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Fixed Wireless



The biggest buzzword in fixed wireless today is WiMAX. Despite some backers' heated promises to provide Internet access for your toothbrush at 400 miles, don't fall for the hype. When WiMAX begins to see greater deployment it may have an impact on the fixed wireless landscape. More on that later. For now, let's talk about some of the fixed wireless technologies that have been supplying network transport for some time.

Wi-Fi in the Backbone

Nearly 70 percent of network pros we polled currently running fixed wireless report that 802.11 products form the backbone of their networks. Two types of 802.11--a and g--provide a theoretical maximum of 54 Mbps and are available at a low cost from many distributors. An 802.11a/g bridge can serve as a link between the network main node and a remote location, and specialized antennas with high levels of gain, such as a yagi or parabolic dish, make the signal effectively stronger than if it had been transmitted from a standard patch or "rubber duck" antenna (the stubby rubber antenna you see on walkie-talkies and most Wi-Fi access points). As readily available, low-cost and highly adaptable as these systems are, why would anyone use anything else?

A few reasons. 802.11a/g products' limits in throughput and security may lead IT to consider other options for bridging and MAN (metropolitan-area networking) deployments. Although 45 percent of readers polled say they are most concerned about security, compared with 27 percent citing performance, the most significant limitation is that the protocols involved were created to support individual users in a point-to-multipoint topology, resulting in throughput levels that are, at best, only half the data rate because of network overhead, lack of signal strength, and various contention and interference issues. Wi-Fi links won't reach 54 Mbps and may miss that mark by a wide margin, especially if the endpoints are using noise-filled channels trying to avoid interference in the crowded 2.4-GHz band (for 802.11g) or the (as yet) less crowded 5-GHz band (802.11a). Because of less potential for interference and many more channels, 5 GHz is usually a better choice than 2.4 GHz for these links.

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