  Current Distributed Radio Access Networks~(D-RANs), which are characterized
by a static configuration and deployment of Base Stations~(BSs), have exposed
their limitations in handling the temporal and geographical fluctuations of
capacity demands. At the same time, each BS's spectrum and computing resources
are only used by the active users in the cell range, causing idle BSs in some
areas/times and overloaded BSs in other areas/times. Recently, Cloud Radio
Access Network~(C-RAN) has been introduced as a new centralized paradigm for
wireless cellular networks in which---through virtualization---the BSs are
physically decoupled into Virtual Base Stations~(VBSs) and Remote Radio
Heads~(RRHs). In this paper, a novel elastic framework aimed at fully
exploiting the potential of C-RAN is proposed, which is able to adapt to the
fluctuation in capacity demand while at the same time maximizing the energy
efficiency and resource utilization. Simulation and testbed experiment results
are presented to illustrate the performance gains of the proposed elastic
solution against the current static deployment.
