Date Added: May 2011
The authors study the non-coherent capacity of secret-key agreement with public discussion over i.i.d. Rayleigh Fading wireless channels, where neither the sender nor the receivers have access to instantaneous Channel State Information (CSI). They present two results. At high Signal-to-Noise Ratio (SNR), the secret-key capacity is bounded in SNR, regardless of the number of antennas at each terminal. Second, for a system with a single antenna at both the legitimate and the eavesdropper terminals and an arbitrary number of transmit antennas, the secret-key capacity-achieving input distribution is discrete, with a finite number of mass points.