1 Optical systems enabling 5

Photonic technologies are largely used in optical communication systems and networks due to their unique characteristics in term of bandwidth, immunity to electromagnetic fields, compatibility with the optical fiber and flexibility. The possibility to fabricate photonic devices through CMOS compatible processes paves the way for low cost and reduced footprint circuits making optical technologies available for any network segments and new applications. Here the importance of Photonics for 5G development and deployment is addressed together with some technological alternatives and perspectives. 1 Optical systems enabling 5G Antonella Bogoni Scuola Superiore Sant’Anna Pisa Luca Potì Photonic Networks & Tecnhologies Nat’l Lab – CNIT, Pisa Giancarlo Prati Photonic Networks & Tecnhologies Nat’l Lab – CNIT, Pisa IRCPhoNeT, Pisa Marco Romagnoli Photonic Networks & Tecnhologies Nat’l Lab – CNIT, Pisa 268 A. Bogoni, L. Potì, G. Prati, M. Romagnoli The rising penetration of smart connected devices, promising compelling services anywhere and anytime, is having a huge impact on the mobile broadband infrastructure and on the ability to provide a quality experience to the final users, whether humans or connected things. The new 5G radio access ecosystem, expected by 2020 [1], will have to sustain an average traffic increase of one order of magnitude and peak rates up to three orders of magnitude higher than the current ones [2]. Many time sensitive services will also demand extremely low transmission latency. Radio technologies will evolve by allocating new bands (beyond 10 GHz), by leveraging higher-order multiple-input multiple-output (MIMO), carrier aggregation, and beam forming techniques. In parallel, the transport network for backhaul (BH) and fronthaul (FH) applications will demand support of higher capacities to increase the number of transport clients, to support a wider range of performance requirements, and to provide increased flexibility. This must be achieved in a cost-effective and sustainable manner. Based on the radio architectures, it is possible to define many deployment scenarios, ranging from the fully centralized one, i.e., the cloud radio access network (CRAN), to the conventional scenario, in which all functions are replicated at each radio site with monolithic radio base stations (RBSs). Moreover, as envisioned in [3], novel radio-splitting models are under development to meet 5G high-bandwidth demands, leveraging different distributions of radio functions between radio unit nodes and centralized processing nodes. Realistic scenarios will see a mix of all mentioned radio architectures, with a combination of traffic types to be transported among the radio devices. If mobile as communication was conceived for humans (mobile broadband and media delivery), 5G will include also machine type communication between devices (sensors, actuators etc.) that must communicate with the same wireless access technology. A vast variety of use cases are predicted for 2020 each with very different connectivity requirements: from the broadband access in a dense area or in a crowd, monitoring and automation of infrastructures and buildings, remote controlled heavy machines, control in real time of remote machines, intelligent transportation system, communication with high user mobility (500 Km/h), etc. as shown in Fig. 1.