Channel covariance matrix based secret key generation for low‐power terminals in frequency division duplex systems

The existing secret key generation (SKG) techniques are not applicable for frequency division duplex (FDD) Internet of Things networks due to the low power constraints and limited computing resources. This letter proposes a SKG scheme based on the channel covariance matrix in FDD systems. First of all, a novel algorithm is proposed for inferring the downlink channel covariance matrix from the observed uplink channel covariance matrix with the aid of the transformation matrix. Then, a complete SKG scheme for low‐power terminals in FDD systems is designed to generate keys from the downlink channel covariance matrix. Finally, simulation results show that this scheme can generate high‐agreement secret keys in FDD systems. Compared with the loopback mechanism‐based SKG scheme, this scheme is suitable for low‐power terminals and can achieve significant performance improvement in terms of the key disagreement ratio.