【正文】 Interpretation of three basic elements, and antenna. (4) the UWB: Ultra Wideband, UltraWideband technology. UWB munication is also known as carrierfree baseband munications, and is almost fully digital munications systems, RF and microwave devices need very little, so you can reduce the plexity of the system, reducing The merits of wireless technology (A) WLAN technology WiFi technologies and products are already quite mature, and mass production. The technology for the wireless LAN as an extension of wired works, broadband applications for the particular location, even though the WiFi technology is widely used, but it is still in the security there is a certain security risk, the WiFi uses a radio frequency (RF ) through the air to send and receive data. Since wireless works use radio waves to transmit data signals, are very vulnerable to attacks from outside hackers can easily steal data within the coverage of the waves and even into the unprotected internal LAN. (B) analysis of WiMax WiMax is a stateoftheart technology, the introduction of relatively late, there are small frequency reuse, the use of the problem of low, but only recently standardized, largescale promotion of the technology also need to practice the test. From the application prospects of the technology can meet online in a wide range of requirements, coverage can include outdoor and indoor, can be a large area of coverage, or even a small number of base stations can be achieved throughout the city coverage. WiMax due to its advanced technology and ultralong transmission distance, has been the industry optimistic about the future direction of development of mobile technologies, and provides excellent last mile Inter access services. (C) of WMN technology WMN is being studied in the technology, bined with the characteristics of the various technologies continue to study different aspects of integration and not a mature product line to support largescale application of this technology. The application prospects of WMN in this emerging work not only has a broad application space for wireless broadband access in other areas such as the bination of data, the image acquisition module can monitor or data acquisition of the target object, and is widely applied to detect and other fields. With the other technology is constantly updated sound of WMN better with integration of plementary, so as to be able to exceed and play their respective advantages. (D) 3G technical analysis 3G 1996 standards, 2021 to plete the upperlayer protocols, including the plete formulation of standards. 3G work deployment with considerable practical experience, theory of a plete sets of building a work, including work link budget, the model budget and simulation. From the mercial prospects of 3G in some areas has been a largescale mercial applications, such as many European countries, Japan, Korea and so on have been building a 3G work. 3G technology has entered the practical stage, there are many countries and regions are under construction or will be building a 3G work. (5) on LMDS technical analysis Local Multipoint Distribution business systems, LMDS is a pointtomultipoint fixed broadband wireless access technology, its operating frequency to 20 GHz above, the use of millimeterwave transmission, within a certain range of digital duplex voice, data, Inter and video services, it is a very good broadband fixed wireless access solutions. In the optimal case, the distance up to 8 km。 However, due to rainfall because the distance is usually limited to km. Works sector or base station equipment to the ATM backbone work baseband information modulated RF signal transmitted out CPE in its coverage area to receive and RF signal to restore ATM base band signal, without the need for Each user specifically laying fiber or copper, to achieve bidirectional symmetrical highbandwidth wireless transmission. (6) MMDS, technical analysis MMDS The main drawback is blocking the signal quality is vulnerable to changes in the weather, the available frequency band is not wide enough, no more than 200MHz. Second, MMDS is very strict requirements on the transmission path. The modulation technique used by MMDS phase shift keying PSK, (including BPSK, DQPSK, QPSK) and quadrature amplitude modulation QAM modulation technique, and can not do the nonlineofsight transmission is difficult to promote the use of plex urban environment. In addition, MMDS is no uniform international standards, the manufacturers of the equipment patibility issues. (G) trunking technology Digital trunking system has many advantages, its spectral efficiency has greatly improved, can further improve the user capacity of the cluster system。 it increases the ability to signal antifading channel, changed for the better quality of wireless transmission。 developed digital encryption theory and practical techniques for digital systems, confidentiality, have greatly improved. Digital trunking mobile munication system provides multiservice, that is in addition to the digital voice signal, but also can transmit digital, image information. Transmission within the work is a unified digital signal, therefore greatly improve the service functions of the cluster work. (H) pointtopoint microwave technology The main advantage of microwave transmission in the following aspects: First, it can reduce the operator39。s operations. Compared to leased lines, microwave systems, as long as a year or so can be recovered. Second, the microwave transmission system deployment simple and fast. Compared with the traditional means of transmission, the advantages of rapid deployment to meet the needs of the development of new business. Third, the current microwave products for the future development is to protect, for new business and new demands of t