Key Establishment Employing Reconfigurable Antennas: Impact of Antenna Complexity

When establishing secret encryption keys using estimates of the reciprocal wireless channel, the number of key bits that can be generated for a static or slowly varying propagation environment can be enhanced by randomly changing the radiation properties of a reconfigurable antenna. However, prior studies of this approach have been limited and have not considered a high degree of antenna reconfigurability. This paper uses simulations and experimental measurements to characterize the impact of reconfigurable antenna complexity on the performance of key establishment in different static propagation environments and in the presence of a multi-antenna eavesdropper. The results demonstrate that reconfigurable antennas can significantly enhance the security, even when the eavesdropper antennas are adjacent to or surround one of the legitimate nodes. The results further demonstrate that increasing the number of reconfigurable parasitic elements notably increases the achieved performance.