Research On The Key Technologies Of Smart Antenna In Wireless Local Access Network

WLAN (Wireless Local Area Networks) is a system by radio frequency technology to transferdata, which can achieve Ethernet or token network’s functions but not in the traditional cable.WLAN is convenient, economical, easy extension, high transmission rate and anti-interference,which makes up the deficiency of the wired network effectively, and extends the network. Smartantenna is constituted by antenna array which is segregative in space. It processes signal by usingdigital signal technology and according to different criteria, and generates space directional beamdynamically, so that the main beam of the antenna is at the desired user signal direction of arrival,and the side lobe interference signal arrival direction of alignment, which can achieve efficient useof mobile user signal and remove or suppress the interference signal.Although WLAN has been widely used because of its convenience and high transmission rate,its coverage is limited compared with cellular network which support mobility across wide areanetwork; WLAN is a shared medium, and it will split the throughput into several parts, and will loss50%by radio data transmission, thus its the capacity is limited; because the WLAN operating in theunlicensed bands, so they are more susceptible to other technology operating at the same frequencyband (such as Bluetooth) interference. The smart antenna technology can improve the SINR(Signal-to-Interference and Noise Ratio), and improve the system capacity, which expands hemaximum coverage area, and reduces the transmission power of mobile station, so it was introducedinto the WLAN. But the traditional IEEE802.11protocols works based on omnidirectional antenna,so the use of MIMO smart antenna in WLAN presents a lot of advantages because of its direction,and also brings some problems.Therefore, research on MIMO smart antenna technology for WLAN environment is carried outin this thesis, the above problems are analyzed, and the main work is as follows:First of all, the basic content of the wireless local area network and smart antenna, and theapplication of MIMO smart antenna in WLAN are outlined.Secondly, based on MIMO smart antenna wireless LAN environment, this thesis analyses how toreduce the hardware cost and burden of the signal processing by the appropriate algorithm inmaintaining power system. At the same time, this thesis introduces three kinds of algorithms in theindustry, and analyzes two kinds in detail.Thirdly, combining with the practical work, according to some characteristics of WLAN and smart antenna, taking MIMO smart antenna in the rural areas of outdoor type WLAN basestation for example, by the practical test result shows that the MIMO smart antenna can effectivelyenhance the coverage and throughput in wireless local area network.Finally, this thesis summarizes the application of MIMO smart antenna in WLAN, in themeanwhile, forecasts the trend of its development, and points out the technical challenges in thedevelopment of application in the future.