Semantic Communication Empowered 6G Networks: Techniques, Applications, and Challenges

With the explosion of intelligent network applications and the prosperity of artificial intelligence (AI) technologies, the sixth generation (6G) wireless networks are not only expected to further improve network capacity, but also anticipated to establish a new architecture of “Intelligent Connectivity of Everything”. Semantic communication (SC) is a promising solution for future 6G networks due to its natural capability of integrating application requirements and information meaning into data transmission processes. In this paper, a comprehensive survey that overviews how SC can be applied for 6G networks and the key technologies of SC is presented. For this purpose, we first provide a detailed overview of the concepts of semantic information (SI) and SC, as well as the classifications of SC. Then, we present the vision of mutual support between SC technologies and 6G networks, as well as the potential benefits using SC for 6G applications. To achieve the benefits of SC, the fundamental theories and four important technologies in SC are thoroughly investigated, which are SC system architecture design, SI extraction, SI transmission, and SC performance evaluation. Then, we introduce open problems and potential research directions pertaining to SC. In a nutshell, this paper provides a holistic review of concepts, applications, fundamentals, key technologies, existing challenges, and open issues of SC tailored to the requirements of 6G networks.