Control-Oriented Uplink and Downlink Co-Design for Low-Latency Unmanned Operations

In the upcoming sixth-generation (6G) era, the network is envisaged to support field robots for unmanned operations. With the network connections, the sensor uploads raw data to the edge platform via the uplink (UL), and the edge platform extracts task-related information and sends it to the actuator via the downlink (DL) for actions. The sensor, edge platform, and actuator form a sensing-communication-computing-control (SC<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup>) loop. This paper investigates a control task executed by the SC<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> loop. Given the low-latency requirement of the control task, we model the DL transmission in the finite block length (FBL) regime. On this basis, we propose a control-oriented uplink and downlink (UL&DL) co-design scheme, which takes the control linear quadratic regulator (LQR) cost as the objective and optimizes the UL&DL bandwidth, time, and block length. An efficient two-tier iterative algorithm is proposed to solve the mixed-integer problem. Simulation results reveal the superiority of the proposed scheme, which aligns UL&DL within the SC<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> loop to improve control performance.