Cost-Effective Migration Toward Virtualized C-RAN With Scalable Fronthaul Design

Migration from distributed to centralized radio access networks (C-RANs) can be expensive in terms of capital expenditures due to the initial investment while it has lower operational expenditures due to pooling baseband processing into the cloud and reduced power consumption. Partial centralization can be also an option by employing network function splitting and keeping lower physical layer functions colocated with the RUs. This increases the power consumption but relaxes the high capacity requirement in the front haul. It is not intuitive which migration strategy is more cost effective. In this article, we formulate a pool placement optimization problem as an integer linear programming (ILP), which minimizes the total cost of ownership (TCO), and evaluate the migration cost to C-RAN with both full centralization of network functions, and partial centralization by using function splitting. We define a network upgrade optimization problem, by adding new cells to the network, as a revisited version of the original optimization problem to evaluate the upgradability of the architectures. We solve the problem with both ILP for optimality, and genetic algorithm for scalability. Simulation results show that partial centralization results in optimal TCO with lower crossover time compared to C-RAN with full centralization.