AN also provides advantages in controlling ongoing opera- tional costs, improving network security, network controllability, network agility, and flexi- bility. The application of the C-RAN concept to small-cell architectures provides capacity benefits beyond those achieved through cell virtualization. In a traditional small-cell archi- tecture, each access point provides a fixed amount of capacity within its coverage area. This might work well only if the user traffic is evenly distributed across the coverage area, a con- dition that is rarely happens in real life. The result is that some access points will be over- loaded and others are relatively idle across time. Unlike stand-alone small cells where the addition of the new cells further aggravates the inter-cell interference, C-RAN architectures can be expanded and scaled. 1.1.6.1 Architectural Aspects Cloud-based processing techniques can be implemented to centralize the baseband proces- sing of multiple small cells and to improve inter-cell mobility and interference management. Small cells can support a variety of applications and services including voice-over-IP and videoconferencing, which can greatly benefit from a centralized architecture. C-RAN archi- tecture comprises distributed RRHs commonly connected to centralized BBUs using optical transport or Ethernet links. The RRHs typically include the radio, the associated RF ampli- fiers/filters/mixers, and the antenna. The centralized BBU is implemented separately and performs the signal processing functionalities of the RAN protocols. The centralized BBU model enables faster service delivery, cost savings, and improved coordination of radio capabilities across a set of RRHs. Fig. 1.23 shows the migration from distributed RAN architecture to the centralized model. In a V-RAN architecture, the BBU functionalities and services are virtualized in the form of VMs running on general-purpose processor platforms that are located in a centralized BBU pool in the CO that can effectively manage on- demand resource 