introduce 6 kinds of wireless LAN access technology, wireless LAN access technology mainly from various access technology and GSM access technology introduced wireless LAN access technology, unwind can finish Settings, there is nothing to it. Quickly entered the wireless world to come.
With the telecommunications market opening day by day, and the telecommunication positive digital, broadband change, integrated, personalized rapid development, each operator between the increasingly fierce competition. And competitive basis points lies in access resources competition, how fast, efficient and flexible, low cost provide customer need various business become operators of first consideration question. Wireless access to a certain extent satisfy the operator needs.
A wireless access does not need special for pipeline line laid, for some cable or cable laying areas cannot provides business access may, shorten the project time, save the pipe line investment.
A with access technology development, the wireless access devices can also solve data and voice and so on many kinds of business of access.
According to the regional traffic should increase or decrease flexiable adjusted bandwidth.
A can be convenient for business migration, the expansion. In makeshift business points in the application of advantage more apparent.
Commonly used wireless access in structures in general can be divided into two kinds, one kind is bureau end equipment through wireless Internet between way, equivalent to Repeaters. Another is by wireless access terminal user access bureau end equipment.
1, and wireless LAN access technology GSM access technology
GSM is a originated in Europe's mobile communication technology standards, is the second generation mobile communication technology. This technology is currently personal communication of a common technical representative. It USES is narrowband TDMA, allowing a rf  namely 'honeycomb'  simultaneously group 8 calls. GSM is 1991 came into use. By the end of 1997, has been operating in more than 100 countries, become the European and Asian actually standards.
GSM digital network has strong confidentiality and anti-jamming and timbre is clear, the stable, and with the call of large capacity, high frequency resource utilization, interface open, powerful, etc. Our country 90's in the 20th century introduced by the standard technology, had been using honeycomb is simulated moving technique, namely the first generation of GSM technology (December 31, 2001 China closed simulation mobile network). At present, China mobile, China unicom all have a GSM network, GSM mobile phone subscribers in 140 million above, as the world's largest mobile communication network.
2, and wireless LAN access technology CDMA access technology
CDMA namely code - divisionmultipleaccess abbreviations and translated into "code division multiple access (CDMA) packet data transmission technology", known as the 2.5 generation mobile communication technology. CDMA mobile phone has voice clear, it is not easy to drop words, transmission power, low and confidentiality strong wait for a characteristic, transmit power only GSM mobile transmit power of 1  60, known as "green mobile".
More importantly, based on the broadband technology of CDMA mobile communication in video applications made possible. CDMA and GSM is same, also is to belong to a mature wireless communication technology. With the use of a DivisionMultiplexing technology - GSM different is, CDMA not give every often the distribution of a certain frequency, but to make every channel use can provide the whole spectrum.
Therefore, CDMA digital network have the following advantages: high bandwidth utilization ratio and the larger network capacity, simplified network gauge change, call quality high, privacy and signal coverage is good, not easy to drop words, etc. In addition, CDMA system adopt coding technology, the coding 4.4 billion have kind of digital arrays, each handset coding also change, this makes the cloning only become the theoretically possible.
3, and wireless LAN access technology GPRS access technology Relatively originally GSM dial-up way circuit switching data transfer mode, GPRS is packet switching. Using the "group" technology, Internet users can from the pain of disconnection  situation would probably have to use the download software  NetAnts almost.
In addition, use wireless LAN access technology GPRS Internet method and WAP and different, use WAP Internet like in the home, first "Internet dial-up connection", while Internet after it was not at the same time use the telephone, but GPRS is superior, download data and call can be performed at the same time. Technically speaking, if simple for voice calls, might as well continue to use the GSM, but if there is data transmission requirement, had better use GPRS.
It put mobile phone application elevated to a higher level. Meanwhile, the development of GPRS technologies are also very "economy", because it only need to upgrade the existing GSM network can. GPRS USES is very extensive, including through mobiles and receive emails in Internet browsing, etc.
GPRS is the biggest advantage is: its data transmission speed the WAP can match. At present the GSM mobile network data transmission speed 9.6 K bytes per second, and GPRS reached 115Kbps this rate is commonly used 56Kmodem ideal rate  twice. Besides velocity superiority, GPRS 'em forever online' characteristics, namely customers to keep in touch with network.
4, and wireless LAN access technology CDPD access technology
CDPD access technology the greatest characteristic is transmission speed, the tallest communications speed can reach 19.2 KBPS. In addition, data security, as a result of the RC4 encryption technology, so security is relative taller; Positive and negative to channel key asymmetry, key by exchange center of master, mobile terminal login time, exchange center of automatic check old key replacement of the key once, a dynamic management.
In addition, because CDPD system is based on TCP  IP open systems, so we can easily access the Internet, all based on TCP  IP protocol application software can be used directly without having to change, Application software development is simple, The mobile terminal communications Numbers directly use the IP address. CDPD system also support the user handoff and hyper roaming, broadcasting and group oo-hoo, support movement speed of  h data users 100km with public data cable network and interworking.
5, and wireless LAN access technology fixed broadband wireless access (MMDS/LMDS) technology
Broadband wireless access system can use frequency band according to different division of Multi - for MMDS (any Multi - were ever Service) and LMDS (Local Multi - were ever Service) two old series, Chinese meaning called the Local multi-point Distribution business. This is a kind of microwave broadband technology, and is named "wireless fiber" technology.
It can be in more recent distance realize two-way transmission voice, data and video image, meeting television broadband business, and to support  IP and ATM, TCP MPEG2 such criteria. Adopt a similar cellular service to structure, a need to provide business area divided into several service area, each service with base station, base station equipment by point to the multi-point radio link and service area of client communication. Each service coverage for several kilometers to ten kilometers, and may overlap each other.
Because NMDS/LMDS has higher bandwidth and two-way data transmission characteristics, and it can provide various broadband interactive data and multimedia services, overcome traditional local loop bottlenecks, satisfy user high-speed data and image communication growing demand, so is to solve the problem of network access tool.
6, and wireless LAN access technology DBS satellite access technology
DBS technology also called digital broadcast satellite access technology, the technology USES the earth geosynchronous orbit communications satellite radio data sent to users will speed the receiving antenna, so it are also commonly called high rail satellite communication. Its characteristic is communication distance and expense and the distance is irrelevant, covering the area is large and not affected by geographic conditions, wide frequency band, large capacity, suitable for more business transmission, but to global customers provide large span and large scope, distance of roaming and flexible mobile communication services, etc.
In DBS system, a large amount of data by frequency modulated cream-and-green points or use satellites such as host of high-speed uplink channel and satellite transponders broadcast, the user through satellite antenna and satellite Modem receiving data, receiving antenna diameter general 0.45 m or 0.53 m.
As a result of digital satellite system has high reliability, unlike PSTN network using twisted-pair phone need more simulation of signal correction, so can make the download speed reached 400kbit/s, and practical DBS radio rate can reach the highest 12Mbit/s.
At present, the United States has can provide DBS service, mainly used for Internet access, one of the largest DBS network is hughes network system of the company DirectPC. DirectPC data transmission is not symmetrical, in the access the Internet, download speed for 400kbit/s, ascending rate for 3.36 kbit/s, although the rate than ordinary dial-up Modem improve a lot, but with DSL and CableModem technology is still cannot be compared.