Development status of trunking communication

TETRA (Terrestrial Trunking Wireless System) is a wireless trunking mobile communication system based on digital time division multiple access (TDMA) technology, and it is a digital trunking communication system standard formulated by ETSI. It is a special mobile communication wireless standard developed on the basis of digitalization of traditional large-area dispatching communication system.

TETRA digital trunking communication system can provide command and dispatch, data transmission and telephone service on the same technical platform. It can not only provide multi-group scheduling function, but also provide short data information service, packet data service and digital full-duplex mobile telephone service. TETRA digital trunking system also supports powerful DMO mode, which can realize authentication, air interface encryption and end-to-end encryption. TETRA digital trunking system has the function of virtual private network, which can make a physical network serve multiple unrelated organizations, with rich business functions, high frequency utilization, high communication quality and flexible networking mode. Many new applications (such as vehicle positioning, image transmission, mobile Internet, database query, etc. ) has been implemented in TETRA.

In recent two years, TETRA digital trunking system has been widely used in the world, especially in the European market. By the end of 65438+ in February, 2004, the total number of TETRA contracts worldwide was 6 15, an increase of 90% over the same period in 2003. These contracts belong to 70 countries around the world, of which Europe accounts for 75% of the total global contracts. The digital trunking market in Asia-Pacific and the Middle East is in a stage of rapid development, which also provides good market opportunities for it.

Judging from the current data, in the development of TETRA in various regions of the world, the number of contracts signed in the Asia-Pacific region has increased the fastest year-on-year, with a growth rate as high as139%; Followed by the Middle East, the growth rate reached114%; The growth rate of western Europe has also reached 1 10%.

In terms of the number of contracts, the top three countries that signed TETRA contracts in 2004 were Britain, France and the Netherlands-mainly in Europe.

In China, TETRA system is widely used in several digital trunking communication technology systems, mainly in government, railway, subway, aviation, airport, water conservancy and other departments.

TETRA has unique technical advantages and is very attractive to the private network of powerful departments. At present, its global users are mainly distributed in the fields of public security/transportation /PAMR/ public utilities/government/military/petroleum/industry, among which the public security and transportation departments account for more than 65% of the market. In the Asia-Pacific region, it is basically used in the fields of public safety/transportation /PAMR/ public utilities, with great market development potential.

However, at present, the external interconnection technology of TETRA network has not been fully disclosed, TETRA products from different manufacturers have not been fully interconnected, and there are still some problems in the interoperability of users and services between different networks and even roaming in different places. In addition, the system equipment procurement, network construction cost and terminal price of TETRA are high, which restricts the further development of TETRA to some extent. Iden (Integrated Digital Enhanced Network) is a digital trunking mobile communication system developed and produced by Motorola. Its predecessor is MIRS system, which was originally designed for cluster network applications. Therefore, in addition to commanding and dispatching services, it also has the functions of duplex telephone interconnection, data and short messages.

In terms of technology, iDEN has the following characteristics:

First of all, in terms of function, iDEN absorbs the advantages of digital cellular communication system on the basis of traditional dispatching communication and enhances the telephone interconnection function. Its wireless phone function is at the same level as personal mobile communication system, and the value-added services of digital cellular communication system such as short message service based on IWF, voice mail and circuit data are applied to iDEN system.

Second, iDEN can make efficient use of traditional spectrum. IDEN adopts the traditional 800MHz spectrum (806 MHz ~ 825 MHz, 85 LMHz ~ 870 MHz), which is widely used in trunking communication in all countries except Europe. IDEN can use discontinuous frequency points, which is convenient for operators to allocate frequency resources flexibly. IDEN divides a 25kHz physical channel into six channels through TDMA technology.

Thirdly, iDEN adopts the unique MI6QAM modulation technology, which makes the rate of each 25kHz physical channel (including six communication slots) reach 64Kbps, and at the same time makes the adjacent channel suppression reach more than 60dB. This efficient modulation technology ensures the * * * storage of digital and analog systems during the digitalization of trunking communication. The speech coding method of iDEN is 4.2Kbps VSELP, which can compress 6: 1.

Fourthly, the cellular structure improves the coverage capacity of the network. IDEN adopts 7×3 cell reuse mode, which divides a base station into sector cells, expands cell capacity and improves large-area networking capability. At the same time, the omni-directional base station mode can also be adopted, and the omni-directional cell reuse mode is 12× 1, which is gradually developed according to local conditions;

Fifth, cross-system scheduling communication can be realized.

At present, iDEN technology system is mainly used in digital trunking network system, and its main markets are America and Asia. In the United States, the iDEN system has been deployed in the United States, Canada, Argentina, Brazil, Colombia, Mexico and Peru. In Asia, iDEN network can be seen in Japan, South Korea, China, the Philippines, Singapore, Israel and other countries. Among them, the iDEN network operated by American Nextel Company (now merged with other mobile operators) is the largest and most developed iDEN network in the world.

IDEN network services have a wide range of users, including government agencies and all kinds of enterprise users, such as: construction industry, maintenance service industry, energy and electricity industry, commodity retail and wholesale, agriculture, forestry, mining, broadcasting and publishing industry, etc.

However, the iDEN system is exclusively manufactured by Motorola, and the interface is not open. At present, network equipment is mainly provided by Motorola, so the cost of system equipment procurement, network construction and terminal is relatively high. Moreover, due to the early research and development, although the technology is relatively mature, the ability to support new business is relatively weak. GOTA (Open Trunking Architecture) is a trunking communication system based on trunking network application proposed by China ZTE Corporation, and it is also the first digital trunking system based on CDMA technology in the world. With independent intellectual property rights in China, it has the characteristics of fast connection and channel sharing. As a * * * network technology, GoTa is mainly used in the * * * network cluster market. Its main characteristics are more conducive to operators to build a * * network cluster network, suitable for large-scale coverage, high spectrum utilization, and better meet the needs of * * network cluster networks and business applications in terms of business performance and capacity.

GoTa adopts the latest wireless technology and protocol standards adopted by the current mobile communication system, and optimizes and improves it, so that it can meet the technical requirements of the trunking system, and at the same time, it has strong network operation ability and business expansion ability to meet the future development needs of the trunking system.

The trunking services that GoTa can provide include: one-to-one private call and one-to-many group call; Special services, such as system paging, group paging, sub-group paging and special PTT service; Classify different traffic groups, such as permanent groups and temporary groups, and users can manage the members in their groups. In addition to trunking services, GoTa also has all new value-added services, such as SMS, location, VPN and so on. These services, combined with cluster services, can provide comprehensive services for group users.

GoTa successfully solved the key technology of trunking service based on CDMA technology. In order to carry out PTT communication on CDMA network without affecting the existing service function and performance of the original CDMA system, GoTa puts forward solutions around two key technologies: wireless channel sharing and fast link, so that the new trunking service will not adversely affect the traditional communication service and network resources. Compared with the traditional trunking communication mode, GoTa technology has the advantages of advanced technology, rich business, less investment, quick effect and low operating cost.

On March 19, 2004, ZTE GoTa Industry Alliance was launched, and terminal manufacturers such as Guanri, Youth Network and Southern Hi-Tech began to cooperate with ZTE to promote the development of GOTA industry.

At present, ZTE has cooperated with two basic telecom operators, China Tietong and China Weitong, to carry out commercial trials of GOTA digital trunking. In addition, it has won digital trunking projects in more than ten countries and regions such as Russia, Norway, Malaysia, Thailand, Egypt and Algeria, among which Norway and Malaysia are commercial networks.

Although iDEN and TETRA technologies are relatively mature at present, their prices are too high. GoTa has good cost performance, clear forward development track, strong multi-service value-added ability, good security, confidentiality and trustworthiness, but its maturity is relatively poor and needs time to improve. So in a certain period of time, TETRA, iDEN, GoTa, etc. There will be different basic market positioning in China market, and they will survive in the competition, and their future development will depend on the choice of market users. GT800 is another TDMA-based professional digital trunking technology proposed by Huawei with independent intellectual property rights in China. By creatively integrating and innovating TDMA and TD-SCDMA, we can provide high-performance and large-capacity trunking services and functions for professional users. Technological innovation is mainly reflected in the realization and promotion of cluster characteristics, and dozens of core patents of cluster technology have been formed at present.

The technical advantages of GT800 are mainly reflected in the following points:

1. Wide coverage. Due to the TDMA technology system, the transmission power of each channel of GT800 is constant, and the coverage distance is only affected by the terrain, so it can achieve wide coverage while enjoying the channel. With the increase of users, cell coverage is not affected, and all groups * * * enjoy the full coverage service area of GT800 network, which truly embodies the wide coverage, wide dispatching and wide communication of GT800 cluster * *.

Second, GT800 inherits the mature digital trunking technology system in the industry and realizes real channel sharing. There is no limit to the number of users in the group, and users will not interfere with each other, thus realizing real response.

3. dynamic channel allocation, which releases channels in voice gaps and allocates channels only when speaking, greatly improves the capacity of the system group, and ensures high-priority users to speak smoothly even under the capacity load limit; Fourth, provide 3G-oriented sustainable development capabilities. The first-stage GT800 system based on TDMA system can easily evolve to the second-stage GT800 system of TD-SCDMA, which fully embodies the design concept of protecting users' investment.

A few years ago, Huawei, Sachim, Bird, Eastcom, Amoi, Kejian and other six major communication equipment and terminal manufacturers at home and abroad jointly launched the "GT800 Digital Trunking Industry Alliance" to promote the development of GT800 digital trunking communication technology and products.