colonycommunication system It is used for group schedulingCommand and communicationOfMobile communication system, mainly used in professional mobile communication field.The available channels of the system can be shared by all users of the systemAuto SelectChannel function, which isshared resource, cost sharing, shared channel equipment and services of multi-purpose, efficient wireless dispatching communication system.
Trunking communicationThe biggest feature ofPTT(Push To Talk), connect in a push to talk mode, and the called does not needOff hookIt can answer, and the connection speed is fast, and it can supportgroup call And other functions, its operation mode isSimplex、Half duplexMainlyChannel dynamic allocationAnd users have different priorities andSpecial functionsWhen communicating, you can respond with one call.
Back to its birth, the concept of cluster really starts fromWired telephoneThe concept of "relay" in communication comes from.In 1908, E.C. Mo1ina published the concept level of "relay" curve, which proved that a group of usersTrunk lineThe probability ofTrunk lineOfUtilization。The concept of "cluster" is applied to radiocommunication system , consider the channel as a relay.The concept of "cluster" can also be understood from another perspective, that is, by analogy with electromechanical (crossbar) switches, the wired trunk is regarded asWireless channel, switch theMarkerRegard asCluster systemWhen the relay is fully utilized, it can be considered as the channel of the cluster.colonysystem controllerIt can dynamically and automatically allocate the limited channels to all users of the system, which is actually the full utilization of channels or the term "channel sharing" that we often use.
development history
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China began to introduce in 1989Simulation cluster system, put into use in 1990.along withdigital communications technologyThe development of trunking communication system has also begun todigital technique The main feature of development is the adoption ofTDMA(Time Division Multiple Access）AndCDMA(Code Division Multiple Access）Communication mode.However, China's trunking communication applications mainly stay insimulation techniqueThe application of digital trunking is less.At the same time, in order to meet their different use requirements, enterprises using clusters have adopted the scheme of building cluster communication networks independentlyInter network interconnectionInteroperability、Frequency resourcesThere are many problems in use and overall construction.In addition, foreign communication giants controlcore technology And set patents, etcIntellectual property protectionBarriers, making the internal interface basically closedOpennessVery poor, system andterminal equipmentmarket priceThe high level also restricts the industrialization process and scale application of China's digital clusters.For China's digital trunkingIndustrial development"Embarrassing" situation,Ministry of Information IndustryLed the development of ChinaCluster technologyDevelopment planning, and《Regulations on Telecommunications Administration》The first time digital trunking was incorporated into the basicTelecommunication serviceCategory, at the same time organizing six major domesticTelecom operatorsCarry out commercial experiment of 800 megabyte digital trunking in China.From the experiment of operators, there areChina SatcomZTE's CDMA based technology systemGoTaCommon network commercial experiment,China RailcomZTE's GoTa andHuaweibe based onGSMTechnical institutionalGT800Commercial experiment of digital trunking sharing network of two technical systems.The commercial experiments in recent years are not idealOperation modeMaturity andApplicability, and the publicMobile communication serviceWe have not yet explored a commercial operation mode that can satisfy the country.
Obstacles
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Analyzed from the practice of digital trunking commercial experiment, the main reasons for the slow development of digital trunking network sharing in China are as follows.DevelopingDigital trunking technologyIn consideration of nationalCommunication securityAnd hundreds of billions of yuan to buy overseasCommunication equipmentOfInvestment costThe state emphasizes that we need a digital trunking communication system with independent intellectual property rightsEthnic enterprisesTo develop national digital trunking technology standards, control core technologies, and break foreign digital trunking technology monopoly.Although ZTE's GoTa based on CDMA technology system has achieved rapid development in China, it has successfully servedTianjin PortWeifang city emergency linkageASEM Finance Ministers' Meeting、Nanjing 10th National Games、Qingdao Olympic Sailing CompetitionAnd other major domestic events and sports events, which have won more than 100Invention patent, and has already gone abroad, but it should also be noted thatEurope and AmericatraditionDigital trunking technologysystemTETRA、iDENIn comparison, China's digital trunking technology system still has some gaps in terms of network size, call delay, technology evolution, terminal quality and industrial chain.
Local supervision
Although in 2001Ministry of Information IndustryRadio managementGXFXB No. 518 [2001]Notice on the Use and Management of 800MHz Trunking Frequency, which stipulates that all analog trunking communication systems must stop operation before December 31, 2005. However, some traditional analog private networks are still operating in experimental cities that have met the conditions for sharing networks, and the local radio management department has not actually performed its duties according to the requirements of Circular 518 due to its own interests.
Traditional users
Some depend on the stateFinancial appropriationThe powerful departments and industries with strong economic strength relying on resource monopoly have the illusion of building their own networks when the national digital trunking operation policy is not yet clear. They only consider the interests of departments and industries, not big accounts, and blindly build their own private networks, resulting inReinvestmentAnd the waste of resources, which is also one of the factors that China's digital trunking network construction is difficult to promote.
market demand
Chinese enterpriseseconomic form It is still in the initial stage of cost priority.Over the past 20 years of reform and opening up, Chinanational economyHas achieved rapid development,gross domestic productDouble digit growth for three consecutive years, manyEthnic enterprisesRapid development, but the same asEurope and Americadeveloped countryIn contrast, the economic form of Chinese enterprises is still in its infancy, and the overall economic level is not high.While many European and American enterprises have transitioned from cost priority to efficiency priority, most Chinese enterprises are still in the cost priority stage. When facing cost and efficiency, cost factors are considered more.In the United States, digital trunking is widely used in industries with high job mobility, such as construction and logistics, but it is difficult to promote it in China.
Operator concerns
Traditional analog private network users generally choose to build their own networks. For example, public security departments need to build public security private networks in consideration of communication security and confidentiality.For some users who do not have the economic strength to build a network, it is difficult to say that users can access the network even if they doARPU valueAlso low, resourcesContribution rateVery limited.along withCellular technologyThe development of public network operators throughGrouping dataThe technology has been able to5G networkPOC (PTTowerCell, POC for short) service is provided on theOn timeIt is too long, occupies too much resources and affects the communication of public users, but it can meet the requirements of small-scale low-end users with low connection time, which is not small for the common network cluster operatorsimpact force。Faced with less than idealmarket environmentOperating enterprises are full of worries.
Lack of talents
Cluster technologyIt has been developed in China for more than 10 years, but it exists in the form of private network, mainly for internal use of the unit, and lacks the operation experience of providing services through a common network.The development of digital trunking network requires ascale effect , leading domestic telecom operators have little interest in digital trunking, rather thanLeading operatorThere is also a large lack of operation talents, more specifically, the lack of digital cluster operation talents. Therefore, to some extent, the lack of operation talents is also a factor limiting the development of digital cluster shared network.
Operation mode
China's economyDevelopment andUrbanization processThe acceleration ofSocio economic formMore and more people are seeking efficiency, and the society is eager to deal with emergencies efficientlyEmergencies. The requirements for information security are constantly increasing, and the frequency resources are becoming increasingly tense. How to improve the frequency utilization rate, achieve the optimal allocation of resources, and strengthen the government's rapid response to emergencies and emergenciesRisk resistanceHas become the primary task we face.In this case, digital trunking network sharing will becomeFuture figuresThe development direction of trunking communication, and the operation of China's digital trunking network must reflectsocial resultsOn the basis ofeconomic performanceAfter allSars, earthquaketerrorismIn case of emergencies, human life is the first. In this case, it is impossible to use economy to measure the role and value of cluster networking.
Operational Case
In terms of shared network operation of digital trunking, there have been relatively successful cases in developed countries such as Europe and the United States. Nextel in the United States is a relatively successful operator in developing shared network digital trunking, but it was born when the United States simulatedMobile communication standardChaotic times,NextelWith GSM likeiDENThe network has made great achievements, but China does not have such a good market environment and opportunities;EuropeFinlandGovernment choiceFinland TelecomSONERACooperate as an operator to set up a special operating company for operationVIRVEThe company is funded by the Ministry of Internal Affairs by 60%, SONERA by 40%, and the operating company is only responsible forPhysical networkAnd user management and communication management are carried out by user departments in their own virtual private networks;BelgiumThe government set up a specialASTRIDAs a national digital cluster governmentShared networkIn ASTRID,federal governmentIt holds 61% of the shares, and the local government holds 39% of the shares. The federal government allocates funds to ASTRID company every year for operationmaintenance cost 。
Current operation mode
At present, many experts in the industry generally agree that the digital trunking operation mode is "shared network dedicated (serving the countryPublic safety）, private network sharing (serving enterprisesproduction scheduling ）”This paper believes that the operation mode of shared network and private network parallel is not conducive to national absorption in the aspect of shared network dedicated service for public security communicationExternal fundsTherefore, it may carry a heavy investment burden and causeCommunication resourcesThe situation that cannot be effectively utilized;In terms of private network sharing for enterprise production command and dispatching, it is likely to return to the era of analog cluster development, and work independently to build a network. Because China's current economic situation is not enough to support the operation of a digital cluster network, industries with strong economic strength, such as airports and ports, may choose to build their own networks.
Fit mode
China may refer to Finland andBelgiumIn combination with China's national conditions, we will establish a "national team" controlled by the government to manage it. If necessary, we will sacrifice the communication needs of public users to ensure the communication safety of important departments such as fire protection, police and rescue, and form our own digital trunking common network operation mode.The development of digital trunking in China in the future will serve public security command and production scheduling. Public security is the top priority, followed by production scheduling. That is to say, the digital trunking network sharing operation must mainly reflect social benefits. For example, the governments of Finland and Belgium in Europe, in the public security oriented network sharing operation mode, the government must take the lead,Establish a national public with the government as the main bodySafe operationranks.
To promoteWireless mobile communicationWith the healthy development of the industry, the government may wish to guide the public network operators in the future 3G publicmobile communicationOpen online based onSIPAgreedPOC(PTTowerCell (POC for short) service, as a value-added service of public mobile communication, competes with the cluster shared network in the low-end non professional cluster user market, handles the competitive relationship between the shared network cluster and the public mobile communication network, and promotes the healthy and healthy development of the wireless mobile communication industry.Form a digital trunking network to serve national public security and high-end enterprise production scheduling, supplemented by public network POC service for low-end non professional users;Professional clusters mainly reflect social benefits, supplemented by economic benefits, and public network POC mainly reflect economic benefits, supplemented by social benefits. The two complement each otherCoordinated development。
development strategy
Because trunking communication and public mobile communication faceTarget customersDifferent from the development of traditional public mobile communication, the development of digital trunking is different from that of traditional public mobile communicationDevelopment modeAfter all, the market is the most objective standard for testing a product.Considering China's regional and industrial economic developmentout-off-balance, to reduceRisk avoidanceBlind investmentThe development strategy of digital trunking shared network must break the traditional development model of public mobile communication and follow the principle of "market first, network later"market development The strategy is to adopt the development idea of stages, industries and regions.
1. Phased development means that the current development of digital trunking network should take serving national public security as its own responsibility. At the initial stage of business development, it should be built in cities above the sub provincial level to serve public security, fire protection, traffic police, first aid and urban management as the main bodyUrban emergency linkage system。When the conditions are ripe, gradually build the main projects covering the whole countryprovincial capitalCityPrefecture level cityAnd three-level urban emergency linkage system of county level cities.
2. The sub industry is aimed at the strong economic strength and clear productionDispatching commandIndustrial customers who need to customize theVirtual private networkThe solution attracts users in civil aviation, railway, port, water conservancy, transportation and other industries to access the network.
3. Subregional supportChangjiang delta、Pearl River Delta、Bohai Rim The economic strength of the Yangtze River Delta, the Pearl River Delta, and the Bohai Rim economic circle will play a leading and radiating role, and gradually promote from the east to the west, from the coast to the inland, and finally build a digital trunking network covering the whole country.
From serving Weifang emergency linkageQingdao Olympic Sailing Competition、Shandong PrisonAccording to the development of urban law enforcement in Jinan, Shandong digital trunking network has basically followed the development mode of "market first, network later" by stages, industries and regions, which has been specifically reflected in serving urban public security and enterprise production scheduling, and has achieved step-by-step results.
relationship
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Relationship with PoC
3G network
Digital trunkingAnd 3G networksPoCBusiness can be realizedPTTFunction.Digital trunking is a solution based on signaling channel. During the call, voice data and signalingDataGather them to the pre established channel for transmission;PoC service adoption of 3G networkVoIPTechnology,Core networkbe based onIMSArchitecture, inmobile terminal And businessapplication server High level signaling protocol is used to bind voice data to the IP link.Digital trunking and PoC in the technical realization, network requirements andmarket positioningThere are great differences in all aspects.Digital trunking is mainly used in mobile private networks, while PoC services are mainly for the publicCellular mobile communication systemOfWireless value-added service。
IDEN is created byMotorolacompanyIt also adopts TDMA system, and is divided into 6 channels at 25kHzTime slot(The 25kHz bandwidth has been developed to be divided into 12 time slots).itsVSELPSpeech coding and 16QAMmodulation technique They are quite advanced.IDEN systemIts original design is for common network, so it integrates command and dispatchingDuplexInterconnectionGrouping dataandSMSIn one way.
IDEN system is mainly based on dispatching and is designed according to the public network, so its basicdispatching systemFeatures include:Group callCall, private call, call prompt, call display.Advanced functions of dispatching include:priority, emergency callstatus information , multi group scanningRegional restrictions, isolated station operationDispatching deskEtc.IDEN system also hasVirtual networkFunction, viaVirtual private network（VPN），end userIt can manage the terminal configuration of its end users, including opening accounts, adding new services, changing the dispatching private number, group numberphone number, regrouping and obtaining detailed call lists and usage statistics at any time.
（3）GoTa
GoTa (Global Open Cluster Architecture) is a kind ofZTEIndependent research and development based onCDMA1XTechnology: Digital for New Technology EvolutionTrunking communication systemThe goal is to meet the needs of common network clusters and take into account the application of private network clusters.
GoTa has certainTechnical advantages, which solves the problem of realizing cluster service based on CDMA technologykey technology 。The sharing mode is also used to deal with the communication connection, so as to reduce the number of calls handled by the networktime delay。GoTa has fast access, high channel efficiency and spectrumUsage, higher usersprivacy, easy to expand and support multiple business types and other technical advantages.
In the design of GoTa system, the characteristics of digital trunking communication network sharing are fully consideredMobile operatorDevelopment design, fully consideringmobile commerce Users can use one terminal to group cluster dispatching service, ordinary voice servicedata service , numerousvalue-added service (SMS, location) and other communication services are integrated into one network.The features of GoTa system, such as high flexibility, excellent cost performance and comprehensive functions, open up more profit space for operators.
（4）GT800
The GT800 system is composed ofHuaweiThe company's R&D is based onGSM technologyOfDigital trunking system。The GT800 is based on GPRS and GSMRtechnological developmentAnd its second phase will beTD-SCDMATechnology integration.HuaweiThe GT800 system is developed for domestic digital trunkingmarket demand, referring to the business characteristics of the existing digital trunking system, especially in fast call, group business, priority control, securityFault weakeningA lot of work has been done in the aspect of providing a complete cluster scheduling service to meet the needs of domestic professional mobile communication.At the same time, to meet the needs of users for high-speed data services, the GT800GPRS technology, achieving variable ratedata transmissionFunction.In the second phase of the GT800, TD-SCDMA is introduced to further provide data services with a maximum rate of 2Mb/s.
The GT800 can provide a wide range of services, including basic calls, short messages, cluster scheduling, priority preemption, fast connection and location-based routing. It also provides GPRS based data services.The GT800 is suitable for the common network operation of trunking communication, as well as civil aviation, railway, water conservancy, municipal administration, transportation, constructionRescue and disaster relief, mining area and other professional departments build their own private networks.
2.3G PoC service PoC service standard of 3G network mainly consists ofOMAAnd based on3GPPand3GPP2IMS network architecture.
PoC is a two-way, real-time, multi-partycommunication mode , allowing users to communicate with one or more users.This service is similar to the mobile intercom service - the user presses a key to talk with a user or broadcasts to a group participant, and the receiver can take no action after hearing the voice, such as not answering the call, or after hearing the voiceSenderBefore the sound is heard, the call must be received and notified.After the initial voice is completed, other participants can respond to the voice message.PoC communication isHalf duplexAt most one person can speak at a time, and others can answer.
PoC's business features include:
● PoC groups can be predefined or temporarily established（Adhoc）Or similarchat roomBy the userChat group。
● Users can speak by asking for the right to speak. The right to speak is controlled by a set of strict control mechanisms.
● PoC has the right to speakBusiness EntityGrant, if for a period of time（Business ProviderIf the user does not speak after setting), the speaking right will expire after timeout.
● PoC business entities canCalled userBefore accepting the session invitation, send instructions to the initiating user. If no user receivesMedia StreamingPoC participants can get hints.
● PoC can interact with existing voice like services on the Internet, such as online games, including audio functionsInstant MessagingEtc.
In PoCArchitectureThe control of the user's voice is a very important concept in.The control of voice is mainly inUser PlaneTo complete, based onRTP/RTCPAt the same time, OMA also defined an APP application of RTCP, called TBCP protocol, to realize the distribution of PoC media streams and the control of voice.The signaling control of the session is mainly appliedSIP/SDP, which realizes the management of SIP registration, routing and security, thus ensuring the completion of PoC sessions.
(2) IMS support for PoC
I MS's support for PoC mainly realizes the registration, security and SIP of PoC servicesSignaling route, SIP signaling compressionAddress resolution, hidden identity management, billing and other functions.
In IMS registration, the user establishes thePDPcontext, request via GPRS orDNS resolutionProcess discovery in IMSP-CSCF。P-CSCF forwards the registration request toI-CSCF, inquire through I-CSCFHSSAnd foundS-CSCF。Implemented in S-CSCFRegistration process。In this process, PoC users and S-CSCF realize authentication and authentication of both parties through AKA algorithm.
After the user is successfully registered and authenticated, the PoC user can initiate a group call request.Add "+g.poc.talkburst" or "+g.poc.groupand" to the tag of the SIP header contact of the session invitation to indicate that this is a PoC group session.P-CSCF forwards the call invitation to I-CSCF and asks the address of the S-CSCF to which it belongs, thus forwarding the invitation to S-CSCF.S-CSCF transfers the session invitation to the responding PoC according to the business trigger point through iFC (initial filtering rule) downloaded from HSSserver。The PoCserver controls the session and forwards the session invitation to other users in the group through IMS. After media authorization and negotiation, the group call can be established.
PoC service billing is based on IMS billing framework, which can be based on event billing, group session billing, speech billing, etc.
In addition, the PoC service also applies SIP in IMSsignallingCompression function. Signaling compression is to save link resources and reduce latency. It implements SIP signaling compression anddecompression 。At the same time, IMS also supports the implementation ofUser IDHidden.In addition, PoC session media bearer is considered in IMSresponse timeBalanced with media QoS, it uses the QoS level of SIP signaling.
business relations
1. Technical differences
Digital trunking requires forward and backwardresource sharing, that is, in a cellCoverageAll cluster users in the same group share the same wireless andWired channel。The number of users carried by a channel is unlimited for the number of clustered mobile phones, which can greatly increase resourcescarrying capacity。In the case of a single channel resource, theoretically, it can support infinite cluster mobile phones for scheduling.
In PoC, each user needs to occupy independent wireless and wired resources, which means that the resource occupation depends on how many users enter the group call when the service is implemented. For PTT, the resource occupation will be multiplied.If there is only one wireless channel, PoC service cannot be provided. At least two wireless channels must be provided to ensure one-to-one PoC calls.
2. Differences in key indicators
The most fundamental difference between digital trunking and PoC is the difference of its key indicator - connection delay.
The connection time of PoC is generally more than 2-3 seconds, sometimes even more than 10 secondsFrequency of useIf the network signal is increased or poor, the connection time will be longer.The connection time of digital trunking is controlled within 1 second or less, which is the fundamental reason why digital trunking has not been replaced by mobile public network, and also its core competitiveness.
The delay index of several foreign digital trunking networks is within 1 second. The general group establishment delay is 400ms-700ms, PTT<300ms, and the general group call establishment and maintenanceTime distributionIt ends in 5-12s, and PoC basically cannot meet this requirement.
3. Different market positioning
The market positioning of digital trunking is divided into two types: professional user market and public user market.Professional digital trunking users are generally estimated to beMobile userAbout 10%, according to the estimation of China's 300 million mobile users, there are also 30 million users of digital trunkingMarket space。
PoC services are mainly for individual users. The dominant voice and integrated services are the main sources of its revenue. At present, voice and integrated services are also the services facing the greatest competitive pressure for global mobile operators.
First of all, because the service objects of digital trunking include government, units, etcGroup customersMainly, not very sensitive to price;Secondly, any revenue generated by professional cluster scheduling service is generated under almost no competition. At the same time, the scheduling service is mainly implemented in the network and does not existInter network settlementCost;In addition, due to professional needs, the product's substitutability is very lowloyaltyVery high, low off network rate, which can save some money for digital trunking operatorsoperating costs 。
Compared with other services of operators, the PoC service based on mobile public network is basically the same and has replaceable characteristics, so the PoC serviceoperating activitiesBoth products and products are facing strong competition in the market, the prices of products and businesses are declining, the profit margin is not high, and the settlement cost also accounts for a large proportion, which directly leads to the bottom line that must be considered when pricing products and businesses.
5. Different coverage points
Digital trunking customers mainly focus on work and need toWork areaEffective coverage, such as outdoor coverage in urban areas and key points in working areasRegional coverageAt the same time, there is basically no need to cover cluster users in rural areas and other remote areas. This simple coverage requirement of digital trunking can fully utilize mature wirelessMeans of communicationIt should be satisfied. For example, all BTSs supportRegional systemIn this way, the system investment is saved to a large extent, and the coverage means for local key areas are also very mature, such as government buildings, factory headquarters, etc., which can meet the coverage requirements at a low cost.
For the scheduling demand brought by emergencies, the demand can be met through the operation of isolated stations and the off network direct connection, but the proportion of this situation is extremely low.
For PoC service, due to the user'smobilityIt is very large and widely distributed. It can be said that all places where people exist need to be covered, so a large amount of network investment is required. Even if only basic coverage is considered, it is roughly estimated that it is at least 2-4 times the coverage investment of digital trunking network.
6. Different capacity requirements
according toMarket shareAccording to the analysis of, even if the proportion is 10%, it is enough to show that digital trunking does not require high capacity, so digital trunking is under constructionCluster networkAt the initial stage of the network, there is no need to consider the pressure of capacity. It can be understood that in terms of capacity, the digital trunking system only needs 10% of the capacity resources of the mobile public network to operate normally and meet the capacity requirements of digital trunking users. This is undoubtedly a major advantage for building a digital trunking network.
For PoC service, in order to ensure capacity demand, mobile operators have to useCommunity systemPlan to build a network, and reduce the transmission power of the base stationPitch angle, lowerBase station antennaHeight and other methods to increase the density of base stations and improve the areaUser capacity。
The development of digital trunking communication in China is still in the initial stage compared with the developed regions abroad. The digital trunking system with independent intellectual property rights has just begun to develop. From the perspective of the market development of digital trunking communication and the development of national industries, there is a large space for development,This situation is both a challenge and an opportunity for the future development of digital trunking communication system in China.
In the process of the development of digital trunking communication in China, we should first deal with the publicMobile communication systemRelationship.Digital trunking communication is a special mobile communication system that provides group users with command and dispatching services, while public mobile communication is a public mobile communication system that provides voice and data services for ordinary users.Their positioning is different, and their technical characteristics are also different.Avoid repeating the detour of providing public network services through the cluster system in the past.At the same time, from the public mobile communication system technologyDevelopment levelIt can't replace the cluster system. The public network can only provide PTT service as a value-added serviceperformance index It is far from meeting the needs of group users for professional command and dispatching communication, and also can not provide various types of cluster communicationService qualityLevel and priority.These functions are very important in the cluster network, especially in the cluster shared network.
Two development modes
Secondly, the development of digital trunking should be divided into two development modes: common network and private network.The shared network cluster provides services with different needs and priorities to different cluster user groups in the same network through VPN.Compared with the private network, this application mode hasnetwork resourceAnd high utilization rate of frequency resourcesNetwork operatorOperation and maintenance network can provide users with more professional services, reduce network operation costs, and facilitate communication between various groups and departments to achieve coordination.Cluster sharing network is the future development direction of cluster communication.However, it should also be recognized that some private networks cannot be replaced by the common network cluster. For some departments with high call quality and priority requirements, the common network cluster may be difficult to meet the requirements, or it may require high network costs.Therefore, the development of private networks cannot be ignored when promoting the development of cluster shared networks.
Quality assurance
Third, in terms of cluster network operation, the issuance of cluster network sharing licenses should be strictly controlled, and operators with certain strength should be encouraged to develop cluster network sharing, ensure network quality, and avoid repeated investment and construction.Operators should be guided to correctly position the cluster network and focus on professional cluster users to avoid overlapping users with the public mobile communication system.New market space should be developed.At the same time, operators should also be encouraged to develop value-added services for cluster users on the basis of cluster services to achieve social and economic benefits.
Development trend of PoC
PoC service utilizes public mobileCellular networkThe feature of wide coverage enables mobile users to realize point to multipoint group calls, so as to share information effectively and timely among multiple people.PoC services can also bring IP based multimedia applications to users, such as interactive games.PoC service enables group call users to be "always online". This "always online" feature enables members participating in the call to call as long as they press the PTT key.
Although PoC has many advantages, we should also see the shortcomings of PoC. The most important thing isCall establishmentThe delay performance and call time delay performance are not high, mainly because PoC is based on public mobileCellular networkVoIP technology.Therefore, PoC cannot be applied to emergency linkage and emergency call like digital trunking communication.At the same time, due to the reliability andSecurityNot high, so PoC cannot be applied to departments with high security requirements.PoC business is more used in companies, hotels and leisure entertainment places to enrich people's communicationcontact informationAnd increase people's communication pleasure.
The future development of PoC services should pay more attention to improving service delay performance, enriching service types and providing more service functions.Try to shorten the PTT call delay, develop PushtoX (X can be text, voice, picture, video and other forms) services, and add functions such as user priority and disaster processing to improve PoC services.
PoC can use public honeycombMobile networkResources realize the point to multipoint function, so thatBroadband serviceMore enriched, and mobile operators can use existing network resources to quickly deploy and provide PTT services.However, through analysis and comparison, it can be seen that PoC services cannot meet the requirements of digital trunking in terms of resource utilization, user capacity, security and reliability.OMA is actively developing the latest PoCtechnical specificationsThe PoC service is expected to provide functions such as emergency scheduling and user priority, and improve the connection delay performance. Moreover, 3GPP has also formulated PoC related specifications in the R6 specification.It can be seen that PoC will be a very important service in the future 3G, but PoC cannot replace digital trunking after all, and digital trunking will still be the most important and effective technical way to realize cluster functions such as command and dispatching
Developing the future
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First driving force
China Satcom、China RailcomBoth of them regard digital trunking business as the development focus to promote, but both of them focus slightly.With the help of China Satcom“satellite communicationAnd the integration of the earth and the sky, using the combination of satellite communication and ground trunking communication to build aemergency communication And has made some breakthroughs in the construction of urban emergency linkage.
According to the staff of China Satcom, China Satcom is in ShandongWeifangUrban emergency linkage construction has become“Sample project”It is widely promoted.It was announced that China Satcom won the bid againQingdaoInformation about cluster communication construction.China Satcom digital trunkingCommunication networkBeijing, Shanghai, TianjinJinan, Nanjing, Qingdao, Weifang and other cities to achieve the application of government departments, ports, transportation, energy, logistics and other fields, and successfully“The tenth sessionNational Games”、“ShanghaiAPEC Meeting”、“Shanghai F1 Competition”、“Tianjin Asia Europe Finance Ministers' Meeting”、“Qingdao InternationalOlympic Sailing Competition”And other major conferences and events provided efficient and high-quality communication guarantee.
In terms of Olympic communications,China SatcomSubordinate Beijing Zhengtong CompanyResponsible for the construction of Olympic digital clusters in Beijing.In 2007, Beijing Zhengtong successfully held the "Two Sessions", "Municipal Party Congress"“World Taekwondo Championships ”And other activities to provide digital trunking dispatching communication support services.Beijing Zhengtong is ensuring digital trunkingCommunication networkPhase III expansionengineering constructionAt the same time of successful completion, we are accepting the support capability andservice level 23 Olympic test events.
China RailcomWith the help of the profound experience of railway cluster dispatching, efforts are made toCommunication marketCreate a new world.After China Railcom launched the "one swift" digital trunking serviceShenyang、ChangchunChongqing has established a commercial pilot network.China Railcom's digital trunking business has been widely used in the above three cities.
In addition, ChinaTietongAnd undertookqinghuangdaoCity“internationalWomen's FootballInvitational Tournament”Communication support, which is alsoOlympicAs part of the test event, China Railcom's "Yixuntong" digital trunking business will also be strictly tested.
Domestic and international technical wrestling
Group call, group callBroadcast call, emergency call, forced disassembly and insertion, and different priority levelsTechnology applicationThe foundation ofSystem security, reliability and extremely shortCall establishment timeEtc. has become the focus of cluster product competition.domestic marketThe competition is mainly reflected in the competition between foreign technology and domestic technology.
stayChina SatcomAt the booth, the staff of Beijing ZhengtongZhao YingTell reporters that the Olympic communications in BeijingCluster technologyAll are TETRA. After years of international application, TETRA has stability, security andRapid responseThe guarantee of the aspect has been recognized by many parties.For this reason, TETRA has become the only one used in BeijingDigital trunking technology。
China Satcom andChina RailcomAlso withZTECooperation to promote China's digital trunkingcommunications technologyDevelopment of GOTA.China Railcom has adopted a large number of GOTA systems, and the number of digital trunking commercial users has reached more than 30000.ZTEchairmanHou WeiguiSaid that ZTE would increase its efforts to invest in the development of GOTA digital clusters, fully solve the problems existing in the GOTA system, and fully supportChina SatcomFor government departments, industry users andOlympic GamesProvide more high-quality digital trunking communication services.
Performance improvement
GOTA digital trunking system
According to the introduction, domestic GOTADigital trunking technologyThere are some problems in the network, system, terminal and other aspects of the system in Tianjin, Jinan, Nanjing and other cities in the process of trial commercial use for more than three years. However, according toZTEAccording to the booth staff, after a detailed analysis of the causes of the problem, ZTE has drawn up a solution, which has achieved the expected indicators, and GOTA digital trunking system has achieved the whole network call response below 900msreaction timeAt the same time, the stability and security of GOTA's whole network operation have also been improved.
In addition, in order to cooperate with operators to develop various industry markets, ZTE's GOTA system has further developed API interfaces and customizedClient application, while providing general dispatching desk software, help all kinds of users develop dispatching with unique applicationsintegrated system 。
To be located
In addition to private network trunking communication, the reporter also found that some manufacturers exhibited public network based digital trunking communication systems, such asJin PengExhibited digital trunking based on TD-SCDMACommunication products。It is reported that Jinpeng is based oncdma2000 trunking communication system has also been running in Guangzhou for a long time.
However, some experts in the industry said that the public network based cluster communication has yet to be tested in terms of actual commercial use.Although public network trunking communication has the characteristics of low network construction cost and cheap terminal price, it is not the development direction of the whole trunking communication industry. Relevant experts said that its market positioning needs to be further clarified.
