802.11(g): Jumping the Gun

April 1, 2003
There have been recent reports that 802.11(g) wireless LAN (WLAN) systems dont interoperate flawlessly with some 802.11(b) clients. Surprise! Of course,

There have been recent reports that 802.11(g) wireless LAN (WLAN) systems don’t interoperate flawlessly with some 802.11(b) clients.


Of course, anyone who has followed the development of 802.11-compliant systems wasn’t really surprised. It was mostly the mainstream media journalists looking for the next hot-technology-issue-about-which-we-can-express-concern-and-consternation who have appeared to be surprised by this "news."

Why? Let’s examine the clues that would lead to this non-surprise.

But first, we should understand the issue and where 802.11(g) fits in the IEEE 802.11 standards alphabet soup.

The major issue is the fact that, in some instances, the 802.11(g) system's throughput drops off markedly when an 802.11(b) client enters the network. In other words, the entire system defaults to the slower 802.11(b) device's data transfer rate.

802.11(g) can be seen as an extension of 802.11(b) — the first of the high-speed wireless LAN standards. 802.11(b) offers speeds up to 11 megabits per second (Mbit/sec). 802.11(g) promises speeds up to 54 Mbit/sec.

Wow! (Except that the usual disclaimers apply: "your mileage may vary," "data transfer rates in the lab appear faster than those in the real world," and so forth.)

Incidentally, there's also 802.11(a) which already offers up to 54 Mbit/sec data transfer rates but operates in the 5 GHz band. Despite the fact that 5 GHz systems offer a number of advantages over 2.4 GHz systems, 802.11(a) hasn't seen the same level of implementation as 802.11(b). While 802.11(a) is somewhat more expensive than 802.11(b), it's just as likely the reason is that 802.11(b) was available first (and was therefore implemented) and 802.11(a) systems aren’t compatible with existing radios and access points.

That's perhaps the key point in why 802.11(g) has been developed — and why there are reported interoperability problems. 802.11(g) is supposed to provide the speed of 802.11(a) yet be compatible with 802.11(b) radios (although only at the client’s slower speeds).

You can quibble about the relative merits of 5.4 GHz versus 2.4 GHz systems all you want. But that's another topic entirely.

Back to why we shouldn't be surprised that the first 802.11(g)-compliant systems don’t interoperate flawlessly.

Clue #1: The 802.11(g) standard isn't a standard yet. It's still in draft form, not expected to be finalized until the middle of the year.

Clue #2: Vendors haven't agreed on how to interpret the standard once it is approved. While most of the technical issues have been resolved, anyone who remembers the implementation of 802.11(b) will remember that there's a lot of room for interpretation in standards. And that means different implementations. It will take some time to sort everything out.

Clue #3: There have been news releases about vendors being "first to ship draft 802.11(g)-compliant" devices. As with most technical advances, being first to market is seen as a major competitive advantage (as perhaps was the case with the 802.11(b) versus 802.11(a) systems). So some manufacturers are willing to gamble on the final draft in order to be first to market. (Incidentally, this also makes final approval of any standard much more entertaining as vendors with conflicting pre-approval implementations try to make a case for their interpretation.)

Clue #4: 802.11 equipment has never interoperated flawlessly right out of the gate. That's why the Wi-Fi testing facility at the University of New Hampshire was established. Companies submit their equipment to UNH for testing to uncover incompatibilities with other manufacturers' devices. During the initial Wi-Fi testing program, some of the first 802.11(b)-compliant devices couldn't even recognize that there was another 802.11(b) device present. So the fact that some 802.11(g) systems only slow down when they encounter an 802.11(b) client is pretty good news.

Clue #5: The interoperatility problems were uncovered (and reported) by the Wi-Fi testing facility at the UNH. So, might we guess we’re not quite ready for prime time here?

So, who jumped the gun on 802.11(g)?

Admittedly, some vendors are, shall we say, a bit ahead of their safety nets at this point. But more, it's the mainstream media that have leaped to conclusions about 802.11(g).

Most of you weren't surprised by this "news." You, like me, would have been totally flabbergasted if everything had worked flawlessly the first time. After all, we live in the real world. [email protected]