Secret Key Agreement Over Multipath Channels Exploiting a   Variable-Directional Antenna
  We develop an approach of key distribution protocol (KDP) proposed recently by T. Aono et al. A more general mathematical model based on the use of Variable-Directional Antenna (VDA) under the condition of multipath wave propagation is proposed. Statistical characteristics of VDA were investigated by simulation, that allows us to specify model parameters. The security of the considered KDP is estimated in terms of Shannon's information leaking to an eavesdropper depending on the mutual locations of the legal users and the eavesdropper.   Antenna diversity is proposed as a mean to enhance the KDP security. In order to provide a better agreement of the shared keys it is investigated the use of error-correcting codes. 
Valery Korzhik, Viktor Yakovlev, Guillermo Morales-Luna, Yuri Kovajkin
cs.IT math.IT