# Blockchain for Future Wireless Networks: A Decade Survey
## 2 Background
### Security in Wireless Networks (From 4G to 6G)
#### 2.2.1 Security in 4G  
To mitigate the issues of a 3G network, the 4G network has been launched, which is a packet-switched network with a network capacity of at least ten times 3G network. It provides higher bandwidth, up to 100 Mbps, and service personalization to meet the demands of diverse users to provide highly customized services. The 4G network has high usability and global coverage that fulfills the users anytime and anywhere [35]. Nevertheless, the 4G technologies appear much more promising for QoS and user experience; some shortcomings still need to be addressed, such as network security and privacy. Worldwide interoperability for microwave access (WiMAX) is a well-known standard for 4G-based wireless broadband communication (IEEE 802.16). It uses orthogonal frequency division multiplexing (OFDM) and the space-time block coding (STBC) model with cryptographic encryption to secure over-the-air communication [36]. However, despite having a secure and robust WiMAX architecture, it still does not ensure end-to-end security against numerous attacks such as key exchange and management, DoS, scrambling, and masquerading  
Figure 3: Design factors of wireless networks security.  
attacks. Similar to WiMAX, long-term evolution (LTE) is another standard that enables user equipment (UE), such as laptops and smartphones, to connect to the base 4G-based base station via an evolved-universal terrestrial radio access network (E-UTRAN). The security architecture of a 4G LTE system is continually evolving and improving by incorporating secure signaling between user devices and the BS, strong authentication, and key agreement protocols [37]. However, restraining attacks at different levels of open system interconnection (OSI) is challenging and has always been a matter of concern in the 4G system. Moreover, maintaining high-level security by monitoring, analyzing, and troubleshooting makes the recurring cost more expensive. This is because more and more people are adopting smart devices for various services, such as commercial banking, mobile web access, IP telephony, video conferencing, and many more in highly insecure environments, such as wireless hotspots and public Wi-Fi (such as cafes), etc. Deploying the above-mentioned security schemes over such places is deceptive, as the 4G network is an IP-based network that is open to several vulnerabilities that invite security risks and threats associated with different 4G-based services [38].  
To overcome the aforementioned security threats, the scientific community has proposed different security solutions. For example, [PERSON] et al. [39] discussed the structure and advantages of the 4G network in wireless communication. They identify WN security problems and present secure communication solutions for 4G. Moreover, [PERSON]. [40] analyzed security and privacy issues in 4G-LTE and IoT networks. For that, they explored a DoS attack using open-source identity-defined radio (SDR). After analyzing security issues, they proposed security solutions for future WNs. [PERSON] et al. [41] analyzed various encryption algorithms, such as ZUC, SNOW 3G (a stream cipher algorithm), and advanced encryption standard (AES), that provide robust security in 4G systems. In addition, they presented cryptanalysis techniques that improve data security. However, there is a need for an upgraded technology that not only provides seamless data rates, but also protects from modern vulnerabilities and security threats. Therefore, a 5G-based wireless communication is proposed, which is discussed in the following topic.