The impact of array mutual coupling on propagation-based key establishment

Theoretical analyses and practical protocol implementations have demonstrated the concept of using reciprocal electromagnetic propagation as a basis for establishing secret encryption keys that enable secure communication between two radios. Recent studies have extended this concept, demonstrating that when multiple-antenna radios are used for such key establishment, the key rate, or the number of bits that can be generated for each channel estimate, can be increased (C. Chen and M. A. Jensen, IEEE Trans. Mobile Computing, 10, 205-215, 2011). However, these prior studies have largely ignored the impact of antenna mutual coupling on the achievable key establishment performance.