Secret Key Agreement for Massive MIMO Systems with Two-Way Training under Pilot Contamination Attack

Abstract

This work presents a secret key agreement (SKA) protocol for a multiuser time-division duplex cellular system under an active eavesdropping called pilot contamination attack (PCA) when the base station (BS) is equipped with a large antenna array. In particular, we study how to incorporate twoway training, i.e. conducting training processes in both the uplink and down-link transmissions, into the SKA protocol for the purpose of strengthening the protocol against the PCA and/or improving secret key generation efficiency. It will be shown that the two-way training provides the SKA protocol with a considerable enhencement of estimation for eavesdropper's channel. Secrecy performances of the proposed SKA protocol is quantitatively analyzed in terms of secrecy outage probability and average secret key rate, which shows that the two-way training improves the security performances especially in fast fading environments.