PlaceRAN: Optimal Placement of Virtualized Network Functions in the Next-generation Radio Access Networks

The fifth-generation mobile evolution introduces Next-Generation Radio Access Networks (NG-RAN), splitting the RAN protocol stack into the eight disaggregated options combined into three network units, i.e., Central, Distributed, and Radio. NG-RAN enables the management of network units and the protocols disaggregated as radio functions. These functions' placement is challenging since the best decision is based on the RAN protocol stack split, routing paths of transport networks with restricted bandwidth and latency requirements, different topologies and link capabilities, asymmetric computational resources, etc. This article proposes the first exact model for the placement optimization of radio functions for NG-RAN planning, named PlaceRAN. The main objective is to minimize the computing resources and maximize the aggregation of radio functions. The PlaceRAN evaluation considered two real network topologies based on 5G-crosshaul and Passion European projects. Our results show that the PlaceRAN model achieves an optimal high-performance aggregation level. Moreover, we prove that PlaceRAN is flexible for RAN deployment overcoming the network restrictions. Therefore, PlaceRAN is the most innovative approach to provide advanced NG-RAN design and development.