IEEE Globecom Workshops (GC Wkshps)
The Optimal Preprocessing Approach for Secret Key Generation from OFDM Channel Measurements
Guyue Li, Aiqun Hu, Linning Peng, Chen K. Sun
Abstract
Physical layer secret key generation techniques have spurred much recent research interest. In general, the secret key establishment contains four main procedures: channel sounding, quantization, information reconciliation and privacy amplification. However, to overcome the non- reciprocity and correlation problems in key generation from orthogonal frequency division multiplexing (OFDM) channels, a preprocessing procedure is added to prepare inputs for quantization. This paper demonstrates the optimal preprocessing approach in secret key generation and addresses its practical problems in realization. More specifically, we first build the mathematical model of a preprocessing procedure. Then, we identify that principle component analysis (PCA) can achieve the optimal performance in this model from the perspective of secret key capacity. Next, we discuss the realization steps of PCA algorithm and the corresponding procedures to cooperate with it. The parameter design in matrix partitioning and covariance matrix calculation are also analyzed. Numerical results verify that the proposed PCA preprocessing outperforms other tall unitary transforms and thus, it can be used to generate secret key with high key generation rate (KGR), low key error rate (KER) and good randomness.