A Channel Frequency Response-Based Secret Key Generation Scheme in In-band Full-duplex MIMO Systems

In this paper, we study the benefits of in-band full-duplex (IBFD) and multi-input multi-output (MIMO) systems on the physical layer-based secret key generation (PHY-SKG) scheme. The secret key capacity (SKC) of a channel frequency response (CFR)-based PHY-SKG scheme in IBFD-MIMO systems is derived with practical imperfections and compared to its half-duplex (HD) counterpart. The results demonstrate that IBFD benefits the SKC over HD in two aspects: 1) simultaneous measurements; 2) more resources for probing to reduce errors. However, the benefits are compromised by the overheads and imperfections of self-interference cancellation (SIC). MIMO systems can significantly improve the SKC, while enlarged antenna arrays result in increased probing errors. Besides, longer overheads will be required to implement effective SIC, decreasing the IBFD gain over HD. 3GPP specification-based simulations verify the theoretical analysis.