Fixed wireless is also popular for providing temporary network connections, particularly when disaster strikes. Much has been written about the role fixed wireless played in restoring communication services to lower Manhattan following the terrorist attacks on the World Trade Center. Indirectly related to those applications are installations where fixed wireless is installed in conjunction with terrestrial links as a redundancy mechanism to ensure high availability.
Cost vs. Benefit
We'll admit that, as appealing as fixed wireless is, guided media--most often fiber--is almost always a better solution in terms of raw performance and reliability. But many times it's difficult or impossible to get fiber to a facility, either across the street or across town. That's when most organizations turn to leased-line services, usually T1 or T3 links.
A recent study by Proxim Corp. of 18 urban and suburban areas in the Eastern, Midwestern and Western United States showed that the nationwide monthly average cost of a T1 local loop circuit is $382, while a T3 circuit runs $3,550 (see "Make Your Case: Determining Real ROI"). At those prices, many fixed wireless offerings can pay for themselves in less than one year. That's the kind of compelling ROI that makes bean-counters sit up and take notice.
You can get many a fixed wireless system for less than $1,000. Most of these operate at 2.4 GHz and leverage commodity WLAN chipsets to deliver a maximum data rate of 11 Mbps. While these systems can be appealing, they often lack features important for enterprise implementations, including Power-over-Ethernet and flexible management and monitoring capabilities. In addition, because they're based on LAN protocols, they tend to require higher overhead, resulting in throughput that is as low as half the stated rate. Finally, the duty cycle of these products often fails to meet enterprise standards.
That's why many enterprise- and carrier-grade point-to-point products are migrating toward the 5-GHz bands. These systems are typically designed from the ground up for fixed wireless applications. As such, their feature sets, performance and overall reliability are better than lower-cost alternatives. The downside is that many of these systems will cost more than $10,000, though lower-cost options are starting to emerge.
When considering total system cost, factor in not only the cost of the wireless bridges and antennas but costs of components, installation charges and maintenance required for a production system. In the past, system integrators have charged a healthy premium for installation and maintenance, though the trend these days is toward self-installation, at least in enterprise environments where adequate expertise exists (for particulars on six 5-GHz systems see "The Point-to-Point of Wireless Bridging").