Towards an Effective Secret Key Generation Scheme for Imperfect Channel State Information

This paper concerns on inefficiency or even failure in secret key generation caused by the imperfect channel state information. We propose a secret key generation scheme based on wavelet analysis. Firstly, the channel estimates are pre-processed by wavelet analysis to improve the correlation. Secondly, to ensure the randomness of the secret keys, an adaptive equal probability quantization approach is proposed to quantize the estimates. Then, the quantized preliminary keys are reconciled and their privacy is amplified to obtain a final secure key. Furthermore, we validate the feasibility of the proposed scheme in real environments. Simulation and testing results all show that the proposed scheme achieves remarkable improvement in terms of bit mismatch rate and key generation rate compared with existing schemes. Besides, for the randomness, the generated keys pass the National Institute of Standards and Technology (NIST) test.