The fifth generation mobile communication technology (English: 5th generation mobile networks or 5th generation wireless systems, 5th-generation, 5G or 5G technology) is the latest generation of cellular mobile communication technology, namely 4G (LTE-A, WiMax), 3G ( Extensions after UMTS, LTE) and 2G (GSM) systems. 5G's performance goals are high data rates, reduced latency, energy savings, reduced costs, increased system capacity and large-scale device connectivity. The first phase of the 5G specification in Release-15 was designed to accommodate early commercial deployments. The second phase of Release-16 will be completed in April 2020 and will be submitted to the International Telecommunication Union (ITU) as a candidate for IMT-2020 technology [1]. The ITU IMT-2020 specification requires speeds of up to 20 Gbit/s for wide channel bandwidth and high capacity MIMO.

Development Background
In recent years, the fifth generation mobile communication system 5G has become a hot topic in the communication industry and academia. There are two main drivers for the development of 5G. On the one hand, 4G, a fourth-generation mobile communication system represented by long-term evolution technology, has been fully commercialized, and the discussion of next-generation technologies has been put on the agenda. On the other hand, the demand for mobile data has exploded, and existing mobile communication systems are difficult to meet the future. Demand, urgent need to develop a new generation of 5G systems.

The development of 5G also comes from the growing demand for mobile data. With the development of mobile Internet, more and more devices are connected to mobile networks, and new services and applications are emerging. Global mobile broadband users are expected to reach 9 billion in 2018. By 2020, the capacity of mobile communication networks is expected. The current network capacity has increased by 1000 times. The skyrocketing mobile data traffic will pose serious challenges to the network. First, according to the current development of mobile communication networks, it is difficult to support the growth of thousands of times of traffic, and network energy consumption and bit cost are unbearable. Secondly, traffic growth will inevitably lead to further demand for spectrum, while mobile communication spectrum is scarce, and available spectrum is presented. Large-span, fragmented distribution makes it difficult to achieve efficient use of spectrum; in addition, to improve network capacity, it is necessary to intelligently and efficiently utilize network resources, such as intelligent optimization for business and user personality, but this is not enough; finally, the future network It must be a heterogeneous mobile network with multiple networks coexisting. To improve network capacity, it is necessary to solve the problem of efficiently managing each network, simplifying interoperability, and enhancing user experience. In order to solve the above challenges and meet the growing demand for mobile traffic, there is an urgent need to develop a new generation of 5G mobile communication networks.

Basic Concepts
5G mobile networks Like the early 2G, 3G and 4G mobile networks, 5G networks are digital cellular networks in which the service area covered by the provider is divided into a number of small geographic areas called cells. The analog signals representing the sound and image are digitized in the handset, converted by the analog to digital converter and transmitted as a bit stream. All 5G wireless devices in the cell communicate with local antenna arrays and low power automatic transceivers (transmitters and receivers) in the cell via radio waves. The transceiver allocates channels from a common frequency pool that can be reused in geographically separated cells. The local antenna is connected to the telephone network and the Internet via a high bandwidth fiber or wireless backhaul connection. As with existing handsets, when a user traverses from one cell to another, their mobile device will automatically "switch" to the antenna in the new cell.

The main advantage of 5G networks is that the data transmission rate is much higher than the previous cellular network, up to 10Gbit/s, which is faster than the current wired Internet and 100 times faster than the previous 4G LTE cellular network. Another advantage is lower network latency (faster response time), less than 1 millisecond, and 4G is 30-70 milliseconds. Due to faster data transmission, 5G networks will not only serve mobile phones, but will also become a general home and office network provider, competing with cable network providers. Previous cellular networks provided low data rate Internet access for mobile phones, but a cell phone tower could not economically provide enough bandwidth as a general Internet provider for home computers.