Secret key agreement based on a communication through wireless MIMO fading channels

The method of key sharing between a mobile unit and a base station through a wireless MIMO-based fading channel is investigated. The description of a key distribution protocol is given. The expression to estimate the correct key bit agreement based on the use of guard interval is proved. Statistical properties of the key string are tested using the NIST criteria. Impossibility of key string eavesdropping by illegal users is guaranteed due to small values of correlation between legal and eavesdropper carrier phases. Numerical examples show that the MIMO system with 8 antennas is able to agree 256 bits with a reliability value 0.99 for SNR equal to 35 dB. This experiment confirms that the MIMO scenario is especially effective for secret key distribution.