Full-duplex Relay-assisted URLLC with Channel Estimation Error in a Factory Automation Scenario

This paper investigates the block error rate (BLER) performance and proposes an optimal power allocation scheme of a two-hop decode-and-forward full-duplex relaying system with imperfect channel estimation information in a factory automation scenario that requires ultra-reliable low-latency communication (URLLC). In the relay-assisted system, a central controller S sends signals to a remote device D with the aid of a robot R with channel estimation error (CEE). First, considering CEE at each receiver and the residual loop interference of the full-duplex relay, we derive an approximate closed-form expression of BLER under the Nakagami-m fading channel. Next, to minimize the overall BLER, we propose an optimal power allocation scheme between the controller and the robot with a total power constraint. Furthermore, we prove that BLERs of S-R and R-D links are strictly convex in terms of the transmit power of the controller. Simulation results illustrate the performance of the considered relay-assisted system and validate our theoretical analysis.