Broadband Wireless access technology represents a new development trend of broadband access technology, not only the rapid opening of the network, simple maintenance, low-cost users, but also changed the traditional concept of local telecommunications services, the most suitable for new telecom competitors to carry out effective competition, It can also be an important supplement to cable access for telecom companies.
1 Business category editing
MMDS System
the MMDS system for 2.5ghz/5.7ghz. It uses advanced VOFDM technology to achieve wireless communication, in the building of cities with "multipath" to achieve a single carrier 6MHz bandwidth transmission rate up to 22mbit/s data access, high spectral efficiency, in the 2.5GHz band can reach 90% of the communication probability, in the 5.7GHz band can reach 80 % more than the communication probability.
sdhip Ring System
Microwave Sdhip ring system working in high frequency bands. In the past, more microwave SDH equipment was used in the point-to-point microwave relay transmission circuit. Now with the progress of technology, some companies have introduced the microwave SDH bidirectional ring network, with self-healing function, and the self-healing characteristics of the fiber ring, integrated with ADM, using a series of modems, to achieve QPSK-256QAM programmable, there are a variety of interfaces (g.703, STM-1, E3/t3, E1, Ethernet 10base-t/100base-t). At the same time, the construction of miniaturized structure equipment is more convenient than the previous microwave equipment, and in the case of frequency tension, this equipment can work in 13GHz, 15GHz, 18GHz, 23GHz and other frequencies, in the construction of metropolitan area Network can avoid 3.5ghz/26ghz wireless access to the frequency of fierce competition, The bandwidth of the 8x155m can be supported.
Multi-point allocation LMDs
local Multi-point assignment business LMDs. It works in the 20ghz~40ghz frequency band, the transmission capacity can be compared with the fiber, at the same time the wireless communication economy and ease of implementation, and other advantages. LMDS is based on MPEG technology, which is developed from the microwave video distribution system (MVDS). A complete LMDS system is composed of four parts, namely local fiber backbone network, network Operation Center (NOC), base station system and user-side equipment (CPE). LMDs is characterized by: bandwidth can be compared with optical fiber, the realization of wireless "fiber" to the floor, the available frequency bands of at least 1GHz, compared with other access technology, LMDS is the last kilometer of optical fiber flexible replacement technology, fiber transmission rate of up to GB, and LMDS transmission rate of up to 155mbit/s, stable second ; The LMDS can support all major voice and data transmission standards; LMDs work in the millimeter-band, 20ghz~40ghz frequency, the permitted frequency is 24GHz, 28GHz, 31GHz, 38GHz, of which 28GHz obtained more licenses, the band has a more relaxed spectrum range, the most potential to provide a variety of services.
Fixed Wireless access system
the types of air interfaces used are broadly divided into three categories: IP-based, ATM-based cell, TDMA-based time slot assignment. It has corresponding theoretical values and engineering achievable values for modulation, demodulation, error correction, reception sensitivity and spectral efficiency. Different modulation methods generally correspond to different error correction methods, in the wireless communication system, the error correction performance will directly affect the overall performance of the system, especially in the organization of multi-sector more to this point of full attention. However, there is no denying that the corresponding relationship between the modulation mode and the error correction mode in the actual construction network is very much biased with the theoretical value. Why is there a big difference between theory and engineering? The main reason is that it is impossible for any equipment to achieve ideal spectral efficiency when the band radiation is limited, because it is necessary to increase the roll-down router to prevent the system from interfering with the adjacent frequency system in addition to the bandwidth occupied. At present, there is a widespread exaggeration of the spectrum utilization, and there is an inconsistency of definitions, the values of different definitions sometimes differ greatly, which is more important when choosing a network device, so that the selected device cannot meet the requirements.
2 Business Hosting edits
in business hosting, the business of 3.5G system can be divided into two main categories: mainly based on transparent transmission of TDM Circuit basic business (base station transmission link and leased line business) and IP services, wireless access devices generally support both services, so that operators to provide users with differentiated service.
on the network management, authentication and billing, most wireless access equipment network management systems are based on the SNMP protocol platform, and the user authentication and billing is basically done by third-party equipment, the wireless access device itself can provide as many parameters as possible for the relevant equipment access and use.
due to resource constraints and the transmission characteristics of the 3.5GHZ device itself, antenna technology, an operator in the 3.5GHz band difficult to organize the same Metro multi-cell system, unless the base station has a larger choice of freedom, so in the network planning should be carefully considered, especially the choice of equipment must have a higher performance indicators.
Wireless access Technology
