ds to be interconnected. You should walk through your Yangguan Road, and I will walk on my single-plank bridge. However, with the expansion of their respective spheres of influence, the two forces gradually penetrated and merged with each other in a new field. It is this integration that promotes the rapid development of the so-called mobile Internet. The development of the mobile terminal is a good proof of the integration of these two networks. Today's smart phones are more and more like computers, and various PADs derived from computers are more and more like mobile phones. The boundaries between them are becoming increasingly blurred.

Figure 2. The overall development trend of mobile communication systems

In fact, this so-called convergence is to a certain extent the result of the struggle between the telecommunications and computer communities. The wall that divides the interior and exterior is the initial focus of these two forces. Buildings constitute a small besieged city, and the computer network closed indoors wants to break through WiMax to the vast outdoor world. The mobile communication network, which specializes in wide-area coverage, wants to continue to conquer cities and dominate the world inside and outside. Judging from the actual situation of standardization and network deployment and application, traditional telecommunication forces represented by LTE seem to have an absolute advantage. However, this superficial advantage does not mean the failure of the computer industry. For it, it is nothing more than the need to raise milk cows in order to drink milk. In the era of mobile Internet where application is king, there is no need to squeeze our last one-third of acre in the field of pipeline laying, where telecom workers are better at making small profits.

With the popularization of smart terminals, a wide variety of applications represented by OTT have strongly squeezed out the profit space of traditional telecommunications services, leading to the transfer of profits to upper-level services and terminal areas. The application level is the traditional sphere of influence in the computer field. Also due to the substantial increase in the degree of intelligence, many application functions of the terminal have been turned to customer-oriented, instead, the communication function has gradually become a chicken rib that cannot be completely discarded. In an era where fans rely on feelings to attract users, the old communication giants in the terminal field have been beaten by companies that started with computers like Apple.

2. Internet of Things

Some people say that everything can be digitized. For the communications industry, the next sentence corresponding to it is that everything can be interconnected. Therefore, in addition to the mobile Internet, another new type of network is mainly the so-called Internet of Things, which is composed of originally independent devices all around us. If the mobile Internet is basically a human network, then the Internet of Things is a broader network that encompasses things and things, and people and things.

The industry’s vision for 5G is that with the support of these two networks, through new technologies such as cloud computing, a communication system that can realize the interconnection of all things, ubiquitous, and immersive people will be built around 2020. .

three. market trend

One of the driving forces of 5G development is the development and integration of the above-mentioned services and the emergence of new network forms. The other major driving force of 5G development, or pressure, comes from the explosive development of system scale. The system scale mentioned here includes the scale of data traffic and the scale of terminal connections.

Figure 3 shows the forecast results of my country's 5G promotion organization-IMT-2020 on the growth trend of traffic demand. Take some hot spots in Beijing (such as Xidan, Wangfujing, etc.) as an example, mobile data traffic will increase by about 1,000 times around 2020. The total amount of data traffic demand is directly related to the type of business and the number of terminals. Figure 4 firstly shows the forecast of IMT-2020 on the development trend of the number of terminal connections. The impact of service types on data traffic demand will be further analyzed in subsequent chapters.

Figure 3. IMT-2020 forecast of data traffic growth trend

Figure 4. IMT-2020 forecast of the growth trend of the number of terminal connections

According to this forecast, the number of global mobile terminals will reach 18 billion in 2030. It is worth mentioning that, as time goes by, there will be a huge leap in IoT terminal equipment relative to the population and the number of traditional mobile terminals around 2030. Figure 5 shows the ITU's forecast of the development trend of the number of mobile terminals (non-IoT terminals) and the proportion of terminal categories. It can be further seen that in these mobile terminals, the vast majority will be smart devices such as smart phones or tablet computers that rely on data to eat.

Figure 5. ITU's forecast of the development trend of the number of mobile terminals and the proportion of various types of terminals

four. Business needs

According to the discussion in Section 2, the huge data flow and the huge number of terminals will inevitably cause huge pressure on the future mobile communication system. Here, let us further explore what kind of business can lead to the explosive development of data traffic and connection demand.

1. Ultra HD, 3D video

Effectiveness and reliability are the two most basic requirements of our communication system. The so-called validity is the fidelity of information. In the process of transferring from information source to information sink, we hope that the communication system can reproduce the information source as truthfully as possible. For example, a series of concepts such as standard definition, high definition, full high definition, and ultra high definition mainly emphasize the reproduction of visual information details, pursuing a complete visual experience, and three-dimensionalization can further enhance the user's visual experience. It is conceivable that the accurate reproduction of detailed visual information will inevitably lead to a sharp increase in the amount of information and a substantial increase in the transmission rate requirements. For example, after 8K 3D video is compressed by 100 times, a transmission rate of 1Gbps is still required.

2. Immersive video/augmented reality/virtual reality

At present, people's pursuit of fidelity is mainly aimed at visual and auditory information. In fact, in our complete sensory world, it includes not only sight, hearing but also a series of perception forms such as smell, taste and touch. Moreover, if the visual information is perfectly reproduced in a way out of the matter, it is not enough to give people the so-called immersive experience. This sense of presence that can be fully reproduced is the ultimate goal pursued by augmented reality and virtual reality technologies. If you want to communicate or play online in a virtual reality, immersive experience, in addition to data rate requirements, it will also bring extreme requirements for delay control.

3. Cloud Desktop

With a powerful computing center and access to the network, many daily computer operations, including basic file storage and reading, can be performed in the cloud, which gave rise to the so-called cloud desktop concept. Based on the cloud desktop, users may only need basic I/O devices such as a monitor, keyboard, and mouse locally. In order to obtain a response time equivalent to that of local storage and reading, extremely high requirements must be imposed on the transmission rate and delay of the access network.

4. OTTOTT means over the top, and its typical representatives include Skype and WeChat. This is a type of business that operators hate. The word Over the top itself is very challenging: Whose top is over? In fact, OTT was riding on the head of the operator and asked Tai Sui to help him count the bills. Today’s operators are very similar to my country’s railway system: I paved the railway, I drove the train, and I monopolized the high-priced lunch on the car. The iron cart on the car tirelessly sells beer, beverages and mineral water at high prices. The waiter of the chicken feet instant noodles and ham sausage is also my relative. Think about it, I drove a train, took my wife out of the city, ate hot pot and sang songs, and suddenly I was robbed by a gangster. For operators, the bitterness and loss are self-evident.

These bandits climbed into the car from nowhere, shuttled among the operators' customers, and provided passengers with a variety of novel and convenient services at almost no money. This group of knights who rob the rich and help the poor make ordinary users suffering from monopoly cheer for it, but they give operators a great headache. OTT services require frequent interaction of massive small data packets, which will bring about a substantial increase in signaling overhead, thereby greatly increasing the burden on the network. In this way, OTT services not only take a big advantage, but also leave a lot of rubbish to the operation of the network. The most important thing is that the proliferation of OTT services has accelerated the transfer of profits to upper-level services other than traditional communication services, and operators have gradually reduced to low-level basic service providers such as roads, water, electricity and gas and channels for others to make profits. .

5. Business experience in extreme scenarios

Mobile communication systems such as LTE have already made some people get rich first. In areas with ideal channel conditions and high signal-to-noise ratios, higher data rates can be supported through AMC and MIMO. However, like the current situation in society, those who get rich first have absolutely no motivation to drive everyone to get rich together. The user group of the communication system is also a microcosm of society, and in such a small society, there is no need to suffer from inequality. Therefore, the imbalance of the data rate often leads to the psychological imbalance of many users, which greatly affects the user experience.

After the mobile communication system meets the basic coverage requirements, the problem of unbalanced experience has increasingly become an important direction for system improvement and optimization. Technologies such as CoMP that emphasize collaboration and collaboration are actually advancing along this line of thinking. Such problems will also become one of the important concerns of the 5G system. Specifically, the so-called extreme scenarios mainly include: application scenarios where the speed is extremely fast (such as high-speed trains or even airplanes) and users are particularly dense (such as terminal buildings, waiting rooms, concerts, sports meets, and emergencies). As shown in Figure 6, the 5G system hopes that users can feel a higher quality of service anytime and anywhere.

Figure 6. Status of business experience (left) and uniform user experience requirements (right)

6. Internet of Things business

The main application areas of the Internet of Things business cover information collection required in fields such as environmental monitoring and public safety, as well as various tasks such as information interaction and control in the fields of industry, transportation and home furnishing. An important feature of the Internet of Things business is that the business types are rich, and the specific needs of each type of business vary greatly. For example, in some extreme application scenarios, a large number of Internet of Things devices will be deployed in mountainous areas, forests, water bodies and other areas that may be very remote and the transmission environment is quite unsatisfactory, as well as indoor corners, basements, tunnels and other areas where signals are difficult to reach.

Figure 7 lists some typical IoT business applications and their specific requirements for communication systems.