Interdependent Cell-free and Cellular Networks: Thinking the Role of Cell-free Architecture for 6G

The emerging cell-free network architecture can handle the intensified inter-cell interference in cellular networks via dynamic user-centric cooperation among multiple access points (APs), and thus is widely regarded as the fundamental architecture for 6G. However, this vision is hard to achieve in a short period due to the prohibitive expense of large-scale AP deployment and management. In this paper, we revisit the role of cell-free network architecture by comparing it with cellular architecture from both macroscopic and microcosmic perspectives. With their pros and cons in mind, we propose an interdependent cellular and cell-free network (ICCN) architecture that integrates the advantages of both. Three interdependent relationships between high-layer cellular network and low-layer cell-free network are introduced, with corresponding key enabling technologies being deeply investigated. Finally, some open issues and future research directions are also summarized and discussed.