In just the past few years, wireless LANs have come to occupy a significant niche in the local area network market. Increasingly, organizations are finding that wireless LANs are an indispensable adjunct to traditional wired LANs, as they satisfy requirements for mobility, relocation, ad hoc networking, and coverage of locationsdifficult to wire. As the name suggests, a wireless LAN is one that makes use of a wireless transmission medium. Until relatively recently, wireless LANs were little used; the reasons for this included high prices, low data rates, occupational safety concerns, and licensing requirements. As these problems have been addressed, the popularity of wireless LANs has grown rapidly.
In this section, we first look at the requirements for and advantages of wireless LANs, and then preview the key approaches to wireless LAN implementation.
Wireless LANs Applications
There are four application areas for wireless LANs: LAN extension, crossbuilding interconnect, nomadic access, and ad hoc networks. Let us consider each of these in turn.
LAN Extension
最近幾年，無(wú)線局域網(wǎng)開始在市場(chǎng)中獨(dú)霸一方。越來(lái)越多的機(jī)構(gòu)發(fā)現(xiàn)無(wú)線局域網(wǎng)是傳統(tǒng)有線局域網(wǎng)不可缺少的好幫手，它可以滿足人們對(duì)移動(dòng)、布局變動(dòng)和自組網(wǎng)絡(luò)的需求，并能覆蓋難以鋪設(shè)有線網(wǎng)絡(luò)的地域。無(wú)線局域網(wǎng)是利用無(wú)線傳輸媒體的局域網(wǎng)。就在前幾年，人們還很少使用無(wú)線局域網(wǎng)。原因包括成本高、數(shù)據(jù)率低、職業(yè)安全方面的顧慮以及需要許可證。隨著這些問(wèn)題的逐步解決，無(wú)線局域網(wǎng)很快就開始流行起來(lái)了。