G stands for generation, which means quot generation quot. For example, 5G means the 5th generation.
1G refers to the first generation mobile communication system, while 2G, 3G, 4G and 5G refer to the second, third, fourth and fifth generation mobile communication systems respectively, which is really artificial.
The definition of 1G~5G, etc. Mainly from the perspective of rate, service type, transmission delay and various handover success rates.
first generation
The first generation mobile communication system is an analog cellular communication, and the characteristics of mobility and cellular networking are derived from the first generation mobile communication, but 1G is an analog communication with poor anti-interference performance. At the same time, the frequency reuse and system capacity are not high simply by using FDMA technology. There are two main standards, AMPS from America and TACS from Europe, which belong to the era of mobile phones.
Representative: Motorola 8000X, commonly known as quot mobile phone quot, supports basic functions such as voice and SMS;
Disadvantages: serial number and stolen number.
2G
The second generation mobile communication technology adds more multiple access technologies, including TDMA and CDMA, and 2G is digital communication, so the anti-interference ability is greatly enhanced. The second generation mobile communication technology has laid the foundation for the next 3G and 4G, such as the introduction of packet domain and the compatibility reform of air interface, which makes the mobile phone not only have single services such as voice and short message, but also connect to the Internet more efficiently. There are two main 2G standards, namely GSM organized by ETSI in Europe and CDMA IS95/CDMA2000 1x organized by TIA in America, with Qualcomm as the main force.
Representative: Nokia 7 1 10, supports WAP and Internet access;
Disadvantages: low transmission rate, unstable network and high maintenance cost;
third generation
In the first two generations of mobile communication systems, no international organization made a clear definition of what 1G and 2G are, but communication standardization organizations in various countries and regions have made their own agreements. But in 3G, ITU put forward IMT-2000, and only those that meet the requirements of IMT-2000 can be accepted as 3G technology. For specific requirements of IMT-2000, you can use Baidu Google Wiki or refer to related books. When ITU collected IMT-2000 standards from all over the world, communication standardization organizations in many countries and regions put forward their own technologies. For example, ETSI in Europe and ARIB/TTC in Japan put forward WCDMA technology with similar key parameters and technologies, and then set up 3GPP organization to standardize WCDMA. The so-called standardization is to form a unified agreement through technical PK and war of words to ensure the compatibility of their respective interfaces. TIA organization headed by Qualcomm also proposed CDMA-2000, and then gathered interest alliance to set up 3GPP2 organization, which also standardized CDMA2000. At that time, China CWTS also proposed TD-SCDMA, and later joined the 3GPP organization and merged with UTRA TDD from ETSI to complete the standardization. So the mainstream 3G standards are WCDMA, CDMA2000 EVDO and TD-SCDMA. Later, Wimax organized by IEEE was allowed to join the IMT-2000 family and become the 3G standard, that is, the third generation mobile communication technology.
Compared with 2G, 3G mainly adopts CDMA technology, which expands the spectrum, improves the spectrum utilization rate, improves the speed, and is more conducive to Internet services. At the same time, 3G evolution technology combines various access modes and adopts higher-order modulation technology and coding technology. New technologies such as multi-carrier bundling and MIMO are adopted to further improve the speed, and some functions are transferred from host computers such as RNC to base stations, which improves the response speed and reduces tim.
Advantages: CDMA system shows great development potential because of its simple frequency planning, large system capacity, high frequency reuse coefficient, strong anti-multipath ability, good communication quality, soft capacity and soft handover.
the 4th generation mobile communication technology
ITU also proposed the fourth generation mobile communication technology, namely IMT-Advanced family. Specific requirements can be Baidu Wiki Google. The 4G standard is mainly formulated by two organizations. One is the 3GPP organization, which represents the vast majority of traditional operators and communication equipment manufacturers. LTE/LTE-Advanced comes from our own hands. One is the IEEE organization, which mainly focuses on the challenge of IT to the communication industry. It introduced the successor of Wimax, namely WierlessMAN-Advanced. Qualcomm, which dominated the 3G era, and its 3GPP2 organization also abandoned their UMB technology and turned to LTE in the 4G era. LTE can be supported by Qualcomm and 3GPP2 organizations, which can be said to be a major blow to competitor Wimax. However, due to Qualcomm's participation, the benefit distribution of LTE is destined to be indispensable for Qualcomm. Let's judge whether it is good or bad.
At present, the most widely used 4G is LTE, so LTE is the change of 4G relative to 3G. The first is the great changes in the network architecture. LTE abandons the network structure of base station-base station controller/radio resource manager-core network that has been used in 2G and 3G. Instead, the base station is directly connected to the core network, which makes the whole network flatter, reduces the delay and improves the user experience. The core network abandons the circuit domain, the core network moves towards all IP, and IMS carries the original services. The key technology of air interface is also changed from 3G CDMA to OFDM, which is more feasible and adaptable than CDMA in large bandwidth. The large-scale use of MIMO technology improves the frequency reuse, and can obtain a larger spectrum bandwidth across carrier aggregation, thus increasing the rate. These technologies are important factors for LTE-Advanced to enter the 4G standard. Due to the demand for large spectrum bandwidth by 4G and the scarcity of spectrum resources in various countries and regions, more frequency bands will be used, compared with 3G.
80/850/900/1700/1900/2100 and other frequency bands. At present, LTE has become the mainstream of 4G with absolute advantage, and the Wimax family can be said to be completely suppressed. Therefore, 4G is also promising to end the chaotic situation standards of many contemporaries and achieve overall unification through LTE.
Representative: the popularity of Android, Apple iOS and Windows mobile devices;
Disadvantages: limited coverage and delayed data transmission;
5G
The fifth generation mobile communication technology has not been officially commercialized, but the concept of 5G is in full swing. The collection of 5G technical standards is expected to be confirmed by the end of 20 17. From 20 19 to 2020, it can be seen that global operators will carry out 5G commercial service trials one after another, including key applications such as Internet of Things, Internet of Vehicles, smart medical care, VR/AR and Industry 4.0. Drive a new industrial ecological chain.
The International Telecommunication Union IMT-2020 is also responsible for supervising the formulation of 5G technical standards. The advantages of new 5G technology have been expounded recently. According to the agency, the forthcoming general specification will support 654.38+0000 Internet devices per square kilometer, 65.438+0 milliseconds delay and the time for data packets to travel from one point to another, higher energy efficiency and spectrum efficiency, and downlink peak data download speed up to 20 GB/s ... Take self-driving cars as an example. Vehicles can exchange data at a speed of 0.00 1 sec.
Representative: wait and see;
Disadvantages: the development of science and technology is endless. Of course, 5G also has some shortcomings that need to be explored.
Simply compare the specific differences of the fifth generation mobile communication:
Typical frequency coverage radius of standard rate of network technology is 1G analog voice FDMAAMPS, tacs2.4k800/900/kloc-0-50-50km2 digital voice TDMA, CDMAGSM, cdma64k900/18005-10-/kloc.
WCDMA、CDMA2000、
TD-SCDMA
2M
1940- 1955
2 130-2 145
2-5km 4G digital audio and video images OFDM, IMT-AdvancedTD-LTE, FDD-LTE, WiMAX1g.
2300-2320
1755- 1765、 1850- 1860
1-3km 5G digital voice HD video IMT-2020 7.5G3300-3600, 4800-5000 100-300m.
With the development of mobile communication technology, the use of low frequency is close to saturation.
Of course, cell radius is not only determined by carrier frequency, but also related to many other factors, such as natural environment, user density, human interference and so on.
Evolution of technical standards of mobile communication
5G standardization will be completed in two stages.
The first phase is a mid-term milestone of 5G standardization, which is expected to be completed by the end of 20 17. 3GPP plans to freeze relevant standards before 20 17 and 12.
In the second stage, 3GPP hopes to achieve the second milestone around the middle of 20 18, that is, to complete the standardization of stand-alone mode.
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