802.11b's Dirty Little Secret

Introduction

802.11b has gained wide acclaim as the most popular wireless local area networking standard in the corporate world. It is also the standard in the Macintosh world, where it is called AirPort. However, in our tests, and in discussions with others, we've uncovered what can best be called its dirty little secret: the limited range of the most popular 802.11b solutions and frequently encountered interference problems makes them all but unusable in many environments, where networking over distances of 50 feet or more is important.

Orinoco  802.11b

In one of our first tests, we attempted to network two computers with Lucent Orinoco WiFi cards: one upstairs and one downstairs in an 1100 sq. ft, two-floor condominium. Although we were able to network the machines, the signal quality indicators typically ranged from "poor" to "fair" and often indicated interference. In contrast, a pair of Intel AnyPoint 1.0 (HomeRF) wireless networking cards consistently showed signal quality across this distance as "excellent."

AirPort

On the MacDiscussion forums, a user named "Terry" remarks on similar problems on the Macintosh platform, which typically use Apple's Airport cards (reportedly, licensed from Lucent Technology's Orinoco division). He says, "until Apple can give AirPort decent range, there's no point in extending its applications: my AirPort base station is 42 feet straight-shot down a hall, through one wood door, to my big-screen TV room, where i also like to do some computing on my TiBook [PowerBook G4]. But the computer can't pick up the signal there, loses it halfway down the hall. Nor can it pick up the signal in my bedroom, about the same distance in a different direction. Or on my front patio, same distance. Or...or more."

To be fair, some of these problems are attributable to the design of the Titanium PowerBook G4, which most users find has a more limited wireless network range than most other Mac models. Still, however, the problem persists to an unacceptable degree even when cards with external antennae are used.

The AppleCare Knowledge Base describes potential sources of interference as follows:

• Microwave ovens: Placing your computer or an AirPort Base Station near a microwave oven that is in use may cause interference.
• Direct Satellite Service (DSS) RF leakage: The coax cable that came with certain types of satellite dishes may cause interference. Obtain newer cables if you suspect RF leakage.
• Certain electrical devices such as power lines, electrical railroad tracks, and power stations.
• 2.4 GHz phones: Cordless telephones that operate in this range may cause interference with AirPort communication when used. There are also other devices that operate in the 2.4 GHz range that could cause interference. If you are having issues with your phone or AirPort communication, use the AirPort Utility and change the channel frequency of your AirPort Base Station.
• Metal objects: If possible, move metal objects or change the placement of the Base Station so the path between your AirPort equipped-computer and the Base Station is free from metal objects that may cause interference.

It also lists effect of various home and office elements such as concrete, bricks and plaster on 802.11b communication. Interference results in a decrease in the range of contact with the base station and/or a decrease in the rate of data transfer.

What's Ahead

And if you think this problem is likely to be addressed in the next generation of products.... don't hold your breath. ZDNet writes that there are fears that 802.11a, a higher speed (54Mbps) variant of the technology might be less useful than 802.11b because it has a shorter range. Meanwhile, yet another 802.11 variant, dubbed 802.11g is also being touted as a future replacement for 802.11b. Read more....

However, an article in the March 2002 edition of Net Worker asks "Is 802.11 ultimately unfit for the home?" notes several advances that help to address the interference and security issues that have so far plagued the 802.11b standard. New devices such as the Orinoco AP-200 access point will support an upcoming 802.11i security standard (expected by September; does anyone else find the number of 802.11 name variants getting confusing?); via a free software download designed to stop packet sniffer programs such as 'AirSnort' that have poked holes in 802.11b network security for some users. Other advancement, notes Net Worker, include  new features designed to address interference problems caused by microwave ovens and 2.4-GHz cordless phones. Dynamic fragmentation technology chops off the packets of the data transmission and fits them into the gaps the microwave leaves open between bursts of energy. Dynamic cordless phone avoidance allows the AP-200 to scan the frequencies for a cordless phone transmission and select a free channel. Similarly, dynamic channel selection lets the AP-200 "listen to the air" before it picks a channel on which to transmit data. Unfortunately, the proprietary nature of these advances built into the AP-200 means that you have to use Orinoco adapters in all your PCs to get the benefit. We fully expect other manufacturers to offer similar improvements, but, for now, these issues serve to underscore what some are calling 802.11b's Dirty Little Secret.