The fifth generation (5G) wireless networks are on the way to be deployed around the world. The 5G technologies target to support diverse vertical applications by connecting heterogeneous devices and machines with drastic improvements in terms of high quality of service, increased network capacity and enhanced system throughput. However, 5G systems still remain a number of security challenges that have been mentioned by researchers and organizations, including decentralization, transparency, risks of data interoperability, and network privacy vulnerabilities. Furthermore, the conventional techniques may not be sufficient to deal with the security requirements of 5G. As 5G is generally deployed in heterogeneous networks with massive ubiquitous devices, it is quite necessary to provide secure and decentralized solutions. Motivated from these facts, in this paper we provide a state-of-the-art survey on the integration of blockchain with 5G networks and beyond. In this detailed survey, our primary focus is on the extensive discussions on the potential of blockchain for enabling key 5G technologies, including cloud computing, edge computing, Network Function Virtualization, Network Slicing, and D2D communications. We then explore and analyse the opportunities that blockchain potentially empowers important 5G services, ranging from spectrum management, data sharing, network virtualization, resource management to interference management, federated learning, privacy and security provision. The recent advances in the applications of blockchain in 5G Internet of Things are also surveyed in a wide range of popular use-case domains, such as smart healthcare, smart city, smart transportation, smart grid and UAVs. The main findings derived from the comprehensive survey on the cooperated blockchain-5G networks and services are then summarized, and possible research challenges with open issues are also identified. Lastly, we complete this survey by shedding new light on future directions of research on this newly emerging area.

Introduction

The fifth generation 5G technology, referred to as beyond 2020 communications systems, represents the next important phase of the global telecommunication evolution, with recent successful deployments in several areas across almost all the continents1 . The 5G cellular networks are characterized by three major features supporting for Enhanced Mobile Broadband, Massive Machine Type Communication and the provisioning of Ultra-reliable Low Latency Communication services [1]. Here, the definition of 5G networks refers to the 5G cellular networks that has been empowered by the evolution of cellular technology over the long history, from 1G cellular networks to 4G cellular networks [2]. Driven by the explosion of smart mobile devices and the rapid advances of communication technologies, 5G could be a technical enabler for a plethora of new innovative business opportunities and industrial applications, and facilitates the seamless collaboration across domains by interconnecting billions of devices. The 5G cellular networks promise to revolutionize global industries and provide immediate impacts on customers and business stakeholders. The main vision of future 5G services is to provide a customized and advanced user-centric value, enabling human interconnection to meet the ever growing demands of user traffic and emerging services. To achieve these objectives, according to [2], [3], [4], several underlying wireless technologies have been proposed to enable 5G cellular networks, including cloud computing, edge computing, Network communication. Function Virtualization (NFV), Network Slicing, and D2D. However, the rapid surge and breakneck expansion of 5G wireless services also pose new security challenges such as network reliability, data immutability, privacy that must be considered and solved before wide deployments.