1 preface
The rapid development of mobile communication service is mainly because it meets people's needs anytime and anywhere. The desire to communicate with anyone anywhere. Mobile communication is the only way to realize the ideal personal communication service in the future. Under the joint action of information support technology, market competition and demand, the development of mobile communication technology has advanced by leaps and bounds, showing the following major trends: data-based network services, grouping, broadband network technology, intelligent network technology, higher frequency band, more effective frequency utilization and convergence of various networks. Understanding and mastering these trends is of great practical significance to mobile communication operators and equipment manufacturers.
2. Data and grouping of network services
2. 1 wireless data-unlimited vitality At present, mobile data communication is developing rapidly and is considered as a main direction of mobile communication development. In recent years, there are two main types of mobile data communication. One is circuit-switched mobile data services, such as data bearing services of TACS, AMPS, GSM and HSCSD; In the GSM system. The other is packet-switched mobile data services, such as Motorola's DataTAC, Ericsson's Mobitex and GSM's GPRS.
At present, wireless data service only accounts for a small part of the total traffic of GSM network, but this situation will begin to reverse and change greatly in the next two years. After 1999, with the emergence of new high-speed data solutions such as HSCSD and GPRS, and becoming the new focus of data application, wireless data will become an increasingly important part of operators' business plans, which indicates a lot of business opportunities in the future.
(1) application-driven market
The main driving force of wireless data service lies in the application of users. Voice is a single and easily accepted service, but wireless data is different. The initial application of wireless data focused on professional markets such as traffic management. The target market of wireless data service in the near future is the user groups such as salespeople or field engineers. Accumulate the experience of wireless data from the application of these early targets and benefit from it.
In the past ten years, the traditional way of life has changed rapidly, people move more frequently, the boundaries between professional and personal life have become blurred, and people need to access important information anytime and anywhere. This lifestyle change that happens to users will become an important factor to promote the development of wireless data services.
(2) the influence of the Internet
Like other communication fields, one of the most important driving forces of wireless data service comes from the Internet. According to recent research, the number of Internet users in Europe will double in the next two years. In China, the annual growth rate of Internet users will be as high as 300%. Obviously, users' demand for surfing the Internet during exercise will increase.
In order to meet the demand of accessing the Internet, a global open protocol-Wireless Application Protocol (WAP) came into being. WAP provides an open and universal standard for transmitting Internet information and value-added services to mobile terminals, and realizes the bridge between IP and GSM networks. It is the standard for manufacturers to accelerate market growth, avoid network cutover and protect operators' investment. WAP ensures that any GSM mobile phone compatible with WAP can work.
(3) the development of data rate
The maximum GSM data rate provided by GSM bearer service can only reach 9.6 kbit/s, and the high-speed circuit-switched data (HSCSD) technology introduced by 1998 will achieve a data rate of 57 kbit/s, which is very suitable for applications requiring continuous bit rate and small transmission delay, such as conference TV, e-mail, remote access to enterprise LAN and wireless images. GPRS, commercialized in 1999, is the first GSM packet data application, which will achieve a data rate exceeding 100 kbit/s ... It is very suitable for short "burst" services, such as credit card authentication, remote measurement and remote transaction processing. EDGE (Enhanced Data Rate GSM Improved Mode) uses an improved GSM modulation mode to achieve a data rate of over 300 kbit/s. EDGE will be particularly beneficial to GSM operators. They can not only win the third-generation mobile communication business license, but also provide competitive broadband data services.
2.2 Personal multimedia communication-the direction of network evolution
The pursuit of voice communication anytime and anywhere made the early mobile communication successful. The commercial value and user market of mobile communication have been proved, and the global mobile market is growing at an extraordinary speed. The next stage of the development of mobile communication is the transfer to wireless data and even personal mobile multimedia. This progress has already begun and will become an important growth point in the future. Personal mobile multimedia will provide unimaginable and perfect personal business and wireless information according to the location, which will have an impact on all aspects of people's work and life. In the personal multimedia world, voice mail and e-mail are sent to the mobile multimedia mailbox; Short messages will become electronic postcards with photos and videos; Voice calls will be combined with real-time images to produce a large number of visual mobile phones, and mobile Internet and World Wide Web browsing will also be realized. Applications such as wireless conference TV will be everywhere, and e-commerce will flourish. For sports users, there are also various email and entertainment services anytime and anywhere.
3 broadband network technology
In the history of telecom industry, mobile communication may be the fastest developing field in technology and market. There is an interactive relationship among business, technology and market. With the increasing demand of users for data and multimedia services, network services are developing towards data and grouping, and mobile networks are bound to develop towards broadband.
By using telephone switching technology and cellular radio technology, the first generation of analog mobile phones was born in the late 1970s. AMPS (North American Cellular System), NMT (Nordic Mobile Phone) and TACS (Omni-directional Communication System) are three main narrowband analog standards. One of the great achievements of the first generation wireless network technology is to cancel the subscriber line connecting the telephone and the network. For the first time, users can wirelessly answer and make calls anywhere.
The second generation system introduced digital radio technology, which provided higher network capacity, improved voice quality and confidentiality, and introduced seamless international roaming for users. The second generation digital wireless standards in the world market today, including GSM, MMPS, PDC (Japan Digital Cellular System) and IS95 CDMA, are still narrowband systems.
The third generation mobile system IMT-2000 is a real broadband multimedia system, which can provide high-quality broadband integrated services and achieve seamless global coverage. After 2000, the demand for narrow-band mobile telephone service is still great. However, driven by the demand for high-speed data communication and multimedia communication such as the Internet, broadband multimedia integrated services will gradually increase. From the perspective of seamless coverage of future information highway construction, broadband mobile communication will become more and more important as a subset of the entire mobile market share.
The third generation system is expected to be put into commercial use in 2002.
The changes from the second generation to the third generation system are not as great as those from the first generation analog network to the second generation digital network. According to the current technical development status and trend, the second generation system will gradually transition to the third generation system. In this evolution process, the data rate that the mobile network can achieve will be gradually upgraded: the data rate that the GSM bearer service can provide is 9.6 kbit/s, the commercial HSCSD technology in 1998 has achieved the data rate of 57 kbit/s, and the GPRS introduced in 1999 will achieve the data rate of more than100 kbit/s. EDGE technology to be launched in 2000 will achieve a data rate of more than 300 kbit/s. After 200 1 year, the third generation system will achieve a data rate of 384 kbit/s on the WAN and 2 mbit/s in the office and home.
4 Intelligent network technology
The increasing demand for mobile communication and the wide application of new technologies in mobile communication have promoted the rapid development of mobile networks. Mobile network has gradually developed from simple transmission and exchange of information to intelligent storage and processing of information, and mobile intelligent network has also emerged. Mobile intelligent network is a kind of network that attracts intelligent network functional entities in mobile network to complete intelligent control of mobile call. It is an open intelligent platform, which enables telecom operators to provide all kinds of new telecom services needed by customers conveniently, quickly, economically and effectively, and enables customers to have stronger control over the network and obtain needed information conveniently and flexibly. The mobile intelligent network achieves the above objectives by separating switching from services, establishing centralized service control point and database, and further establishing centralized service management system and service generation environment. Through intelligent networks, operating companies can optimize their networks and accelerate the generation of new services; We can design services according to customers' needs, open the network to other service providers and increase revenue.
The research of mobile intelligent network began as early as 1995. At the beginning, there was no specific standard agreement. Each manufacturer has formulated its own standards and done a lot of research work, such as Alcatel, Nortel, Ericsson and so on. These works have accumulated experience for the formation of the final mobile intelligent network standard.
At the end of 1997, CTIA formulated the first mobile intelligent network standard protocol-is-41d protocol. 1998 1 10 In October, the European Telecommunications Standards Institute (ETSI) introduced the CAMEL protocol (customized application of advanced logic in mobile communication) in the GSM phase2+ phase, and the version at that time was Phase 1. 1in April, 1998, ITU-T described the functional entity of mobile access in the newly launched intelligent network capability set -2 standard, which was called CAMEL phase2 standard.
With the evolution of mobile network to the third generation system, the degree of network intelligence is constantly improving. Intelligent network and its intelligent services are the basic conditions of personal communication in the future.
5 Higher frequency band
From the first generation of analog mobile phones, to the second generation of digital mobile networks, and then to the future third generation of mobile communication systems, the wireless frequency band used by the network follows a development trend from low to high. The frequency band of NMT, the first simulation system with international roaming function, which was born in 198 1, was 450MHz, and the NMT was changed to 900MHz at 1986. At present, the frequency band of domestic analog TACS system is also 900 MHz. In the second generation network, the initial frequency band of GSM system is 900MHz, and that of IS-95 CDMA system is 800MHz. In order to improve the capacity of GSM system fundamentally, 1800MHz system appeared in 1997, and GSM 900/ 1800 dual-frequency network became popular rapidly. The third generation system IMT-2000, which was put into commercial use in 2002, is positioned in the 2GHz band.
6 More efficient use of frequency
Radio frequency is a valuable resource. With the rapid development of mobile communication, the contradiction between limited spectrum resources and the rapidly increasing number of mobile users has become more and more acute, and the phenomenon of "serious frequency shortage" has appeared. The way to solve the problem of frequency congestion is to adopt various effective frequency utilization technologies and develop new frequency bands.
The early cellular mobile communication system of analog system adopted frequency division multiple access (FDMA), which mainly realized the effective use of frequency through technologies such as multi-channel utilization, frequency reuse and channel narrowband. With the development of business, the simulation system has been far from meeting the needs of users. Digital mobile communication has greater capacity than analog mobile communication. With the same frequency division multiple access technology, the digital system needs fewer carriers, so the frequency reuse distance can be smaller and the system capacity can be larger. Moreover, digital mobile communication can also adopt time division multiple access or code division multiple access technology, and the system capacity is 4-20 times larger than that of analog frequency division multiple access system.
As the most representative and mature digital mobile communication system, the development of GSM is an evolutionary history of frequency efficient utilization technology. GSM adopts time division multiple access system, and the effective use of its frequency is mainly realized by the continuous upgrading of frequency reuse technology. From the traditional 4×3 mode to 3×3, 1×3, MRP, 2×6 and other new multiplexing technologies, the frequency reuse density is gradually increased, the spectrum efficiency is rapidly improved, and the capacity of GSM system is gradually released. 65438-0995 Is-95 CDMA (narrowband) system put into commercial use, which is famous for its advanced wireless technology and large capacity. Based on spread spectrum technology, it distinguishes the signals of different users through different coding sequences. If multiple CDMA signals overlap each other in frequency domain or time domain, theoretically, the spectrum utilization rate of CDMA system is higher than that of GSM system, and the network capacity is larger. At the same time, CDMA system has certain overload capacity, that is, the system has soft capacity. WCDMA (Wideband Code Division Multiple Access), as the mainstream wireless access technology of the third generation mobile communication system in the future, can make more effective use of radio frequency. It adopts technologies such as hierarchical cell structure, adaptive antenna array and coherent demodulation (two-way), and the network capacity can be greatly improved, which can better meet the development requirements of future mobile communication.
7 The network tends to be integrated and unified.
7. 1 Structure of the Third Generation Mobile Communication System
The main goal of the third generation system is to integrate all networks including satellites into a unified system, which can replace many network functions, provide broadband services and achieve seamless global coverage. In order to protect the investment of operating companies in the existing network facilities, the evolution of the second-generation system to the third-generation system follows the principle of smooth transition. The existing second-generation systems such as GSM, D-AMPS IS- 136 will all evolve into the core network of the third-generation system, thus forming a core network family, and different members of the core network family will be connected into a whole through the NNI interface, thus realizing global roaming. On the periphery of the core network family, a huge wireless access family is formed, and almost all existing wireless access technologies and third-generation wireless access technologies such as WCDMA will become its members.
7.2 Future Network Architecture
The development of technology, the change of market demand, the intensification of market competition and the relaxation of market control policies will accelerate the integration of computer networks, telecommunications networks and television networks, and broadband IP technology will become the supporting point and combining point of the integration of the three networks. The future network will be broadband, intelligent and personalized, forming a unified integrated broadband communication network, and gradually evolving to the core. A framework consisting of a backbone layer and eight layers separates business from network.
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