position, and hence, constitutes a powerful tool for planning, analyzing, and optimizing deployments. Interestingly, our results show that there is only a small gap between the detection performance under a power manipulation attack based on statistical respectively perfect CSI knowledge, which significantly strengthens the relevance and applicability of our results in real-world scenarios. Furthermore, our results illustrate the benefits of the distributed approach by showing that the worst-case bounds can be reduced by 4 orders of magnitude without increasing the total number of antennas.Comment: Submitted to IEEE Transactions on Wireless Communication