Impact of Channel Estimation Errors on Secret Key Capacity in MIMO-OFDM Systems

MIMO-OFDM as well as MIMO systems are two steering technologies for 5G and beyond communication systems. The key problem with conventional method is that the security protocols used does not take any advantage of the wireless channel features, making eavesdropping a serious issue. This poses security issues at the physical layer. In this paper, we use SecretKey Capacity (SKC) on MIMO and MIMO-OFDM systems with more than one receiver antennas for the eavesdropper. We investigate the impact of channel estimation errors on the SKC performance. We derive the closed form expressions for SKC for both the MIMO and MIMO-OFDM channel The effect of channel estimation errors at the legitimate receiver end is also investigated for different MIMO-OFDM configurations. MIMO-OFDM channels can achieve positive SKC even when eavesdropper has higher number of receiver antenna than legitimate receiver, which is not possible in the case of MIMO channels. Increase in the channel estimation errors can increase SKC of the system. SKC results are discussed here with different number of transmit and receive antenna for eavesdropper and legitimate receiver.