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« FCC Throws a Spitball | Main | Bigger Fish »

May 12, 2002

Will Success Spoil Wi-Fi?

Apparently, some people think so. In the last few days, I have read several articles, all of which quote DeWayne Hendricks. Two of these articles are noted in yesterday's post on FCC rulemaking. Hendricks appears to be everywhere, and while not opposed to 802.11b or other unlicensed specifications, is raising the fear of the Tragedy of the Commons to heights I haven't seen echoed elsewhere. [Pushback on this piece has already come in: see below.]

The Tragedy of Commons is stated succinctly thusly: shared resources, when they become popular, are unusable for their original purpose. In the ur-case, we're talking shared pastures. The shared pasture protocol was that common inputs resulted in a common resource. When the common use of the resource exceeded the resources ability to replenish, the commons is destroyed. Or, to loosely quote Yogi Berra on Coney Island, it's so busy nobody goes there any more.

I don't want to put words into Hendricks mouth, and I don't impute motives to other people. Hendricks is a big wireless proponent, and his consulting firm helps companies working in new and interesting areas, including ultrawideband (UWB), which could be spread-spectrum's successor for data transmission.

However, I hope we can get more clarity from him about some of the many public statements he has made lately, which I believe may be focusing too closely on one aspect of Wi-Fi specifically, and all unlicensed low-power data specs in general.

For instance, this morning, David Weinberger's excellently thought-provoking Journal of the Hyperlinked Organization (JOHO) points to David Isen's Smart Letter #68 which reprinted an article of Isen's from March. (Whew.)

Isen notes the following: Hendricks is concerned that as 802.11b gets popular, its very popularity will make it harder to use. The 2.5GHz band [sic: should be 2.4 or 2.45 GHz band] could become so crowded that nobody will want to go there. Densely spaced 802.11b transmitters will make it more difficult for receivers to distinguish desired signals from undesired ones. Hendricks fears that people will respond by trying to amplify (or otherwise boost) the 802.11b signal. Indeed, such hardware hacks already abound. ... Virtually every 802.11b hardware hack is illegal, he says. And this is only part of the destruction-by-popularity story. Other devices – like portable phones, Bluetooth devices, and (soon to come) radio-driven lighting – operate in the same 2.5GHz [sic] frequency band.

Isen continues: Hendricks thinks that 802.11b is a train-wreck in the making. Furthermore, he says, there is nothing to prevent 802.11a (also unlicensed, operating at 5+ GHz) from following a similar trajectory. As currently conceived, unlicensed spectrum could devolve into a hobbyist's playground.

The contentions here are individually not unreasonable, but collectively appear to point to a subset of all wireless use which shouldn't affect the vast majority of users or locations.

The vast majority of Wi-Fi usage, and the vast majority of future 802.11a usage, will be indoors: in homes and offices, schools, and public venues like airports. Most of these indoor locations will, by their very nature, limit incoming signals from interferring transmitters unless those transmitters are so ridiculously boosted that the FCC simply steps in, issues fines, and shuts them down.

In the typical installation, there are no interferring transmitters, as the real-estate owner, lessee, or renter has no near neighbors or has a construction that prevents exterior signals from leaking in at levels that interfere with usage. In some small percentage of installations, adjacent consumers or businesses are operating similar systems. A combination of antennas, system design, and cooperation on channel usage can solve those problems in most cases.

In the very small percentage of Wi-Fi which is taking place entirely in the common, such as the overlap of hot spots across parts of San Jose or Palo Alto between the several for-fee providers that offer service there, cooperation would be the name of the game. No one user would drown out the others in the same space as that would prevent any effective use of the technology. Any user pursuing that tactic could be shut down or fined by the FCC, depending on their particular apparatus.

Really, the issue that appears to be in the forefront of Hendricks's mind -- and I'm not a mind reader -- as well as Steve Stroh (Focus on Broadband Wireless Internet Access newsletter) is the widespread development of illegal hacks to Wi-Fi equipment. These hacks are not illegal to discuss, unlike some of the copyright issues arising from the DMCA. Rather, they're illegal to deploy. The FCC may approve an access point, but they don't approve Pringles can antennas to work with them. There are some fine points to all this, including the right to make non-commercial antennas that appears to be part of the Part 15 rules.

But Hendricks and Stroh are correct: many informal installations violate Part 15 rules, and as these installations increase, the likelihood of rendering some part of the public space in dense urban areas unusable increases.

What none of the articles addressing this appear to note, however, is the subtext of the Yogi Berra bon mot: a beach may still be "usable" (that is, enjoyable) to some people if it's packed body to body, but spectrum is not. If interfering transmitters reduce the utility of a given public space network, the network would be shut down. It might be shut down by force (FCC fines), by agreement (if you can connect to a network, you know who runs it, ostensibly), or by apathy (hey, it doesn't work any more).

There's no cause to increase the density of network deployments when you can't use the ones that are already there. This seems like common sense: networks don't appear by magic, they have to be set up by people who need the utility of employing them to a purpose.

Another technical point to make is that Hendricks sounds like -- and again, I don't believe this would be the case in context -- he doesn't know about channelization available in 802.11b, g, and a; nor about the co-existence work happening in Bluetooth and HomeRF alongside IEEE efforts.

Wi-Fi has 11 legal channels in the US and more or less elsewhere. Three of those channels don't overlap, allowing dense network deployments at full speed in adjacent regions. However, many adjacent channels would still work even with interference at lower speeds. Because of the built-in step-down options in various wireless networking specs, a lack of usable clear signal at 11 Mbps doesn't necessarily mean you can't talk at 2 Mbps. For outdoor, public space deployment in which the uplink to the Internet is likely 256K to 1 Mbps, this isn't a problem, either.

802.11a has the chance to further reduce interference by offering eight nonoverlapping channels in the 5.150 to 5.350 GHz range and another four higher up the spectrum in 5.725 to 5.825, specifically reserved for certain outdoor applications, such as point-to-point.

Of course, if you have 50 transmitters in the space of a few hundred square yards, all the channels in the world don't help. But an increasing interest in commercial infrastructure building by fewer partners appears to be part of the evolving public-space market.

Commercial wireless network companies don't use illegal gear; if any are, their investors will string them up by their thumbs when the FCC comes calling, as it certainly would. (Their competitors would turn them in, if no one else did.)

But beyond that simple obvious point, commercial infrastructure for wireless is clearly moving away from multiple overlapping networks in the same public spaces to rentable hot spots. Concourse is a harbinger of this direction, having been chosen for the Minneapolis/St. Paul airport in part because they offer a network-neutral approach. They built the infrastructure; iPass is handling access. From my discussions with both companies and other firms in the industry, the only issue is how much iPass wants and on what basis for access to the network. But Boingo, Wayport, T-Mobile, and anyone else can tie in for a fee. And that's increasingly likely to happen.

One more point in this whole debate: HomeRF and Bluetooth won't wind up eating Wi-Fi's lunch. HomeRF, if it continues to grow as it has, is a pure consumer spec, and it employs frequency hopping. Adjacent users of Wi-Fi and HomeRF might see some minor degradation, but many companies selling HomeRF gear now also sell Wi-Fi. You can't imagine them not working towards a co-existence solution more formally to avoid these very problems.

Bluetooth has already solved co-existence, and Bluetooth 2.0 will incorporate the solution embodied in the IEEE 802.15.2 task group. Although a number of Bluetooth 1.1 devices are out there, in a few years, there will be a vastly larger number of 2.0 devices as that spec starts appearing.

Likewise, the 802.11h task group built an adaptive set of responses into 802.11a that will surely find their way into the 2.4 GHz band as well: use only as much power as you need, and don't treat on in-use frequencies.

Taken together, the current developments and future solutions in the works paint a picture of ever-more co-existent technologies and companies, and a more managed informal use of the space. I'm not a libertarian by any definition, but it looks to my eye as if the market (comprising commercial vendors, community networks, and home users) may solve all the problems of the common.

I'm optimistic: people may crowd the beach, but they're not masochists. Would you put your umbrella and blanket down if you knew that every minute a volleyball would land in your picnic basket and someone would run right over you pursing an errant child? Probably not. The beach that's so busy people don't go there has worked out an informal system of usage that preserves its common function. The cost: privacy and solitude. The benefit: society and common use.


Steve Stroh thinks the above is factually inaccurate, but he hasn't elaborated. He's an industry veteran and has great insight, so hopefully he will push back harder on this to present an alternate view that incorporates what he thinks the real facts are.

Dave Sifry of Sputnik blogged about the FCC's role.

Robert Scoble wonders based on his recent conference experience what happens when you have a lot of competing Wi-Fi networks in one space? This is where mesh networks could be handy: with a mesh protocol, each addition sub-network helps strengthen the network by co-opting and cooperating, adding a node, even if it's got private attributes, instead of overlapping bandwidth.

On the co-existence front, let me reiterate: very few manufacturers will wind up with single wireless investments. They will make Bluetooth and HomeRF, Bluetooth and Wi-Fi (several firms already), Wi-Fi and HomeRF (Proxim, for instance). They have vested interests in promoting co-existence, not spectrum competition.

5/13: I exchanged email with DeWayne Hendricks today with a plan to talk more about the context of how he's been quoted on these issues. As I suspected, he's got a much bigger fish to fry than he's been quoted about. More later today.