Tutorial-Cum-Survey on Semantic and Goal- Oriented Communication: Research Landscape, Challenges, and Future Directions

SemCom and goal-oriented SemCom are designed to transmit only semantically-relevant information and hence help to minimize power usage, bandwidth consumption, and transmission delay. Consequently, SemCom and goal-oriented SemCom embody a paradigm shift that can change the status quo that wireless connectivity is an opaque data pipe carrying messages whose context-dependent meaning and effectiveness have been ignored. On the other hand, 6G is critical for the materialization of major SemCom use cases (e.g., machine-to-machine SemCom) and major goal-oriented SemCom use cases (e.g., autonomous transportation). The paradigms of \textit{6G for (goal-oriented) SemCom} and \textit{(goal-oriented) SemCom for 6G} call for the tighter integration and marriage of 6G, SemCom, and goal-oriented SemCom. To facilitate this integration and marriage of 6G, SemCom, and goal-oriented SemCom, this comprehensive tutorial-cum-survey paper first explains the fundamentals of semantics and semantic information, semantic representation, theories of semantic information, and definitions of semantic entropy. It then builds on this understanding and details the state-of-the-art research landscape of SemCom and goal-oriented SemCom in terms of their respective algorithmic, theoretical, and realization research frontiers. This paper also exposes the fundamental and major challenges of SemCom and goal-oriented SemCom, and proposes novel future research directions for them in terms of their aforementioned research frontiers. By presenting novel future research directions for SemCom and goal-oriented SemCom along with their corresponding fundamental and major challenges, this tutorial-cum-survey article duly stimulates major streams of research on SemCom and goal-oriented SemCom theory, algorithm, and implementation for 6G and beyond.