Cellular Mobile Communication (CMCC) uses cellular wireless networking to connect terminals and network equipment through wireless channels, thereby enabling users to communicate with each other during activities. Its main feature is the mobility of the terminal, and it has cross-zone switching and automatic roaming across the local network.
Cellular mobile communication services refer to voice, data, video images, and other services provided through a cellular mobile communication network consisting of equipment such as base station subsystems and mobile switching subsystems.
The rapid development of network communication The overall measure presents diversification, has a high and relatively open advantage, and to a large extent can meet the conditions of people’s life and production in the Internet era. The development of various industries in the current society is relatively rapid, and the demand for mobile communication is also developing and expanding, and the role is getting bigger.
But the power of a single base station is actually very small. Seemingly a complex behemoth, it can only cover a radius of a few hundred meters. In dense urban areas, a 4G base station in the 1800 MHz band covers a radius of about 300 meters.
Therefore, one isolated base station alone cannot provide good service, and many base stations need to join together, follow the same rules, and work together to meet mobile communication needs. This large number of base stations combined with some other transmission, control nodes, to form a network. The industry generally calls this network a cellular mobile communication network.
History of cellular mobile communication development
1G
In 1978, Bell Labs developed the Advanced Mobile Phone Service (AMPS) system, which is the first true sense of a high-capacity cellular mobile communication system with the ability to communicate anywhere, anytime.
AMPS uses frequency multiplexing technology to ensure that mobile terminals are automatically connected to the public telephone network throughout the service coverage area, with greater capacity and better voice quality, which is a good solution to the contradiction between the high-capacity requirements and spectrum resource limitations faced by public mobile communication systems.
In the late 1970s, the United States began large-scale deployment of AMPS systems, AMPS with excellent network performance and quality of service has won the praise of the majority of users. the rapid development of AMPS in the United States has promoted the research of cellular mobile communications technology in the world.
By the mid-1980s, Europe and Japan had also established their own cellular mobile communication networks, mainly including the ETACS system in the UK, the NMT-450 system in Northern Europe, and the NTT/JTACS/NTACS system in Japan. These systems are analog frequency division duplex (FDD) systems, also known as the first generation of cellular mobile communication systems or 1G systems.
2G
900/1800MHz GSM mobile communications
900/1800MHz GSM second-generation digital cellular mobile communications (GSM mobile communications) services are voice and data services provided by GSM mobile communications networks operating in the 900/1800MHz frequency band, and the GSM mobile communications system uses TDMA technology for the radio interface and MAP protocol for the core network mobility management protocol.
The 900/1800MHz GSM second-generation digital cellular mobile communication services include the following main types of services.
End-to-end two-way voice services.
Mobile messaging services, using the GSM network and messaging platform to provide mobile station-initiated, mobile station-received messaging services.
Mobile bearer services and mobile data services on them.
Mobile supplementary services, such as caller number display, call forwarding services, etc.
Mobile smart network services are provided through GSM network and smart network together, such as prepaid services, etc.
China domestic roaming and international roaming services.
900/1800MHz GSM The operator of the second-generation digital cellular mobile communication service must set up its own GSM mobile communication network, and the type of mobile communication service provided may be part or all of it.
Providing mobile communications services through the network can be the same operator’s network, but also by different operators of the network together. To provide international communication services on mobile networks, international communication entrances, and exits must be established through state approval.
800MHz CDMA mobile communication
The 800MHz CDMA second-generation digital cellular mobile communication (CDMA mobile communication) service refers to the voice and data services provided by the CDMA mobile communication network operating in the 800MHz frequency band, which adopts narrowband code division multiple access CDMA technology for the radio interface and IS-41 protocol for the core network mobility management.
The 800MHz CDMA second-generation digital cellular mobile communications services include the following main types of services.
End-to-end two-way voice services.
Mobile messaging services are initiated by mobile stations and received by mobile stations using CDMA networks and messaging platforms.
Mobile bearer services and mobile data services on them.
Mobile supplementary services, such as caller number display, call forwarding services, etc.
Mobile smart network services are provided through CDMA network and smart network together, such as prepaid services, etc.
China domestic roaming and international roaming services.
800MHz CDMA The operator of the second-generation digital cellular mobile communication service must set up its own CDMA mobile communication network, and the type of mobile communication service provided may be part or all of it. The network through which the mobile communication services are provided at one time can be the network of the same operator or the networks of different operators together.
3G
Third-generation digital cellular mobile communications (3G mobile communications for short) services refer to voice, data, video images, and other services provided using third-generation mobile communications networks.
The main feature of the third-generation digital cellular mobile communication service is that it can provide mobile broadband multimedia services, which support 144kb/s rate in a high-speed mobile environment, 384kb/s rate in walking and slow mobile environment, 2Mb/s rate data transmission in an indoor environment, and ensure high reliable quality of service (QoS).
The third-generation digital cellular mobile communications services include all the types of services and mobile multimedia services available in the second-generation cellular mobile communications.
Operators of third-generation digital cellular mobile services must set up their own 3G mobile networks, and the type of mobile services provided can be part or all of the end-to-end services. Providing a mobile communication service through the network can be the same operator network facilities, but also by the network facilities of different operators together. The provision of international communication services must pass through a state-approved and established international communication entrance and exit.
4G
Although the 3G system solved the drawbacks of 1G and 2G system, its actual speed is far from the expected value, then the international organizations 3GPP and 3GPP2 started a new round of 3G evolution plan, among many candidate standards LTE stood out, at the end of 2004, the 3GPP organization launched the LTE plan, the plan to achieve a smooth transition from 3G to 4G, so LTE is also also known as the quasi-4G standard.
The ultimate goal of the plan is to provide a low-latency, high-throughput, large-scale coverage wireless communication network. LTE has two working modes, FDD and TDD, among which LTE-TDD has China’s independent intellectual property rights and was commercialized in China at the end of 2013, and its high-speed bandwidth capacity brings a new experience for users. More than 4 million LTE base stations have been deployed worldwide, and this number is expected to grow with future development.
5G
Cellular networks have been built over the years and have become the foundation of mobile communications, with extensive coverage and secure and reliable communications. According to Qualcomm, global IoT connections will exceed 5 billion by 2025.
From smart wearable devices to smart water and electricity meters, from smart manhole covers to car terminals, it will cover all aspects of smart cities, smart transportation, environmental monitoring, and healthcare. A large number of smart terminals will be connected to the network, and the cellular network will become the main bearing network of IoT.
With the diversification of IoT, access methods, and the development of fog computing, edge computing, and cloud computing, the architecture of cellular IoT for the 5G network is becoming clear. The network architecture separates the transport layer from the edge resource layer and decouples the application layer from the service management layer.
The sensing layer is the entry point of information, through various sensors and embedded controllers, the collected parameters are sunk into the sensing layer through various communication methods, such as ZigBee, Bluetooth, WiFi, Lora, etc. The sensing layer is the front end of the whole architecture, and all data information is generated through this layer, which is the infrastructure of the architecture.
The transport layer is responsible for data transmission. 5G terminals, NB-IoT terminals, and eMTC terminals are all classified in this layer. Another important component of the transport layer is the 5G IoT gateway, which is responsible for protocol conversion and transmission, converting various communication methods (ZigBee, Bluetooth, WiFi, Lora, etc.) in the sensing layer to 5G communication-compatible data formats.
The main function of the edge computing layer is device access and data processing. Edge computing terminals mostly use embedded terminals, which can effectively share and reduce the core network overhead through edge computing, and the core network only needs to process the data after edge computing, which greatly improves the network performance. This layer also involves security, authentication, and identification functions.
Fog computing connects the cloud computing layer and provides a seamless connection between the IoT edge computing layer and public and private clouds, including interface definition, permission management, resource management, and function definition.
The cloud computing layer includes both public and private clouds and is the sink for all data. A large amount of data is stored and calculated in the cloud data center to provide services for upper-layer applications.
The highest layer of the architecture is the application layer, and the ultimate purpose of all layers in the architecture is to serve this layer by processing big data to support applications such as artificial intelligence, decision support, and vehicle networks.
Categories of cellular mobile communications
Traditionally, Europe uses the 900 MHz band while North America uses the 800 MHz bands. Most Asian countries use both bands. The main analog standard for the 900MHz allocated frequency in Europe is the full access communication system, although some European countries use other standards GSM is a digital system in the 900MHz band that has been adopted as a common standard in Europe and used in many other countries around the world, providing a very useful roaming device.
In addition, the GSM standard has been used for 1800 MHz (DCS 1800). Some countries are setting up independent 1800 MHz networks while others are trying to increase their GSM capacity with this band.
Because the same protocol is used in both bands, it is increasingly common to use the terms GSM-900 and GSM-1800 instead of GSM and DCS 1800.
Common cellular mobile communication systems can be divided into three categories according to their function, macrocells, microcells, and smart cells, and each of these three cellular technologies usually has its own characteristics.
Macrocell
In a cellular mobile communication system, in the early stage of network operation, the main goal of operators is to build large macro cellular cells to obtain the largest possible geographical coverage. The coverage radius of each cell of macrocellular is mostly 1km to 25km, and the antennas of base stations are made as high as possible. Within the actual macro cellular small, there are usually two special tiny areas.
One is the blind spot, a shadow area caused by the radio waves encountering obstacles during propagation, and the communication quality in this area is seriously poor.
The second is the hot spot, a busy business area formed due to the uneven distribution of spatial service load, which supports most of the services in the macrocell.
The solution to the above two problems often relies on the installation of repeater stations and split cells. In addition to economic reasons, in principle, these two methods cannot be used indefinitely because the communication quality has to be degraded when the system coverage is expanded; and the capacity is often sacrificed when the communication quality is improved.
As the number of users increases, macrocellular cells undergo cell splitting and become smaller and smaller. When the cells are small to a certain extent, the cost of building stations increases dramatically, and the shrinking cell radius also brings serious interference; on the other hand, blind areas still exist, and the high traffic volume in hot spots cannot be well absorbed; microcell technology is created to solve the above problems.
Microcell
Compared with macrocellular technology, microcellular technology has a small coverage area, low transmission power, easy and flexible installation, etc. The coverage radius of this cell is 30m~300m, the antenna of the base station is below the height of the roof, the propagation is mainly along the line of sight of the street, and the signal leakage on the roof is small.
Microcells can be used as a supplement and extension of the macrocell, and there are two main applications of microcells.
One is to improve coverage, applied to some blind spots and areas that are difficult to be covered by macrocells, such as subways and basements.
The second is to improve capacity, mainly applied in high-traffic areas, such as busy commercial streets, shopping centers, stadiums, etc.
Microcells generally form a multi-layer network with macrocells when used as an application to increase network capacity. Macrocells provide large area coverage as the bottom layer of the multi-layer network, while microcells provide small area continuous coverage superimposed on macrocells to form the upper layer of the multi-layer network.
Smart Cell
A smart cell refers to a cellular cell where the base station uses an adaptive antenna system with a high-resolution array signal processing capability to intelligently monitor the location of the mobile station and deliver the determined signal power to the mobile station in a certain way.
For the uplink, the adaptive antenna array reception technology can greatly reduce the multi-access interference and increase the system capacity; for the downlink, the effective area of the signal can be controlled within a radius of 10-20 wavelengths near the mobile station, so that the size of co-channel interference is reduced.
Smart cells can be either macrocell or microcell, and the network design using the concept of smart cells can significantly increase the system capacity and improve the system performance.
Cellular mobile communication development trend
The next era of mobile communication will belong to 5G, before that, national communication organizations are actively preparing for advancing the research and development of 5G technology. in mid-2013, South Korea’s Samsung successfully developed the core technology of 5G, which can achieve 2km long-distance transmission, as well as transmission rates of 1Gbps and above. in mid-2015, the International Telecommunication Union ITU officially named the 5G technology IMT-2020 and announced the schedule for 5G standardization.
In early 2016, China’s Ministry of Industry and Information Technology (MIIT) held a kick-off meeting for 5G technology R&D trials, marking a critical moment in the development of 5G technology in China. in early 2017, the 3GPP organization announced the official logo for 5G and established the specifications and permissions for the use of the logo.
Although 5G technology is not yet fully mature, the industry has basically reached a consensus on the future development of mobile communications. The white paper on 5G vision and requirements and network architecture design, which was released by the IMT-2020 Promotion Group, clearly defines the 8 key capability indicators and network architecture of 5G and also has a clear definition of 5G application requirements, including wider bandwidth access, denser connectivity requirements, and faster mobility requirements.
In addition, 5G will further reduce delay and power consumption, further improve reliability performance, and theoretically provide users with network speeds tens of times faster than 4G, and also enable large-scale interconnection with IoT terminals to exchange and communicate information between any items and meet the communication needs under high-speed mobile conditions.
Key 5G technologies include large-scale antenna arrays, ultra-dense network deployment, full-spectrum access methods, new network architectures, and multiple access technologies.
The advancement of 5G largely makes up for the shortcomings of 4G. Under the premise of maximum protection of existing facilities, how to use the existing 4G network to carry 5G is the top priority of the current planning for the 5G bearer network.
2019 is regarded as the first year of 5G commercialization by the global industry.
The arrival of 5G will enable mobile communication technology to break through the information connection between people and become a unified connection architecture and innovation platform for everything. 5G will generate deep integration with ultra-high-definition video, VR, AR, consumer-grade cloud computing, smart home, smart city, Internet of vehicles, Internet of things, and smart manufacturing, bringing new growth opportunities for all industries.
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