Secrecy Rate of Analog Collaborative Beamforming With Virtual Antenna Array Following Spatial Random Distributions

In this letter, we propose a physical layer security technique based on analog collaborative beamforming (CB) in mobile ad hoc networks such as unmanned aerial vehicles or vehicular networks. While digital CB requires prohibitive overhead and complexity in highly mobile networks, in the proposed algorithm the nodes participating in CB, i.e., virtual antenna array (VAA), keep changing their locations and adapt their phases in a distributed way, so that the received signal is co-phased toward the receiver but randomized at the non-receiver direction. Assuming uniform distribution of CB nodes in 2-D space, we analyze the secrecy rate, considering the independent random channel gains from the CB nodes based on the communication distance. Through simulation, we observe that with a pertinent size of VAA in 2-D space, the proposed technique can provide significantly higher secrecy rate compared to the existing analog beamforming algorithm with fixed antenna locations.