Since Shannon's pioneering masterpiece which established the prototype of modern information theory, the goal of communications has long been promising accurate message reconstruction at a refined bit-by-bit level, which deliberately neglects the semantics/effectiveness aspect of information. Nevertheless, the recent development of wireless technologies and the spurt of deep learning (DL) techniques allow us to reclaim the meaning/usefulness aspect in the design of future 6G communication paradigms, where goal-oriented communication is becoming a trend. Age of Information (AoI), a well-known metric that captures the importance of information by recording the time elapsed from the generation time slot, has been extended to various variants, such as Value of Information (VoI), Urgency of Information (UoI), Age of Incorrect Information (AoII), and etc. While each of them proposes novel ways to measure the meaning/usefulness aspect of information, there is not yet an integrated framework encompassing all of them. To this end, we propose a novel tensor-based approach, the Goal-oriented Tensor (GoT), to unify them, which also allows more flexible and fine-grained goal characterizations. Following the proposed GoT, we architect a holistic goal-oriented framework to enable goal-oriented semantic communications, in which information perception, dissemination, and control-plane decisions are implemented in accordance with specific goals. Finally, we outline several open challenges to fulfill the vision of the GoT framework.

翻译：自香农开创性著作奠定现代信息理论基础以来，通信的目标长期致力于在逐比特精细层面上实现准确的消息重建，这刻意忽略了信息的语义/效用层面。然而，无线技术的近期发展及深度学习技术的突飞猛进，使我们能够在未来6G通信范式的设计中重新审视信息的意义/有用性层面，其中目标导向的通信正成为一种趋势。信息年龄（AoI）——这一通过记录自生成时刻起的时间流逝来捕捉信息重要性的知名指标——已被扩展为多种变体，如信息价值（VoI）、信息紧急度（UoI）、错误信息年龄（AoII）等。尽管每种变体都提出了衡量信息意义/有用性层面的新方法，但目前尚缺乏一个涵盖所有变体的统一框架。为此，我们提出了一种新颖的基于张量的方法——目标导向张量（GoT）——以实现统一，该方法还允许更灵活、更精细的目标表征。遵循所提出的GoT，我们构建了一个整体的目标导向框架，以支持目标导向的语义通信，其中信息感知、传播与控制平面决策均根据特定目标来实施。最后，我们概述了实现GoT框架愿景所面临的几项开放挑战。