  Fog radio access network (F-RAN) and virtualisation are promising
technologies for 5G networks. In F-RAN, the fog and cloud computing are
integrated where the conventional C-RAN functions are diverged to the edge
devices of radio access networks. F-RAN is adopted to mitigate the burden of
front-haul and improve the end to end (E2E) latency. On other hand,
virtualization and network function virtualization (NFV) are IT techniques that
aim to convert the functions from hardware to software based functions. Many
merits could be brought by the employment of NFV in mobile networks including a
high degree of reliability, flexibility and energy efficiency. In this paper, a
virtualization framework is introduced for F-RAN to improve the energy
efficiency in 5G networks. In this framework, a gigabit passive optical network
(GPON) is leveraged as a backbone network for the proposed F-RAN architecture
where it connects several evolved nodes B (eNodeBs) via fibre cables. The
energy-efficiency of the proposed F-RAN architecture has been investigated and
compared with the conventional C-RAN architecture in two different scenarios
using mixed integer linear programming (MILP) models. The MILP results indicate
that on average a 30% power saving can be achieved by the F-RAN architecture
compared with the C-RAN architecture.
