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When it comes to trunking communication, you may feel strange, but in life, we can often see police uncles holding walkie-talkies for mutual communication. These walkie-talkies are basically handheld terminals of trunking system. Trunk communication, like public mobile communication, has experienced the transition from analog system to digital system, but the development of trunking communication is much slower than that of public mobile communication, and people’s understanding of trunking communication needs to be improved, so it is necessary to introduce trunking communication.oneOverview of trunking communication
Generally speaking, trunking communication is a kind of mobile communication system which is realized by base station relay. It is a communication system between public mobile communication and ordinary walkie-talkie. At present, it is mainly used for command and dispatch and emergency command of various special departments in China.
"Cluster" is derived fromTrunkingorTrunkedThese two English words are translated,TrunkThe original meaning of is "tree fork", but it can be translated as trunk or trunk line related to communication. But the relay andRelayRelated. Therefore, later, the older generation of mobile communication experts thought that translating it into relay or trunk line would be confused with real relay and trunk line, but it was determined to be a cluster in the sense that it set small groups into large groups, so cluster communication was so catchy.
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Schematic diagram of trunking communication system
fromTrunkedAll available channels of the system can be shared by all users of the system, that is, any user in the system who wants to talk to another user in the system can communicate with each other by using idle channels under the control of the central console.
In addition to the functions of ordinary telephone, trunking communication system also has the following characteristics:
(oneThe hierarchical management function of users: the cluster system divides users into several groups, and each group has different priority levels. In each group, different priorities can be set for users. During the call, members of the group with high priority can directly seize the right to speak of members of the group with low priority.
(2) Call function: Cluster system provides group call, emergency call and broadcast call, etc.threeKind of "one call and one hundred answers" function. The so-called group call refers to the one-to-many intercom call initiated by the user, and members in the group can press.PTTKey to apply for the right to speak, during the call, only one member can speak at the same time, and other members can only listen; Emergency call is a special intercom mode in an emergency, which has the highest call priority and is used to inform the pre-designated users or groups in the shortest time and in the most convenient way. Broadcast call is a special group call, which is different from group call in that only the caller can speak, but the called party has no right to speak.
This function seems to be the same as the ordinary walkie-talkie, but the biggest difference between them is that although the ordinary walkie-talkie can also achieve the function of "answering every call", there is no priority between each user of the ordinary walkie-talkie and it cannot be grouped. Once the "other" users are tuned to the same frequency, they can hear the call and initiate the call, thus causing interference or leakage.
(three) Shake and revive function: When a cluster terminal is accidentally lost or other special circumstances occur, in order to avoid the leakage of important information, managers can use the remote killing function to kill in the air at this time, so that it can not be turned on; For recoverable remote shooting, the system can also use the resurrection function to make the terminal work normally.
(four) Shared frequency: A small number of dedicated frequencies originally allocated to various departments are managed centrally for all families to use together, thus improving the effective utilization rate of frequency resources. Just like cars and roads, when there is only one lane, cars can only travel in sequence in this lane, and cars may travel slowly. When there are more than two lanes, cars can "see the needle", which is "sharing", which can greatly
(five) Shared facilities and shared coverage area: Because of the frequency sharing, it is possible to build facilities such as control centers and base stations separately built by each family to form a larger coverage area, and each family can set up a virtual console to control and contact their own users, thus greatly saving network investment.
(six) improve service: if the network is jointly built, the channel sharing can adjust the surplus and deficiency, and the total number of users supported by the total channel when the network is jointly built is much larger than the total number of users supported by the total channels dispersed to each network when the network is decentralized, thus improving the service quality; Centralized network construction can also strengthen management and maintenance, thus improving service level and enhancing system functions.
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Application of trunking communication system
2The development of cluster system in China
Our country is1989In 2000, the simulation cluster system was introduced,1990Put into use in, mainly based onMPT1327Signaling standard is developed, and has been applied and popularized to some extent. although2001The Radio Administration of the Ministry of Information Industry issued "About"800MHzNotice on matters related to the use and management of trunking frequency (No.[2001]518No.), which stipulates that all analog trunking communication systems are in2005yeartwelvemoon31sunIt had to stop running before, but some traditional analog private networks are still running today.
With the development of digital communication technology, trunking communication system has also begun to develop to the second generation of digital technology, the most important feature is the adoption of.TDMA(Time division multiple access)andCDMA(code division multiple access)Communication mode. ITU (ITU) also recommended some digital trunking communication systems, such asiDEN(Integrated Dispatching Enhanced Network),TETRA(Europe-wide trunking radio)andFHMA (frequency hopping multiple access), etc., and four technical systems are recommended in China’s standards, namelyTETRA 、iDEN、GT800andGoTa.
(one) TETRAsystem
TETRA[2](Terrestrial Trunked Radio) is the European Telecommunications Standards Institute (ETSI,European Telecommunications Standards Institute) digital trunking standards, a lot of reference.GSM(Global System for Mobile Communications) concept, adoptTDMA(Time Division Multiple Access) system, carrier bandwidth25kHz, pointsfourTime slots, the modulation mode is π/4DQPSK, support cellular continuous coverage. The main working frequency band is350MHz 、400MHzand800MHz.TetraThe standard gives more consideration to command and dispatch, defines different network working modes, and specifies voice, circuit data, short data messages, packet data and other services as well as a variety of additional services.TETRAThe dispatching function of the system is relatively perfect, so it is very suitable for private networks, especially for military, armed police, public security and law enforcement units. It is one of the most widely used technical standards in China, such as Zhengtong Network in Beijing and Special Network for Asian Games in Guangzhou.
(2) iDENsystem
iDEN(integrated Digital Enhancde Network) yesMotorolaA digital trunking mobile communication system developed and produced by the company has the functions of duplex telephone interconnection, data and short messages, and integrates digital dispatching communication and digital cellular communication into one system, which mainly works in the following aspects.800MHzFrequency band.
iDENBased onTDMAScheduling communication in multiple access mode/Cellular telephone integrated system. On the basis of traditional large-area dispatching communication, it absorbs the advantages of digital cellular communication, enhances the interconnection function of telephone, and adopts cell multiplexing cellular structure to improve the coverage capacity of the network.iDENCarrier bandwidth of the system25kHz, pointssixTime slots, modulation mode isM-16QAM, support scheduling, telephone interconnection and circuit data./Fax and other services.
(three)GoTaDigital trunking communication system
2004yearthreemoon18sun, ZTE launched its world-leadingGoTa(Global open Trunking architecture) digital trunking communication system. This is the first time in the world that a digital trunking communication product with independent intellectual property rights has been released by a China enterprise.GoTaDigital trunking communication system is also the first one in the world based on.CDMA(Code Division Multiple Access) technology of real digital trunking system.GoTaThe meaning of is open cluster architecture, which adopts the currentCDMAThe latest wireless technology and protocol standards in mobile communication system are optimized and improved, so that it can meet the technical requirements of the cluster system, and at the same time, it has strong common network operation ability and business development ability, which can fully meet the future development needs of the cluster. Compared with several mature cluster technologies at present,GoTaThe trunking system has completely independent intellectual property rights, and the air interface and architecture adopt the technology adopted by the current third-generation mobile communication system, with higher spectrum utilization rate, larger capacity, more support services, less investment and convenient deployment, thus having broad technical and business development space.
existGoTaIn the design of the system, the characteristics of digital trunking communication network are fully considered, and the system is developed and designed for mobile operators, and the needs of mobile business users are fully considered. A terminal can integrate a variety of communication services such as trunking dispatching service, ordinary voice service, packet data service and many value-added services (SMS, location) into one network.GoTaThe system has the characteristics of high flexibility, excellent cost performance and comprehensive functions, which opens up more profit space for operators.
At present,GoTaHas been successfully applied to2005The 10th National Games in Nanjing in 2008,2008The first year of29Qingdao Olympic Sailing Competition and2009The 11th National Games of Shandong in 2008.
(four) GT800
GT800The system is developed by Huawei based on.GSMDigital trunking system based on technology. Huawei company research and developmentGT800The system is geared to the needs of domestic digital trunking market, referring to the business characteristics of existing digital trunking systems, especially in the aspects of fast calling, group service, priority control, security and confidentiality, and fault weakening, and can provide complete trunking dispatching services that meet the needs of domestic professional mobile communication. At the same time, in order to meet the needs of users for high-speed data services,GT800passGPRSTechnology, realize variable rate data transmission function.GT800It can provide a wide range of services, including basic calls, short messages, cluster scheduling, priority preemption, fast connection and location-based routing, etc., and also provide services based onGPRSData service.GT800It is suitable for the common network operation of cluster communication, and also suitable for the self-built private network of civil aviation, railway, water conservancy, municipal administration, transportation, construction, emergency rescue and disaster relief, mining area and other professional departments.
three, technical indicators of four trunking communication systems.
At present, trunking communication system has been widely used in all walks of life, such as railways, civil aviation, hydropower, oil fields, ports, light rail and subway, public security, inspection, law, security, military, armed police and other departments, and four technical systems are in use. In order to facilitate comparison, we list the technical indicators of the four trunking communication systems.[4]As follows:
References:
[1] Zheng zuhui.Trunk communication system and its digitization.Jinri electronic.1996.8
[2]Terrestrial Trunked Radio. http://en.wikipedia.org/wiki/Terrestrial_Trunked_
Radio
[3] Zhang changsheng.Course of trunking communication system
[4] General situation of global digital trunking market development. http://tech.c114.net/159/a151855.html