Joint Scheduling and Power Control for Predictable Per-Packet Reliability in URLLC

5G-and-beyond cellular networks are set to enable ultra-reliable, low-latency communications (URLLC), catering to a wide range of applications such as real-time control and extended reality (XR). For these URLLC applications, it is crucial to ensure per-packet communication reliability and high throughput. To this end, we propose a novel joint scheduling and power control approach, denoted by PktR, that ensures application-specific per-packet communication reliability as well as high channel spatial reuse and high network throughput. PktR is designed as a close-loop system, incorporating Gain-Ratio-K (GRK) interference modeling, optimization, and transmit power control mechanisms. PktR ensures predictable interference control for receivers and fine-tunes transmit power at transmitters in a highly agile manner. Our measurement studies demonstrate for the first time the feasibility of ensuring per-packet communication reliability in live cellular systems, by showing that PktR ensures high per-packet communication SINR (e.g., 20dB) and high success probability (e.g., 0.9) across diverse network and environmental settings. Through local, distributed coordination, PktR also outperforms state-of-the-art solutions significantly. For instance, besides ensuring predictable guarantee of required per-packet communication reliability in scenarios where existing solutions are unable to provide such guarantees for up to 31.01 % of the network links, PktR improves the network throughput by a factor up to 1.596.