Unified 3D Networks: Dynamic RAN Functions Placement and Link Challenges

3D Network convergence across ground, air and space wireless communications holds immense promise, offering disruptive use cases and addressing the challenges of ubiquitous connectivity. Next-generation mobile networks may need to transcend the current ground-focused paradigm and fully embracing aerial and spaceborne communications becomes essential. The unified 3D network requires adaptations at the radio as well as at the network level. This paper presents an analysis of the dynamic placement of Radio Access Network (RAN) functions, exploring the specific challenges associated with the links between Distributed Units (DUs) and Radio Units (RUs), as well as between DUs and Centralized Units (CUs), within the context of 3D unified network. The dynamic placement of RAN functions introduces significant complexities, including latency management, synchronization, resource allocation, etc. The DU-RU link faces challenges such as high bandwidth requirements, real-time processing needs and efficient beamforming techniques to maintain robust connectivity. Meanwhile, the DU-CU link must address issues related to mobility, handover processes and maintaining low-latency communication despite the physical separation of network components. By analyzing these challenges, this paper provides insights into the necessary technological advancements and strategic approaches required to optimize the dynamic placement of RAN functions, ensuring the seamless operation and high performance of 6G networks.