Modern communication network Technology series Click to view Chapter 2 Click to view Chapter 3 5G NR standard: Next Generation Wireless communication Technology 5G NR: The Next Generation Wireless Access Technologyeric Darman (Erik Dahlman) [Sweden] Stefan Barker (Stefan Parkvall), John schelder (Johan Sk? ld) Zhu Huaisong Wang Jian Liu Yang translation
5G overview over the past 40 years, the world has witnessed the development of four generations of mobile communication systems. The first generation of Mobile communication started around 1980, using analog transmission. The main technologies include AMPS(Advanced Mobile Phone System, Advanced Mobile Phone System) formulated by North America, the NMT(Nordic Mobile Telephony, Nordic Mobile phone) jointly formulated by the public telephone network operators in northern European countries (controlled by the government at that time) and TACS(Total Access Communication System, total Access Communication System). The mobile communication system based on the first generation technology is limited to providing voice services, but this is the first time in history that mobile phones can be used by ordinary people. The second generation of mobile communication appeared in the early 1990 s, which is characterized by the introduction of digital transmission in wireless links. Although its target service is still voice, digital transmission enables the second generation of mobile communication systems to provide limited data services. At first, there were several different second generation technologies, including GSM(Global System for Mobile communication, Global Mobile communication System), D-AMPS(Digital AMPS, Digital Advanced Mobile Phone System) jointly formulated by many EU countries, PDC(Personal Digital Cellular, Personal Digital Cellular) proposed by Japan and used only in Japan, and CDMA-based IS-95 technology developed later. With the passage of time, GSM has expanded from Europe to the world and gradually become the absolute dominant technology in the second generation. Just because of the success of GSM, the second generation system changed the mobile phone from a niche product to a communication tool used by most people in the world and became a part of the necessities of life. Even today, although the third and fourth generation technologies have come out, GSM still plays a major role in many parts of the world, and in some cases it is even the only available mobile communication technology. The third generation of mobile communication, commonly known as 3G, appeared in the early 2000. 3G is a real step towards high-quality mobile broadband, especially with the help of HSPA(High Speed Packet Access, High-Speed data Packet Access) technology called 3G evolution, the rapid Access of wireless Internet is possible. In addition, compared with the early mobile communication technology based on Frequency Division Duplex (Frequency-Division Duplex,FDD) symmetric spectrum (I .e., network-to-terminal and terminal-to-network links use different spectrum respectively, see Chapter 7),3G introduces the mobile communication technology of asymmetric spectrum for the first Time, which is based on the Time Division Duplex technology based on Time Division Duplex (TD-SCDMA, TDD) promoted by China. From the past few years to the present, the fourth generation mobile communication, which is dominated by LTE technology . Based on HSPA, LTE provides higher efficiency and enhanced mobile broadband experience, that is, higher data rate for end users. This depends on OFDM-based transmission technology that can provide greater transmission bandwidth and more advanced multi-antenna technology. In addition, compared with the wireless access technology (TD-SCDMA) that 3G supports a special asymmetric spectrum operation, LTE supports FDD and TDD operation in a general wireless access technology, that is, the work of symmetric and asymmetric spectrum. In this way, LTE has realized a globally unified mobile communication technology, which is suitable for symmetric and asymmetric spectrum and all mobile network operators. In chapter 4, we will also discuss in detail how LTE evolution extends the scope of mobile communication networks to unauthorized spectrum. Figure 1-1 shows the development history of the mobile communication system.
1.1 Standardization of 3GPP and mobile communication
the key to the success of mobile communication is the existence of technical specifications and standards recognized by many countries. These specifications and standards ensure the separability and interoperability of terminals and equipment produced by different manufacturers, as well as the availability of terminals worldwide. As mentioned before, the first generation of NMT technology was jointly formulated by many countries, so that terminals and their contracted use can work effectively in these Nordic countries. The following GSM mobile communication technical specifications and standards are also formulated jointly by many European countries. The related work was carried out in CEPT, which was later renamed ETSI(European Telecommunications Standards Institute, European Telecommunications Standards organization). Therefore, from the very beginning, GSM terminals and signing services can work normally in many countries, covering a large number of potential users. This huge common market has a great demand for terminals, which has given birth to various mobile phone brands and greatly reduced the price of terminals. However, with the formulation of 3G technical specifications, especially WCDMA, a real global mobile communication standard has been developed. At the beginning, the formulation of 3G technical standards was also based on regions in Europe (ETSI), North America (TIA,T1P1), Japan (ARIB) and other places. However, the success of GSM has shown the importance of technology coverage breadth, especially in terms of terminal universality and cost. Moreover, it is increasingly clear that although different regional standardization organizations are doing their own work separately, the research technologies have many similarities. Especially Europe and Japan are studying different but very similar WCDMA(Wideband CDMA, broadband CDMA) technology. Finally, in 1998, various regional standardization organizations came together and established 3GPP(Third-Generation Partnership Project, Third Generation partner Project), whose goal was to complete the formulation of 3G technical specifications based on WCDMA. Later, a parallel organization (3GPP2) was established, whose task was to formulate the alternative technology of 3G technology -- cdma2000, as the evolution of the second generation IS-95. The two organizations (3GPP and 3GPP2) with their own 3G technologies (WCDMA and cdma2000) coexisted for many years. However, with the passage of time, 3GPP completely dominated and further extended to the formulation of 4G and 5G technologies, although the name remained 3GPP. Today, 3GPP is the only important organization in the world to formulate mobile communication technical specifications.
1.2 next generation wireless access technology -5g/NR
discussions on 5G mobile communications began around 2012. In many discussions, the term 5G refers to a specific and new 5G wireless access technology. However, 5G is often used in a broader context, which means a large number of predictable new application services that mobile communications can support in the future.
1.2.1 5G application scenarios
when it comes to 5G, three application scenarios are usually mentioned: enhanced mobile broadband communication (eMBB), large-scale machine type communication (mMTC), and ultra-reliable low latency communication (URLLC). (See Figure 1-2).
- eMBB generally refers to the direct evolution of today's mobile broadband services. It supports greater data traffic and further enhanced user experience, such as higher end-user data rates.
- mMTC refers to services that support a large number of terminals, such as remote sensors, manipulators, and equipment monitoring. The key requirements of this kind of service include: very low terminal cost, very low terminal energy consumption, and ultra-long terminal battery usage time (at least several years). Generally, each terminal of this type consumes and generates a relatively small amount of data, so it does not need to support high data rates.
- URLLC services require very low latency and high reliability. Such service instances include traffic safety, automatic control, and factory automation.
It should be pointed out that the classification of 5G application scenarios into these three different categories is artificial to some extent. The main purpose is to simplify the requirement definition of technical specifications. In practice, many application scenarios cannot be accurately classified into these three categories. For example, there may be services that require high reliability but do not require high latency. Other application scenarios may require a low cost of the terminal, but do not require a very long service life of the battery.
1.2.2 Evolution from LTE to 5G
the first version of LTE technical specifications was proposed in 2009. After that, LTE continues to evolve to provide enhanced performance and scalability. This includes the enhancement of mobile broadband, support for higher actual achievable end-user data rate and higher spectral efficiency. It also includes extended LTE application scenarios, especially supporting low-cost terminals equipped with ultra-long batteries, similar to large-scale MTC Applications. Recently, LTE has also made important progress in reducing air delay. Through these completed, ongoing, and future evolution, LTE will support many 5G application scenarios. From a broader perspective, 5G is not a specific wireless access technology, but defined by supported application scenarios, therefore, LTE should be regarded as an important part of the entire 5G wireless access solution, as shown in Figure 1-3. Although explaining LTE evolution is not the main purpose of this book, chapter 4 will give an overview of the current status of LTE evolution.
1.2.3 NR -- new 5G wireless access technology
although LTE is a powerful technology, some requirements of 5G cannot be met by LTE and its evolution. In fact, LTE started more than ten years ago, and many more advanced technologies have emerged in the past ten years. In order to meet these needs and give full play to the potential of New technologies, 3GPP began to formulate a New wireless access technology called NR(New Radio, New air interface). A seminar held in the autumn of 2015 determined the scope of NR, and specific technical work began in the spring of 2016. The first version of the NR standard was completed at the end of 2017 to meet the business needs of 5G early deployment in 2018. NR borrowed many structures and functions of LTE. However, as a new wireless access technology, NR does not need to consider backward compatibility like LTE evolution. The demand for NR is also more and wider than that for LTE, so the technical solutions will be different. Chapter 2 discusses the standardization activities related to NR. Chapter 3 is an overview of the spectrum. A brief description of LTE and its evolution is in Chapter 4. The main part of this book (Chapters 5~19) provides a detailed description of the current NR Technical Standard Status. Chapter 20 is a prospect for the future development of NR.
1.2.4 5GCN -- new 5G core network
in addition to defining NR, a new 5G wireless access technology, 3GPP also defines a new 5G core network called 5GCN. The new 5G wireless access will connect to 5GCN. However, 5GCN can also provide connectivity for LTE evolution. At the same time, when NR and LTE operate in the so-called non-standalone mode, NR can also be connected to the traditional EPC core network, which will be further described in chapter 6.