Alternatives to 2.4-GHz systems run into bandwidth, range and interference problems

Alternatives to 2.4-GHz systems run into bandwidth, range and interference problems

In weighing your options on wireless LANs, it is important not to confuse them with wireless metropolitan area networks or cellular telephone networks.

These systems generally require expensive infrastructures and provide much slower data rates than the 1-Mbps to 11-Mbps throughput that wireless LANs can generate.

Also, don't confuse wireless LANs with LAN-to-LAN bridges.

High-speed wireless bridges replace the cables used to connect separate LANs across a campus, city or hard-to-reach area where a wired solution is not feasible. Many of the wireless LAN manufacturers listed in this guide also make wireless bridges; other wireless companies specialize exclusively in bridges.

That said, there are some bona fide wireless LAN options to consider along with 2.4-GHz systems.

First are those that operate in the 900-MHz and 5.7-GHz bands.

Along with 2.4-GHz systems, these also communicate in the unlicensed Industrial Scientific Medical bands and require no site licensing for general use.

But although 900-MHz systems have been popular in the past, the band's small size overcrowds it, especially in densely populated areas.

The 5.7-GHz frequency band offers potentially high data rates, but products in this frequency range are still experimental and offer challenges in range and power consumption.

Other wireless LAN alternatives include infrared and UHF, or narrowband. Infrared is an invisible radiation band existing at the lower end of the spectrum and is commonly used for commercial applications such as TV remote control devices.

Stops short

Infrared transmissions aren't subject to electromagnetic or radio frequency interference.

But IR signals can't penetrate solid objects such as walls or doors, and the maximum range is usually about 50 feet.

UHF technology operates in the 430-MHz to 470-MHz or 800-MHz spectrums and offers the benefits of relatively long-range transmissions'several miles'and low operating costs.

But the interference potential with other radio frequency signals is high, and throughput tends to run no higher than 19.2 Kbps'too slow for many advanced network systems with more than one or two users.

'J.B. Miles

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