# Results and Achievements of the ALLIANCE Project: New Network Solutions for 5G and Beyond
## 1 Introduction  
In recent years, the 5G paradigm has been gaining momentum with many global research and development (R&D) initiatives launched in major economies worldwide. Referring in particular to Europe, 5G has been recognised as the key enabler for the digitisation of the European economy [1]. Although the current and future 5G applications are countless, many of them share one thing in common. To provide a good user experience is no longer enough to provide high bandwidth alone but there is a strong requirement to increase other eight technical parameters [2], ranging from area traffic capacity (an increase of 100\(\times\) per squared-km) to network energy efficiency (100\(\times\) more efficient). As the commercial rollout of 5G continues in many countries around the world, now is the ideal moment to identify attractive subjects and research lines for the next decade, which will set the groundwork for B5G system. Network infrastructure in this 5G/B5G era needs to go well beyond the evolution of today's transport networks and must be properly designed to support end-to-end sophisticated vertical applications as envisaged by the 5G Infrastructure Public-Private Partnership (5G PPP) initiative [3]. In particular, 5G/B5G promises to focus on three outstanding features not seriously considered in the previous generations, namely large-scale machine type communication, ultra-reliable low-latency service and enhanced mobile broadband. In summary, 5G/B5G must deliver not only a better performing network, but also one that can become an infrastructure capable of supporting ubiquitous services, while at the same time meeting the performance and commercial requirements of multiple stakeholders. The research community is therefore pursuing new models to alleviate the scalability issue of the current client-server architecture while meeting the strict requirements imposed by 5G/B5G. For instance, solutions such as edge computing, fog computing, cloudlets, server mesh, etc., are currently gaining momentum to this end, with SDN/NFV providing the framework to effectively control and manage the distribution of functions across network levels. Nonetheless, these developments considerably increase the complexity in networking as well as in networked applications, fueling therefore the need for improved network automation. AI approaches--in particular those based on Machine Learning (ML) techniques--are today considered the key drivers to keep network operations simpler, smarter, safer, and speedier. In this direction, in 2018 we started a 45-month Spanish project called Architecting a knowledge-defined 5G/B5G-enabled network infrastructure toward the upcoming digital society (ALLIANCE) where several researchers with different backgrounds and skills (e.g., physical layer experts, ML experts, protocol designers, data science specialists, etc.) have collaborated with the aim of investigating novel network solutions for 5G/B5G. Now that the ALLIANCE project is approaching its end, in this paper we present an overview of our research activities. Section 2 is hence focused on presenting the ALLIANCE network architecture and its principal building components as well as summarising the main results and achievements compared with the state of the art. Each one of these components has been selected and included in the ALLIANCE architecture for specific reasons explained below. One of the ambitious goals of the ALLIANCE proposal has been the design and development of the KDN framework, implementing AI/ML techniques. Section 3 is hence dedicated to describing this KDN framework, present our practical ML-based solution for the routing problem and demonstrate its ability of supporting optimal end-to-end service provisioning. In Section 4, we introduce the novel network-monitoring element designed in ALLIANCE based on a combination of Deep Packet Inspection (DPI) and ML.