Performance analysis of cellular radio access networks relying on control- and user-plane separation

In a Software-defined radio access network (SD-RAN), the control base stations (CBSs) are part of the control plane (CP) which are used for transmitting reliable control data. By contrast, the traffic base stations (TBSs) in the user plane (UP) are used for transmitting user data. Based on queuing theory and stochastic geometry, we derive the coverage probability of CP under non-line-of-sight (NLoS) transmissions, and derive the energy efficiency of UP under a two-slope path loss model, where the line-of-sight (LoS) and NLoS propagation conditions coexist. Our analytical results show that when the traffic load is high, the coverage probability of CP increases when increasing of the CBSs' service rates or the density of CBSs. We also found that the maximum energy efficiency of UP can be achieved by optimizing the TBS density, while achieving a high area spectral efficiency.