Mesh May Save the Wireless Bands

 
 
By Guy Kewney  |  Posted 2004-11-22 Print this article Print
 
 
 
 
 
 
 

Opinion: You thought spyware slowed you down? Try Wi-Fi congestion. But with mesh networking, you can win the battle for bandwidth.

The first thing you suspect when your PC starts crawling is a virus or spyware. Not radio congestion. Ive been running spyware blockers. Its congestion, however, that is going to be the nemesis of wireless networking. And the problem may strike first in Europes jammed urban districts before it hits the more spaced out North American suburbs. There are two ways to solve this problem—with social engineering or with the use of more spectrum. Its going to be fascinating to see which will be adopted first.
The problem is that the standard Wi-Fi network has only three non-overlapping channels. If four access points using 802.11b or 802.11g are set up, two of them will be on the same channel, and reception suffers. Is this a problem? Well, where I live in London, it is starting to become one.
Click here to read how Broadcom is extending Wi-Fi range even further. I dont live in a particularly difficult neighborhood; its not next to an office tower block. The houses are only three stories high, and people arent all technology buffs. But each house is divided into two or three apartments. Each apartment has broadband. And now the apartment owners are switching to wireless. Do the math. It gets scary. Roughly, the situation is that my immediate neighbors on either side can just pick up the signal from my network. Thats four households. But the wireless access point will also reach five houses on the street opposite and two or three houses on the street behind. Thats because it doesnt really matter what the house is built of—timber, stone, brick or concrete—if the signal can go through the windows. So multiplying those eight houses by the average two apartments per building, you can see that this gives me a potential of 20 wireless LAN nodes in range, and perhaps more if everybody goes wireless. What that would be like doesnt bear thinking about. Right now, we dont have that situation: The market is still young, and we have only seven WLANs in range. Fortunately, it would seem that four of them dont know about changing channels from the default of Channel 6. One does, and has switched to Channel 11, so I switched to Channel 1. The result was magical. The Internet had been like treacle. My wife found that she was connecting, then disconnecting, three or four times a minute in bad stretches. When things were good, she could stay online for an hour at most. But even my own PC, right next to the access point in my den, was losing connections some times. And the main symptom, even worse than the intermittent connectivity, was that downloads were slow—often down to 10K bps. As I indicated earlier, my suspicions (and the best guess of most of my expert friends) were that wed been infected by some sort of malware. We chased it, found a few, removed them, and it didnt improve. And it was then I thought to run NetStumbler and do a site survey of the neighborhood. So my first strategy is to switch to 802.11a. Strictly speaking, this isnt entirely legal. The UK is ahead of some European countries in allowing 5.8GHz WLANs for some purposes, but without transmit power control (TPC), its not kosher. Then again, nobody is going to come down the street with a detector van. Even if it were a requirement that made a significant difference, TPC and the other requirements of 802.11h, which is the European version of 802.11a, arent high on the radar of the regulators. Indeed, they have to be prodded to take action against pirate radio stations that are blocking licensed wireless users over an area of several square miles, never mind private users with a range of a few meters on unlicensed channels. Next page: The problem with 802.11a.



 
 
 
 
 
 
 
 
 
 
 

Submit a Comment

Loading Comments...
 
Manage your Newsletters: Login   Register My Newsletters























 
 
 
 
 
 
 
 
 
 
 
Rocket Fuel