Radio-over-Fiber (RoF) for mobile backhauling: A technical and economic comparison between analog and digitized RoF

The massive deployment of new generation mobile handsets (tablets, smartphones) generates a rapid traffic growth in radio-mobile networks. Providing ubiquitous high capacity wireless links to mobile users remains today a technological and economic challenge. According to the state of the technology, the most efficient way to increase the capacity of radio-mobile networks consists in reducing drastically the size of each cell. Such an approach has a strong economic impact for radio-mobile operators. Radio-over-Fiber (RoF) techniques are considered today as a very promising solution to this problem. They consist in decoupling physically radio signal processing equipment from the antennas' sites to one or several remote locations upper in the mobile backhaul where can be placed the radio controllers. It becomes then possible to create farms of remote mobile base stations for which costly devices like radio-frequency (RF) oscillators can be pooled between multiple cells. Two generations of RoF techniques must be distinguished: Analog-RoF (A-RoF) whose feasibility has been demonstrated since the year 90s by means of multiple testbeds and Digitized-RoF (D-RoF) developed around the year 2000 exploiting the robustness of digital transmission links between the remote base stations and the antennas. The aim of this paper is to provide a quantitative comparison between A-RoF and D-RoF in terms of deployment cost (CAPEX) and energy consumption (OPEX) under various traffic growth assumptions.