The next wave of innovation will certainly generate numerous new opportunities for emerging technology solutions based on networking services and applications with stringent key performance indicators (KPIs) such as ultra-low 1 ms latency, a 1000 fold bandwidth increase, 99.99 % reliability and availability, which are immensely above those supported by current mobile networks. A new architecture of mobile networking called cloud radio access network (C-RAN) has been introduced over the last few years not only to supporting these indicators, but also to increasing scalability, manageability, and flexibility of mobile systems. In this context, this paper addresses the principal technology enablers and their features for C-RAN fronthaul architectures of the 5 th generation (5G) mobile networks, namely space-division multiplexing (SDM), massive multiple-input multiple-output (MIMO) signaling, analog radio-over-fiver (A-RoF), and millimeter wave (mmWave) frequency technology. These technologies pave the way towards a truly viable and efficient fronthaul infrastructure for 5G mobile communications with connectivity for thousands of users and strict latency control. In this fashion, we perceive a network infrastructure scenario with seamless starting and ending interfaces by exploiting space diversity in both radio frequency and optical domains with efficient integrated photonics technology-all combined with adaptive softwaredefined network programming, so as to satisfy the 5G KPIs. Furthermore, we address the most relevant features of these technologies as a potential guideline for potential fronthaul infrastructure deployment of next generation mobile networks.