Cutting Through a Wi-Fi Traffic Jam?

eric3xxx asks: "A week or so after Christmas, I tried to connect to my home wireless network and while I could see my access point I could not connect. After scanning the network, it turned out that there were at least twenty new access points in my apartment building (and in the surrounding buildings). Most of them had names such as 'linksys' and were all set on their respective vendors default channel (apparently a lot of people received 802.11b/g WAPs as presents). I tried changing the channel on my access point, starting at 1 and continuing through all of the channels, and none of them worked (probably since the channels overlap). In any case, I have no clear solution to this problem. I suppose I could boost the signal, however, that also increases noise. Perhaps I could convince my neighbors to put together a shared wireless network. I may just switch to 802.11a since it isn't as widely used." Has anyone else had success in configuring their APs to work in an areas of heavy wireless traffic?

Comments

Change Your Firmare?

[OctaneZ]

If your router supports it, grab an open source firmware, and step outside the normal 1-11 channels. Channels 12 - 14 are almost guaranteed to be empty.

Re:Change Your Firmare?

[Jeff DeMaagd]

step outside the normal 1-11 channels. Channels 12 - 14 are almost guaranteed to be empty.

It doesn't work that way. Each channel is spaced 5MHz from the last, but WiFi uses 30MHz bandwidth. Someone using using channel 11 is still overlapping more than half of your needed bandwidth, even if you use channel 14.

Re:Change Your Firmare?

[olibri]

Also, American antennas are tuned for channels 1-11. You will lose a LOT of power and range if you try to use 12-14. I believe that 12-14 is only for Japan, and last I heard, they don't use it either.

Re:Change Your Firmare?

[epiphani]

Note, this is technically illegal in the US. You're broadcasting outside the legal FCC range. Channels 12-14 are generally used for european users.

Not that this should stop you. Those handy firmwares also let you bump down (or up!) your broadcast strength. I recomend bumping it down to as low as you can while still getting the distance you require. I run my WRT54g at a comfy 12.5% of the possible output.

Re:You poor guy.

[JeffSh]

the default password on linksys wireless routers is "admin" im sure it will work still :)

Re:here, it's not so much the WAPs...

[NNKK]

The FCC didn't assign 802.11b/g or cordless phones to 2.4GHz, it's an unlicensed band that anyone can do whatever they want in within certain limits on power and such.

802.11a will get loved to death, too

[puzzled]

The 802.11b/g spectrum is being loved to death in your building. If you've got twenty devices trying to share only three non overlapping channels (1,6,11) its a mess if anyone wants to go fast.

Setting the channel is the first step but you'll still get adjacent channel interference. Setting SSID *DOES* *NOT* *HELP*, nor does WEP/WPA. SSIDs define a group of nodes that are going to associate but the media layer (OSI layer 2) is *shared* for 802.11. That means two properly secured networks on different channels are still sharing the same stream of NAV (network allocation vectors) and they'll be stepping all over each other.

I could go on about this but I've got the flu and you've got internet access - get Matthew S. Gast's fine O'Reilly book on 802.11 and learn all the gory details for youself.

Put the power where it belongs!

[jonbrewer]

Locate your AP at the outside corner of your flat. Attach a pair of reflectors to the antennas, such that radiation will be concentrated only on your flat.

By directing the power over 90 deg instead of 360, what do you think you have just done? Not only have you increased the transmit power, you've also vastly increased the receive gain.

Reflector templates can be found here:

http://www.freeantennas.com/projects/template/inde x.html

I was in a situation where I needed broadband in an apartment w/out a connection, and used a DWL AP2000+ in client mode with one of these antennas (styrafoam, a kitchen knife, aluminum foil, and cellotape) to pull a symmetric 3.5mbps from an AP 600 meters down the street.

Make sure to put the reflectors on both antennas and point them both in the same direction. In almost all cases with such APs, only one antenna is transmit, while both receive.

Re:Craptastic

[OctaneZ]

Wow, that was unnecessarily offsensive post, you are right, it needs a better home page.

Here is what is included:

Wireless:
. Power Transmit Ajusting (12.75dBm ~19mW -> max 19.25dBm ~ 84mW)
. TX & RW Antenna Selection ( Left Diversity Right)
. Support for 14 Channels (WorldWide)
+ Will support for Bridge and Repeter, WDS mode in final release

System & Network:

. Support for subnet 255.255.0.0 & 255.0.0.0
. Static DHCP
. DNS Local
. SNMPD ( Works right with mrtg)
. Support VPN Passthrough (IPSec - PPTP - L2TP )
. Add 'Server Profiles' for easy configure up to 14 Host Servers
( FTP,HTTP,HTTPS,DNS,SMTP,POP3,Telnet,IPSec,PPTP,Ter minal,VNC,Emule,Ident,MSN)
. Up to 14 Port Range Forward settings
. VPN Server (PPTP) Buld-in
. Support for Zone-Edit, Custom Dyndns DDNS
. Telnet Shell
. Remote Wake On Lan support
. Easy Reboot and Restart all service just a click
. Ping & Traceroute hacked for allow run shell command
. AutoRun Bash Script - Easy set an autorun script each time router reboot
. Status with more infos like Uptime & CPU Load, Wireless Client List
+ SSH Shell
+ Bandwidth Management
+ VPN Server IPSec
+ VPN Client (PPTP & IPSec)

** . = Current release | + = Will be add in next release **

Updates:
iptables 1.2.9
PoPToP v1.1.3
pppd 2.4.2
busybox 1.0 pre7
pptp 1.4
net-snmp 5.1
Kernel 2.4.20 Tweaked

Re:Lemme get this straight...

[rcw-home]

There is a relationship between the size of the holes and the wavelengths that seep through so if you know which wavelengths you want to keep out, you can tailor your cage to match your requirements.

For those following along at home, you can use Google Calculator to help you with this.

1/10th wavelength is a generally accepted mesh size for blocking RF. You can be more paranoid if you want (for example the holes in your microwave oven door are about 1/50th wavelength).

To calculate 1/10th of a wavelength at 2.45GHz, type "c/2.45GHz/10" into Google. Bam, 1.22 centimeters. Anything conductive with holes no larger than that will function as a faraday cage for RF up to that frequency (and will probably significantly attenuate RF in higher frequencies as well).

Re:You poor guy.

[Qzukk]

The answer is no.

When you establish a connection, one IP address is used for the source of that connection, and after that, thats the path the traffic runs.

If you had two cable modems doing 5Mbps, you could download 2 things at 5Mbps (one using each modem) but you could not directly download 1 thing at 10Mbps (if its http or ftp, you could cheat and use the "resume" feature to have one cable modem download the first half while the second downloaded the second have, and then your specially written client would assemble these together.)

Channel bonding can be done with the appropriate hardware and ISP, but I'm willing to bet that your cable provider is both unwilling and incapable of setting this up. (With bonding, only one IP address is used, and the hardware passes traffic down whichever wire is free/not broken.)

what's missing here, is this...

[CFD339]

First of all, Have you considered that the issue could already be the walls themselves? You have not described your apartment, but many apartments have foil backed insulation or even chickenwire backed adobe or plaster in the walls.

Second, you're probably getting as much overlap from portable phones as you are from AP's in the building.

My advice differs from so many others. I say, centrally locate your AP in the apartment at the same plane as you'll generally be holding your laptop. That usually means about 30 inches for tabletop, about 20" if its actually on your lap keeping your genetals warm (and isn't that really why we all want Pentium 4 HT processors?).

If you're still not connecting on any channel, you probably have a config issue. Start with the basics. Reset the unit to factory config and change only the password. let it broadcast its SSID. Connect, then starting tightening it down. Don't sweat the hackers until you have something of value. Clearly, they don't need your bandwidth.

Also, learn about what blocks this frequency. In a nutshell, water. Anything with water. PEOPLE, for example, are excellent at blocking wifi. Your walls may have plaster that was water based. Chip off a piece and put it in the microwave for a few seconds. If it heats up, it will block wifi. The same goes for PVC plastics. Most won't, some will. A chip in the microwave for a few seconds will tell you.

I can't tell you how many times I see people in a coffee shop with wifi connection problems, when they've set the 900 ounce mochofrappafuckamacallit right next to their wifi card. DOH! If the signal is iffy, that's more than enough to kill it off.

Finally -- make sure you hit the basics. Get the latest (actually, sometimes teh second to latest) drives for teh wifi card and the AP, as well as any firmware upgrades. Don't laugh, sometimes it's really not plugged in.

You're in an apartment. Run some damn wires. Snake them under the carpet or hang the from the ceiling. Put lights on them and make them festive. Let your geek flag fly.

Re:Get an old microwave

[Boronx]

It's a time honored American tradition to shoot your neighbor's wayward animals, although in this case if you just wing the cat a couple of times it will probably get the message.