Breaking Wi-Fi Gridlock

 
 
By Guy Kewney  |  Posted 2003-09-10 Email Print this article Print
 
 
 
 
 
 
 

Wi-Fi traffic jams will keep growing, writes Wireless Center Editor Guy Kewney. Is a "congestion charge" the best solution?

Cynicism is underrated in the technology business. Any fool can look at a new tool and imagine the utopia it will usher in. It takes a rather special type of cynic to look at the phone and predict the engaged tone, the irritating ring tone, the "network congested" sign and the phone-theft gang. Even so with Wi-Fi wireless. This week, I notice, Sharp is announcing its "first wireless TV"—something of an odd sobriquet, given that broadcast TV is as old as the hills. Its really a 15-inch LCD display with the ability to stream video over a Wi-Fi network.
Or you can look at PC Magazines review of RoomLink—a system for distributing video around a home either over Ethernet cable or over high-speed 802.11a WiFi at 2.5GHz.
And if thats not enough, theres more wireless enthusiasm from Linksys with its Wi-Fi Webcam. When you see these things, you wonder if people read the news. Wireless snafus at TechEd in Barcelona and CeBIT in Hanover have been well-documented. Both incidents had the same simple cause: An expert network installer failed to produce a working network because there were too many wireless units. Speech is a wonderful thing, too; but when we invented speech, as a species, there were no cocktail parties. Go into a room with 100 people in it, and you cant hear yourself think. You certainly cant hear what anybody else is trying to say, which is probably why young people resort to embraces and dancing in situations of high background noise (and probably why they arrange the high background noise in the first place!).
The same applies to situations where there are too many Wi-Fi devices in one space. Im not suggesting that this is a question that can be solved simply by using more channels. Channel overlap is a known problem with Wi-Fi. There are only 11 Wi-Fi channels in the USA (13 in Europe) but in either case, there are probably only three usable channel bands. If you use a channel right next to someone else, then you get interference; everybody knows that. What Im talking about is simple background noise. In a room with two Wi-Fi clients, each gets around 5 Mbits of bandwidth of its own (2.5 Mbits of "payload," as the experts will quickly tellyou). Take it up to 20 clients, and you have to cut that down to 250 Kbits of data per second. Still OK, mostly. But put 3,000 clients into a big hall, or in a city square, or a shopping mall—easily done!—and the amount of sheer wireless noise reaches the level that you cant actually punch a signal through. In Hanover, at CeBIT, people recorded network speeds of 9,600 bits per second. You wouldnt use a fax that slow. In Barcelona, one of the worlds most competent Wi-Fi engineers, marshaling the combined resources of Microsoft, HP and Proxim, spent five days struggling to find out why throughput was down to 40K most of the time and completely dead the rest of the time—and failed. If youre going to start pumping video over Wi-Fi, then youre going to chew up huge amounts of bandwidth. If you start providing universal Wi-Fi with Wi-Fi phones, PDAs, banjos and sponge-buckets all talking to cars, gas pumps and TV tuners, then youre going to clutter the airwaves. In some large cities, you now have to pay to drive your own vehicle. In London, for example, the surcharge is five pounds per day. Thats because anybody can use the road—and so everybody did until it became unusable. Wireless, license-free, is in the stage of the small boy walking in front of a Model T Ford waving a red flag. Traffic jams are unimaginable ... or are they, really? What is almost certainly going to have to happen is a congestion charge. Well have to evolve social mores to say who will provide the access point for an area, and what rights the rest of us have. Well have agreements about turning off clients that arent being used. Well have a shift from private wireless transport to public infrastructures. Or does someone have a magic answer? Guy Kewney is among Europes best-known IT writers, having covered the PC and communications businesses since the mid-1970s in print, on TV and radio, and latterly on the Web. He has regular columns for Personal Computer World, IT Week, and The Register, and is editor of www.NewsWireless.Net—and has more portable and mobile bits and pieces than anybody could carry, including his own portable Wi-Fi access point and three different cellular data cards. His objective is to be omnipresent on the Internet.
 
 
 
 
 
 
 
 
 
 
 

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