D-RAN is the traditional RAN or Radio Access Network where BBU (Baseband Unit) and RRH (Remote Radio Head) are placed on the same place in the site.
C-RAN is the decoupling between BBU and RRH, Where BBU is moved to the data center to be centralized to manage different RRHs through Fronthaul Common Public Radio Interface (CPRI).
This results in a fronthaul transport network between the RRU and the centralized BBUs that will then be virtualized, using Commercial-Off-The-Shelf (COTS) servers. The BBU itself will be further disaggregated into a Centralized Unit (CU) and Distributed Unit (DU), which results in a midhaul transport network between them. By converging 4G/5G fronthaul, 5G midhaul, and 4G/5G backhaul, network infrastructure cost, and complexity are optimized.
- C-RAN enables significant reductions in power consumption, footprint, and complexity deployed at 4G/5G cell sites.
- The Common Public Radio Interface (CPRI) for 4G LTE C-RAN is highly inefficient and won’t scale cost-effectively from a fronthaul bandwidth perspective.
- For 5G NR RAN, available capacity will be significantly higher than 4G LTE, particularly with High Order Multiple-Input Multiple-Output (MIMO) antenna deployments.
- Several sub-layers of the 5G NR RAN functions will be decomposed and virtualized over x86 COTS servers, which will have a major impact on the required xHaul network performance to deliver upon the full promise of 5G.