Toward 6G $\text{TK}\mu$ Extreme Connectivity: Architecture, Key Technologies and Experiments.

Sixth-generation (6G) networks are evolving toward new features and order-of-magnitude enhancement of systematic performance metrics compared to the current 5G. In particular, the 6G networks are expected to achieve extreme connectivity performance with Tbps-scale data rate, Kbps/Hz-scale spectral efficiency, and $\mu\mathrm{s}$, -scale latency. To this end, an original three-layer 6G network architecture is designed to realize uniform full-spectrum cell-free radio access and provide task-centric agile proximate support for diverse applications. The designed architecture is featured by super edge node (SEN), which integrates connectivity, computing, Al, data, etc. On this basis, a technological framework of pervasive multi-level (PML) artificial intelligence (Al) is established in the centralized unit to enable task-centric near-real-time resource allocation and network automation. We then introduce a radio access network (RAN) architecture of full spectrum uniform cell-free networks, which is among the most attractive RAN candidates for 6G $\text{TK}\mu$ extreme connectivity. A few most promising key technologies, that is, cell-free massive MIMO, photonics-assisted Terahertz wireless access, and spatiotemporal two-dimensional channel coding are further discussed. A testbed is implemented and extensive trials are conducted to evaluate innovative technologies and methodologies. The proposed 6G network architecture and technological framework demonstrate exciting potentials for full-service and full-scenario applications.