1.1 The Background of 5G
5G is short for the fifth-generation wireless system or the fifth-generation mobile network (Hu, 2016), which applies to the next-generation mobile communication standard. In recent years, 5G has been the research and development (R&D) focus of the telecommunication industry. In 2012, some nations and areas around the world began to study the needs and technologies of 5G mobile communication technology (Du et al., 2018). Major global businesses and regions are guiding 5G development by introducing strategic planning, deploying major projects, releasing spectrum planning and other means. The standardization and commercial application of 5G is also accelerating significantly (Han et al., 2018). The general agreement is that 5G systems can be launched around 2020 (Zhang et al., 2017). 5G will be different from previous generations of communication networks. The goals of 5G include creating viable solutions for vertical industries such as the auto industry, healthcare, transportation and utilities. However, it is undeniable that after several generations of development, wireless technology has produced almost inestimable tremendous socio-economic value. 5G will be the first generation with the explicit goal of providing social and economic benefits, so many new 5G functions are expected to be implemented.
Before discussing the structure and features of the fifth-generation (5G), it would seem appropriate to clarify the need to design such a network. So it is helpful to look back at the previous generation. From Figure 1, we can know the development of 1G to 5G network, such as the general deployment date, theoretical download rate and delay time. For example, 4G, deployed in the 2010s, provides a theoretical download rate at the speed of 1Gbit/s and 60-98 ms delay (ITU, 2018). While 5G, deployed in the 2020s, affords theoretical download rate at the speed of 10Gbit/s and less than 1ms delay. 5G could theoretically offer ten times the speed of 4G, as well as millions of connections and ultra-low latency, which are fundamental to the Internet of things (IoT) (Zhang, 2019). 5G networks aim to meet various customers’ service quality requirements in different applications (Zhang et al., 2017). For example, in a place where unseamed wide-area coverage is required, the 5G network system can equip customers with high-data-rate services at all times, no matter where they are. It is broadly agreed that 5G networks should solve six problems that 4G networks have not adequately solved, such as higher capacity, higher data rates, lower end-to-end latency, large-scale device connectivity, lower costs and consistent quality of experience (Gupta and Jha, 2015).
Figure 1.
The development of wireless network
From Figure 2, the three main applications of 5G are continuous widespread coverage and high capacity scenario (eMBB), low delay and high-reliability scenario (uRLLC) and low power consumption and large connection scenario (mMTC) (Liu et al., 2018). In the 5G era, mobile communication will be improved to support IoT business fully cantered on things, people, and objects (Du et al., 2018). The pre-4G technology has created a very brilliant internet economy, While 5G technology opens another door to the industrial Internet era (Zhang, 2019).
Figure 2.
The three main application scenarios of 5G
The main business of the 5G network at the initial stage is HD and UHD video, AR/VR and cloud games, which belong to the category of eMBB scenes. The development phase will generate uRLLC scenarios, such as industrial manufacturing, autonomous driving, telemedicine and intelligent transportation. When it reaches the mature stage, it will face massive large-scale application and connection requirements of the Internet of things (Liu et al., 2018). Social progress and demand, in turn, promoted the revolution and progress of the telecommunication system (Li et al., 2014).