Ask Dr. Protocol
Tips and Advice On Networking, Communications, And The Meaning Of Life

Q: Dear Dr. Protocol, what do you hear about the 802.11g wireless LAN standard that's about to be approved? I understand this new annex for the 2.4-GHz band supports the same data rates (up to 54-Mbit/s raw channel capacity) as its 5-GHz counterpart, 802.11a. Sure, there are only three channels available at 2.4 GHz, and there is some interference from other equipment, but wouldn't the less expensive equipment work fine for most applications?

I have a friend in the chip industry (actually chip testers for OEM) that says they are dropping "A" and ramping up BIG TIME for "G". What gives anyway?
- Doug D., San Jose, CA

A: Doug, I'm not sure what gives, except that there is a big tug-'o-war going on. From what I've been able to glean from the controversy, the arguments are:

On the pro side, 802.11a has:

1. Lots more channels - This is important in offices and apartments where you've potentially got lots of networks living in close proximity to each other, or one big network with lots and lots of subscribers.
2. Less interference from traditional sources - microwaves, cordless phones, etc.

But it also has:

1. Less range - 802.11a's 5-GHz signal does not carry as far, and does not penetrate walls as well as its 2.4- GHz.
2. A more expensive (at least for the next year) bill of materials to make a radio.
3. Only one vendor (Atheros) making a commercially-viable chip set, and it had some problems. But they are mostly taken care of in the second spin of the silicon.

(Note: (2) and (3) will change by the end of the summer as IceFyre, Bermai, TI, Broadcom, and several others weigh in with their 802.11a offerings - some of which claim to be equal cost, or less expensive than current 802.11b/g chip sets.

On the other hand, 802.11g has:

1. Better range at a given power level.
2. Lower cost chip sets (at least for the moment.)
3. Compatibility with existing 802.11b equipment found in homes and public infrastructure.

But, the downsides are:

1. It will not be great for high-subscriber-density areas.
2. If 802.11g is set up to be compatible with 802.11b systems, it loses much of its speed advantages whenever an 802.11b unit is in the area. (If invoked, the backwards-compatible feature forces the system to use the older, much less efficient 802.11b handshake protocol, and to transmit its beacon information at 1-Mbit/s data rate so that all radios can hear and respond) This is an important and often neglected issue.)

And so the argument rages. My crystal ball is in the shop at the moment for its annual alignment, but I will prognosticate that 802.11a will eventually win out for commercial applications. From this point on, any smart public infrastructure provider will offer dual-band (2.4- and 5-GHz) access points to make sure everyone can reach the network. There are already several manufacturers that are making reasonably-priced nodes that run on both bands.

For the next year, and for residential systems much longer, I think 802.11g systems will enjoy significant popularity because they are less expensive (for the moment), and you don't have to worry about the kinds of issues that institutions and public access providers do. While home users typically have sub-megabit WAN connections, 802.11g could be worth the 10%-20% price premium to many folks because it is good for sharing files and local multi-media transfers (maybe even from a set-top box.)

Well, that's my $0.02 for the day.

Stay Resonant,

Dr. P

Dr. Protocol is a shadowy figure who uses his powers to make networks safe for children and small, fluffy animals. He also consorts with the upper echelons of various technical cabals including the IETF, the OIF, and the 2600 Society. When he's not working undercover assignments or foiling plans for world domination, he works with his handler, Frank Hujber, at their consulting firm Perihelion Associates (www.perihelionassociates.com). Dr. Protocol is all guts and glory, but finds time for a few hobbies, including pottery, paintball, hand-spinning his own optical fiber, and interplanetary solar wind surfing.

Your questions for the Doctor are welcomed, and may be sent to: frank@perihelionassociates.com

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