Planning of 5G C-RAN with Optical Fronthaul: A Scalability Analysis of an ILP Model

We focus on cross-layer optimization of 5G radio-optical communication networks (5G-RONs) that implement a centralized/cloud radio access network (C-RAN) architecture with the optical fronthaul network assuring the connectivity between remote radio heads (RRHs) and centralized base-band units (BBUs). In particular, we study a 5G-RON planning problem, which concerns cost-effective placement of RRHs, BBUs, and optical fibers, with the requirement to achieve certain level of population coverage. The problem is formulated as an integer linear programming (ILP) problem. The main goal of this work is to assess the difficulty of practical solving ILP models in 5G-RONs scenarios. Our scalability analysis of ILP modeling is performed in terms of different network dimensions, various RRH coverage radius, as well as under consideration of problem extensions related to signal latency requirements. The obtained numerical results indicate on the complexity of solving the ILP model even for moderate size networks, and motivate for further studies in 5G-RON optimization.