Implementation of Smart Antennas for Wireless LAN Systems

The IEEE 802.11 wireless LAN (WLAN) standard has achieved world-wide acceptance. However, current products have been excluded from greater adoption due to limitations that include range, capacity, high power drain, coverage dead spots, co-channel interference, and security. Smart antenna sys-tems have demonstrated significant promise to alleviate all of these problems (aside from security) while still remaining compatible with the 802.11 (b/a/g) standards. This paper discusses the history of smart antenna systems, including a brief overview of how smart antennas are being implemented by various companies in the cellular, fixed wireless, and wireless LAN spaces. The cate-gories of smart antenna systems are discussed, including a basic theoretical model of a typical smart antenna setup. Smart antenna implementations gen-erally can be categorized as either switched diversity, beamforming, sector-ization, Space-Division Multiple-Access, or MIMO systems. The reasons that smart antenna systems are not implemented more today are also discussed. This paper then examines the benefits that smart antenna systems provide, focusing on the benefits for WLAN systems. The benefits are analyzed for range, fading reduction, power drain, dead spots, and co-channel interference, and are shown to be significant.