Centralize or Distribute? A Techno Economic Study to Design Low Cost Edge Cloud Radio Access Network

Cloud radio access network (CRAN) has been proposed as a promising network architecture for 5G where all base band processing functions are split/decoupled from the radio unit (RU) and centralized. However, rigid bandwidth and latency requirements are incurred by fronthaul, transport link which connects RU to the central cloud. Therefore, new functional splits are discussed for a dual-site processing architecture, called Edge-CRAN (e-CRAN), where some functions remain distributed and co-located with remote sites while others are split at central site to reduce the cost of the fronthaul transport system. However, there is a trade-off between reducing the cost of fronthaul (by distributing functions) and reducing the cost of remote site (by centralizing functions). In this work, from a perspective of minimizing the total cost of ownership (TCO) for e-CRAN, we present a techno-economic study to find the optimal functional splits for a base station (BS), with given configuration. A configuration of a BS represents different radio access technologies (RATs) running in different frequency bands. For each functional split we propose a model to calculate the requirement of computational resources and fronthaul bandwidth.. We formulated a TCO minimization model using constraint programming. Numerical results show that the optimal functional split depends on BS configuration, fiber ownership and even downstream/upstream. e-CRAN can achieve lower TCO than both DRAN and CRAN with optimal functional split.