Efficient Kalman Modeling of Multipath Wireless Channel for Secret Key Generation

This paper establishes the applicability of observable block companion form linear Kalman innovation models, for secret key generation between communicating parties (Alice and Bob) in a multipath wireless channel. First, Kalman models are identified to describe the dynamics of the channel between both users, based on real measurements of the Received Signal Strength Indicator (RSSI) corresponding to various blocks of information. Afterwards, it was verified that the innovation errors exhibited a significant randomness content, and that there was high correlation between the parameters of Alice and Bob for the same block. In addition, improved values of maximum channel capacity for secret key generation were obtained. Additional features that make innovation Kalman models an excellent alternative for secret key generation include: simplicity of implementation, high computational efficiency, excellent performance in modeling time-varying systems, and they do not require to estimate the properties of the noise.