Classification and comparative analysis of wireless access technology

Wireless access has cellular mobile phone system, digital cordless telephone system and point-to-point microwave system, and many other technical systems to choose from. So, in order to carry out the arduous task of our country Telecom universal service, operator chooses that kind of technical system to be suitable? In order to construct the wireless access network reasonably and efficiently, we need to objectively compare and analyze the operating environment of different technical systems.

Generally speaking, any radio system can be used for wireless access, but its applicability is a function of several factors. Cellular macro Mobile systems (such as SCDMA400, CDMA450, GSM900) are suitable for rural suburbs, high speed and medium traffic density, cellular micro-zone mobile systems (such as SCDMA1900, GSM1800) are suitable for urban, slow speed and high traffic density; Cordless pico-Zone mobile System ( such as PHS) is suitable for urban indoor, low speed and high traffic density. The criteria for assessing the most applicable systems are generally determined by the following factors:

User requirements: To consider the type of business and the density of traffic, but also consider its performance price than the majority of users can withstand.

Spectrum efficiency: To analyze the characteristics of different air interface technology system, especially its spectrum efficiency can support the growing requirements of users.

Radio coverage: To determine the availability of the appropriate radio spectrum for the system, and whether the actual hive size in the area can meet the user's distribution.

Network cost: To analyze and compare the cost of network infrastructure, the cost of users ' equipment, the cost of operation and the speed of reducing equipment price by large-scale production, the initial investment of the network is small and can be invested in stages. (Computer science)

Existing network: How to achieve the new wireless access system and operators to integrate the existing network features to make full use of the operators already have network resources and number resources.

Comparison of the applicability of several wireless access modes to rural communication

According to the above analysis criteria, the applicability of several wireless access modes in rural communication is compared as follows:

Analog Wireless access: Analog wireless access in the rural universal service played a role, but backward technology, low spectrum utilization, limited network capacity, network costs and high terminal prices, construction costs up to more than 3,000 yuan per line. In terms of system capacity, assuming that a local network area of 10000 square kilometers, has been used for village and village engineering FDMA standard 450MHZ analog wireless access system can only carry 15,000 users, continue to develop simulation system is impossible.

PHS and Dect:phs technology is "PHS", its intellectual property is in the hands of Japanese companies; DECT is a European cordless telephone system. Their base station covers a small radius, only dozens of to hundreds of meters, in the populated rural areas of the base station is obviously not realistic, so PHS and DECT not suitable for the solution of rural communication access means.

Satellite communications: The early establishment of the VSAT system is the provincial communication network, the end station is located in no telephone county and township level, as each end station must invest tens of thousands of U.S. dollars, the average cost per household up to 7000 yuan-10000 yuan, in the rural universal access can not be widely used.

gsm:gsm900 and GSM1800 system for the urban dense population of mobile communication design, because of high frequency, weak diffraction ability, small coverage, so in the rural construction network base station is relatively large, the investment is also larger, the user few conditions under the condition of high cost, terminal equipment more expensive; using TDMA technology spectrum utilization is low, While GSM is the European communication standard, intellectual property is controlled by European companies, if Thyristor also need to research and development.

CDMA: As a Code division multiple Access System, CDMA system has high spectrum utilization ratio compared with frequency division multiple access and time division multiple address. The CDMA800 and CDMA1900 system is designed according to the requirement of 2.5G mobile communication, and it also makes the system construction cost high and terminal expensive because of the high frequency in rural area. It is difficult to be accepted by rural users in the reality of the low income of rural population in our country. As for CDMA450, although the band is suitable for rural communication, but because it is the United States communications standards, intellectual property rights by Qualcomm company control, network infrastructure and terminal costs are still high, for our government limited.

SCDMA:SCDMA is a synchronous CDMA wireless access system developed by our country, and it is the technical means for the Ministry of Information industry to popularize in the village and village communication project. When wireless coverage is carried out in rural areas, the network is generally a large area system, and the coverage radius is generally considered above 20km. SCDMA integrated wireless access system from urban and rural universal services, based on the structure of the macro-cellular network, using advanced smart antenna and Synchronous Code division multiple access and Time division duplex mode, it provides a wireless access system with large coverage area, low cost per line, various terminals, and data bandwidth sufficient for most broadband applications.