Performance Analysis of One- and Two-way DV-QKD with MIMO FSO Communication Systems

TL;DR

This paper analyzes the performance of one- and two-way DV-QKD protocols in MIMO FSO systems, deriving new expressions for key rate and error rate, and assessing the impact of MIMO configurations and protocol choices on security over distance.

Contribution

It introduces novel frameworks for one- and two-way DV-QKD in MIMO FSO systems, providing analytical expressions and performance comparisons.

Findings

Larger MIMO configurations improve secret key rate.

Two-way protocols offer better performance over longer distances.

Tradeoffs exist between protocol types depending on transmission distance.

Abstract

This paper considers a multiple-input multiple-output (MIMO) wireless system wherein two legitimate users attempt to exchange secret keys over free-space optical (FSO) channels. Novel frameworks for the use of the one- and two-way discrete-variable quantum key distribution (DV-QKD) protocols, employing weak coherent pulses and decoy states, are presented. Focusing on the case where a photon-number-splitting attack is adopted by the eavesdropper and the legitimate multi-antenna receiver using threshold detection for the key extraction, novel expressions for the secret key rate and quantum bit error rate for both one- and two-way protocols are derived. The performance gain with larger MIMO configurations and the tradeoff between the performances with the one- and the two-way protocols with respect to the transmission distance of the legitimate FSO link are numerically assessed.