pproach, the densification of access nodes can be realized in a distributed manner through deployment of small cells (e.g., pico-cells or femto-cells) or via a centralized scheme using distributed antenna system (DAS) 32 in the form of C-RAN archi- tecture. In small-cell networks, femtocells are typically installed by the subscribers to improve the coverage and capacity in residential areas, and the pico-cells are installed by the operators in hotspots. Thus, in small-cell networks the coordination mechanism is often distributed. Compared to relays, DAS transmits the user signals to the base station via fiber links, while the relays use the wireless spectrum either in the form of in-band or out-of- band. 1.1.6 Cloud-RAN and Virtual-RAN Operators in quest of more efficient ways to accommodate the increasing use of smart- phones and other heavy data-consuming wireless devices in their networks face a dilemma when it comes to expanding network capacity and coverage. Optical fiber is typically the first option which is considered when addressing the problem of exponential traffic growth in the network. However, optical fiber is expensive; it takes a long time to install; and in some locations, it cannot be installed. To improve the network capacity and cover- age, operators have several options among them small cells, carrier Wi-Fi, and DASs. These and a host of other solutions are being used by network operators as methods of expanding their network to accommodate the exponential user traffic and new applications. A distributed antenna system is a network of spatially separated antennas which are connected to a common source via a transport mechanism that provides wireless service within a geographic area or structure. Distributed antenna system improves mobile broadband coverage and reliability in areas with heavy traffic and enhances network capacity, alleviating pressure on wireless networks when a large group of people in close proximity are actively using their terminals. Distributed antenna system is an approa