Effectiveness-Oriented SAGSIN: Unveiling a Unified Metric and a Comprehensive Framework

The space-air-ground-sea integrated network (SAGSIN) has emerged as a consensus from both industry and academia to provide seamless coverage and ubiquitous connectivity in the upcoming sixth generation networks, which can facilitate various remote mission-critical applications. However, the quality of service (QoS) satisfaction of mission-critical applications is significantly undermined by the adverse impacts resulting from the inherent characteristics of SAGSIN, including large scale, high dynamics, low computing and caching capability, and limited perception and communication. These characteristics severely deteriorate the timeliness and ultimate effectiveness performance of mission-critical applications in SAGSIN. In this article, we present an effectiveness-oriented SAGSIN which lays particular emphasis on the timeliness/effectiveness performance in order to ensure QoS demands of mission-critical applications. We review classic performance metrics, and then propose a new metric, named synchronization cost of information (SCoI) that directly describes the effectiveness of mission-critical applications. To effectively support mission-critical applications, we propose a joint perception-communication-computing-actuation (JPCCA) framework that adapts to the time-varying network environment. A case study on object detection and tracking in SAGSIN demonstrates the superiority of the proposed metric and framework as compared to baseline schemes. Finally, we point out the open issues on effectiveness-oriented SAGSIN implementation.