Forget 802.11(b)

June 1, 2001
The nature of the radio frequency data communications spectrum demands that industry move on to less busy frequencies when the air gets thick with messaging.

Forget 802.11(b)

At least, that's the advice of some technical gurus and marketing shills. And, for once, these two diametrically opposed groups not only agree, but might even be right — as shocking as that is.

Some of you may need to understand IEEE 802.11(b) before you can forget it. Sound a bit crazy?

Well, only when you understand it does forgetting it make sense.

IEEE 802.11(b) (and its root document 802.11) is the standard for interoperability of unlicensed 2.45 GHz wireless LANs. This was a huge step forward — getting radios from different manufacturers to actually recognize and communicate effectively with each other. 802.11 established throughput speeds up to 1 Mbit/sec. The 802.11(b) standard raised the bar, and products are now available with effective throughput of upward of 11 Mbit/sec.

There is still a difference between frequency-hopping spread spectrum (FHSS) and direct-sequence spread spectrum (DSSS) systems that no standard will bridge, but the bottom line is that both are relatively effective at tolerating radio frequency and electromagnetic interference (RFI/EMI).

The Wireless LAN Interoperability Forum (WLIF) has established an independent compliance testing program (dubbed WiFi for Wireless Fidelity) to certify WLAN products as Ethernet and 802.11 compatible. With these standards in place and use of WiFi-certified products, you can be assured of hardware compatibility and relatively straightforward implementation.

What’s wrong with that?

The problem is neither the technical standards nor the functionality of WiFi products.

The problem is the overall success of 2.45 GHz products. More and more products — including personal area networks such as Bluetooth, cordless phones and even microwave ovens — operate in the 2.45 GHz range. This proliferation of conflicting signals can, in some environments, produce enough “clutter” to degrade system performance, although one commentator claims that 2.45 GHz systems “degrade gracefully.” Whatever that means.

Some are not so kind in their opinions of this band of the spectrum. One system developer has asserted that, because the band is unregulated, sooner or later, it will get filled up. “It will be perceived as a garbage band, and then we’ll move to 5 GHz.”

In fact, some industry sources predict that within three years, some companies will have to dump their 2.45 GHz radios and move to 5 GHz.

Hence, the advice to “forget 802.11(b).”

What to do?

Learn about IEEE 802.11(a) — the standard for5 GHz radios. Systems are now available, and more are coming, which build on the benefits of 802.11(b)-compliant systems but operate in the more rarefied air of 5 GHz.

How long 5 GHz will remain “uncluttered” is uncertain, but it’s sure to be longer than 2.45 GHz.

Among the current benefits of 802.11(b) are wide product availability, reliability and relatively low cost (PC card WiFi modems can be had for less than $100). But if you have to replace everything within three years, those may not be real benefits.

Do you really need to forget about 802.11(b)? Some suggest having a site survey performed to determine whether 2.45 GHz is feasible. Given the current rate of advances in WLAN technology, you may want to replace everything in five years anyway (after you’ve amortized the costs) to take advantage of newer, even higher-speed systems. But if your environment shows signs of RF “clutter,” a 5 GHz system probably makes more economic and practical sense.

Bert Moore

contributing editor

[email protected]

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