Joint Beamforming and Scheduling for Integrated Sensing and Communication Systems in URLLC

Abstract

Integrated Sensing and Communications (ISAC) has been regarded as a technological trend in 6G networks to obtain significant performance gain with deep integration of sensing and communication functionalities. However, achieving Ultra-Reliable and Low-Latency Communication (URLLC) with ISAC designs has been under-investigated. In this paper, we investigate a joint beamforming and scheduling design for an ISAC-enabled system fulfilling URLLC requirements. In particular, we employ an ISAC design to sense stochastic events, through which an aperiodic traffic is generated. The event-triggered aperiodic traffic is next scheduled with a periodic traffic. Meanwhile, the system provides reliability for both periodic and aperiodic traffics within a hard latency constraint. To understand the latency and reliability performance under the joint design, we first describe the sensing and communication processes under a Partially Observable Markov Decision Process (POMDP) framework. Then, we analytically express the two traffics' latency and reliability performance under the joint beamforming and scheduling. Based on the analysis, we formulate an optimal tradeoff between the performance of the periodic and aperiodic traffics, and obtain it by a Dynamic Programming (DP)-based algorithm. Simulation results finally show that the optimal tradeoff outperforms other tradeoffs of benchmark algorithms.