# Leveraging Blockchain Technology for Secure 5G Offloading Processes +
## 1 Introduction
* Signal interference: 5G signals, especially in the higher frequency bands, are more susceptible to interference from physical obstacles such as buildings, trees, and other urban elements in the city, resulting in shadow areas where coverage is poor or non-existent. * Upgrade costs: Extending an existing 5G network is costly, as it requires the installation of new base stations and antennas, and can be prohibitive for some cities. * Regulations: Installing a new 5G infrastructure (base stations or antennas) requires obtaining permits and complying with local regulations. This process can be slow and bureaucratic, delaying the expansion of 5G. * Coverage disparity: In many cities, 5G coverage is unequal, with central and busy areas receiving better coverage than peripheral or less populated ones. * Environmental impact: The installation of additional base stations may raise concerns about the environmental impact on cities. In this context, offloading-based solutions have already proven to be useful to improve the coverage and efficiency of 5G networks. Offloading refers to the process of transferring data traffic from a core 5G network to alternative networks, such as those from other operators, or Wi-Fi solutions, to provide more robust and cost-effective connectivity. The main advantages of using offloading techniques in 5G are as follows [10; 11]:* Improved Coverage: In areas where the 5G signal is weak, intermittent, or inexistent, offloading to other networks provides an additional reliable connection. * Congestion Reduction: By diverting some traffic to alternative networks, the load on the core 5G network is reduced, improving the quality of service. * Resource Optimization: Offloading allows for better utilization of available resources, as alternative networks can handle the additional traffic without negatively impacting the core network. * Cost Savings: For network operators, offloading can be a more cost-effective way to manage data, as it avoids the need to invest in additional 5G infrastructure. * Flexibility and Scalability: Offloading offers a flexible and scalable solution for managing data traffic in dynamic urban environments, adapting to changing network needs. Although offloading techniques have already been extensively investigated in the literature [12; 13], there are still some security risks that need to be addressed in order to have a fully secure offloading process. It is currently difficult to guarantee that only authorized users and devices access alternative networks within an offloading process, avoiding Man-in-the-Middle (MitM) attacks [14]. In addition, data exchanged during the offloading process must be trustworthy, unchanged, and private, especially in critical applications such as public safety [15]. For this reason, this paper proposes a novel offloading architecture for 5G systems in which authentication and privacy are enhanced by leveraging Blockchain technology in two different ways: (i) using a permissioned Blockchain network as a secure and private marketplace for available communications resources; and (ii) using Self Sovereign Identity (SSI) as a novel authentication solution in 5G offloading environments. This paper is organized as follows: Section 2 discusses the state-of-the-art about security in the 5G offloading processes with a focus on operators marketplaces and authentication systems; Section 3 describes the proposed Blockchain-based secure 5G offloading mechanisms based on a Blockchain-based marketplace described in Section 3.1 and an SSI-based authentication system described in Section 3.2. Section 4 presents the increments in the offloading times due to both security solutions. Finally, Section 5 explains the main conclusions of the work.