Bbu Hotelling In Centralized Radio Access Networks

This chapter focuses on the role of BBU hotelling in converged network architectures. The main motivations behind this technique are described, and the critical drawbacks are detailed, mainly related to the transport of the new "fronthaul" traffic over the network infrastructure. A classification of the various architectural solutions for BBU hotelling is detailed, regarding BBU placement and implementation, and fronthaul transport. Finally, a specific example of converged network architecture is presented, which is based on an optical WDM aggregation network supporting both fronthaul and backhaul traffic. We discuss also a novel network optimization problem, the BPTR (BBU Placement and Traffic Routing), whose objective is the minimization of a generic cost/energy metric. The problem is solved through a heuristic algorithm, and a numerical evaluation is carried on over randomly generated multi-stage aggregation networks. The main result is that the achievable BBU consolidation into a few hotel nodes is considerably high for realistic geographic scenarios, justifying the evolution toward converged networks.