# Optical Technology for NFV Converged Networks
## 1 Introduction  
5G and its evolutions enable new use cases such as industrial automation, mission critical Internet of Things (IoT), and advanced consumer services like virtual reality, augmented reality, and gaming with outstanding user experience. These new use cases will create additional revenue streams for Communication Service Providers. However, these new services require an adaptation of the network and its operations. In order to provide a good level of connectivity everywhere and among every point, the traditional network segments are evolving towards \"one network\" where the mobile infrastructure will be able to support any service, including enterprises, and the fixed infrastructure will evolve to also support mobile traffic. Such a new network segment where 5G mobile transport, fixed access, and vertical services converge is often referred to as Xhaul [1,2]. To comply with low latency use cases, some mobile core network functions need to move to the access. Traditional big data centers, in regional network segments, will be replaced by smaller ones, located closer to the antenna sites. Moreover, the transport network is evolving, replacing point to point physical connections, common in the access area, with rings, tree o simple mesh transport networks. The mobile core network is evolving as well, becoming cloud native to allow new services to be created faster and in a more agile way. However, while some networkfunctions will run on generic processors, other functions will remain implemented on dedicated hardware and managed as regular physical network functions (PNF). In addition to 5G and IoT, other technologies, such as the Software Defined Networking (SDN) and Network Function Virtualization (NFV), will contribute to deeply transform the business of new digitalized industries. SDN facilitates the management and configuration by applying the software approach in all network operations. NFV allows to decouple the network functions from the proprietary hardware appliance, by using functions as Virtual Machines (VMs). Moreover, NFV uses Information Technology (IT) to partition the networks into virtualized building blocks that link up to produce communication services. As soon as industries introduce virtualized and software-defined infrastructure to expand their business in the digital economy, network automation will become essential to re-scale and re-purpose their operations. The concept of \"one network\" targets End-to-End (E2E) network management, encompassing the entire network: radio, transport, and cloud resources. The access network segment will require not only higher bandwidth and lower latency than today, but also a higher level of automation, comparable with that of the other segments. Today optical communication technology can meet in principle high bandwidth and low latency requirements, however an enhanced level of automation is needed to enable the realization of networks that are managed E2E automatically as \"one network\". Moreover, just scaling down in performance and cost the optical technology used in today metro and aggregation networks could be insufficient, since the capillary distributed terminations of the new access network will demand much smaller equipment size, energy consumption, and cost. Silicon photonics are promising for this purpose, but they have been utilized, so far, mainly for datacom applications, e.g., to provide internal high bandwidth connectivity in data centers, that present different requirements with respect to telecom applications. Achieving a high level of automation at a suitable cost and size is one of these requirements. There are promising research results addressing this aspect [1] but not yet large-scale industrial investments. In this paper, we will discuss the new transport requirements in the access network, focusing on an implementation based on integrated silicon photonics.