Wireless Routers for Congested Areas?

An anonymous reader asks: "I have been living close to campus at UW Madison for the past six months or so and have come across a problem. We, along with everyone else in the area, have a wireless router, both a Belkin 54g and a Linksys WRT54G. We have Charter 3 Mbit down/.25 Mbit up cable and 6 guys in our apartment. Just on our block about 15-20 people have routers. We are constantly plagued with problems connecting to the wireless, staying connected, getting connected after rebooting, hibernating, and so forth. We have to reset the cable modem and the router many times a day to get everything rolling again. I am thinking that the router is the problem, because my dad always told me that's why they have twenty dollar routers up to thirty thousand dollar routers. What router can I purchase that will help my situation and will work well in a congested college area?"

Comments

Anything that runs dd-wrt

[lavid]

You can boost the signal strength on routers once they're flashed with DDWRT. Do that (up to like 80mW) and use the least used channel and you should be good.

Re:Anything that runs dd-wrt

[LoRdTAW]

To better understand the grandparent with respect to antenna gain and maximum power dissipation, here is a little analogy:

The maximum power for the 2.4GHz 802.11x is 100mW. Antennas are usually compared to a reference point which usually is a 1/4 wave dipole antenna. So think of it in terms of compact fluorescent and incandescent light bulbs. A 100 watt Incandescent give you a mix of light and heat which is very inefficient (1/4 wave dipole). A compact florescent can give you 400 watts worth of light with the same amount of power the 100 watt incandescent uses (high gain antenna). so a 100W incandescent would nicely illuminate your own driveway but a C.F. lamp would flood the area with light annoying your neighbors while consuming the same amount of power. The power consumption is the same between the two lamps but their ability to radiate that power into light varies greatly. Same applies to antenna design.

Now the reason crappy low gain dipole antennas are used is this, you want to keep interference down so you use a crappy antenna that has little chance of picking up your neighbor's wireless router or microwave. BUT the transceiver has enough transmission power (100mW) to get a decent signal out of that crappy antenna to your clients and vice versa. A 100mW transceiver with a high gain omni directional would not only open your network up to interference from other 2.4GHz devices but you would flood a wider radius with your RF power interfering with other wireless systems. So its legal to get the power to 100mW but only with the crappy dipole. If you used a 3dBi omni @ 100mW it would be comparible to pumping 200mW into the dipole which is illegal. So while it sounds enticing to use high gain antennas on both the clients and AP, its going to cause only more headaches for your network and the networks that surround you.

Hopefully I have explained this properly as its been a while since RF/communications class.

Re:Anything that runs dd-wrt

[greg1104]

The peak output setting available for the WRT54GL I have when running dd-wrt is 250mw. As you say, it would be unwise to push to the limit. Similar to the GP post here, I'm running mine at 75mW. It works dramatically better than the default 28mW. The last time I came across a good analysis from someone with test equipment, for that particular model the distortion level made the effective useful maximum around 100mW of output.

Re:Anything that runs dd-wrt

[Anonymous Coward]

In the US it is legal to use a high gain antenna, but illegal to use an amp. I.e. legal to use that 3dbi gain antenna on a 100mw radio for a ERP of 200mw. NOT legal to use a 2.4ghz amp to boost that 100mw into the OEM antenna, even if both methods resulted in exactly the same range.

Re:Anything that runs dd-wrt

[poopdeville]

There's no such thing as a "high gain omni-directional antenna". An antenna's gain is defined to be the logarithm of the ratio of signal strength and what an omnidirectional antenna's signal strength would be. (To be precise, the definition involves "perfect" omnidirectional antennas. The so-called 'isotropic' antennae)

Obviously, the ratio of what an omni puts out and what an omni "would" put out is 1/1. The gain is therefore 0 dBi.

Your lightbulb analogy is the perfect example of this idea. A plain old lightbulb will put out 100J every second, but "split up" evenly in all directions. A 100W spotlight will put out the same power, but illuminate the spot much more brightly. It is a "high gain" light. The plain old light bulb is a "no gain" light, because gain is defined in terms of what it outputs. Indeed, high gain antennas are inherently more directional. Just a minor detail.

This is a good point for me to respond to the Ask Slashdotter. You already have two fairly capable routers. I know the Linksys will easily run OpenWRT, HyperWRT-thibor, etc. HyperWRT allows (*ahem*, I forget exactly what they call it) wireless "bridging", which lets you run multiple routers as access points to the same wireless network. (So instead of having two separate WLANs, you have a "roaming" cell phone-like effect). HyperWRT also gives you some control over how much power the router's transmitter can use.

Depending on your home's architecture, you might want to look into using high gain directional antennae. You want to use directional antennae to help eliminate RF leakage. If your neighbors can see your wireless network, you're radiating power that could be useful to you. In this case, your router is also picking up your neighbor's noise.

So figure out where you actually use your wireless network. Use high gain antennae to "illuminate" those spots. Look into "cardioid" or "log directional" antennas. Also, check out http://en.wikipedia.org/wiki/Log-periodic_antenna. It has a nice picture of the energy distribution of a log directional antenna over North America. Obviously, you're working on a smaller scale, but the idea remains the same. Put the antenna in a corner, radiating towards the longest dimension in your home.

I suspect that a firmware upgrade and some smart antenna placement will solve your problem.

2 Routers?

[bobbozzo]

Why are you running 2 routers? Isn't that just compounding the problem?

Use Kismet or NetStumbler, and find a channel with no strong signals nearby, and use that one.

Try different antenna orientatations.
Put a metal reflector behind the AP if it's in a corner of the house.

Asus

[micksam7]

I've been using a D-Link 524 router for a while in my home setup. It's given me nothing but trouble, rebooting and randomly blocking computers on the network [part of it's built-in security junk, it's blocking logs show it will block perfectly valid computers for random reasons]. Firmware updates don't seem to fix it.

I got tired of that and searched for a router capable of running OpenWRT in case the default firmware sucked.

I found the Asus WL-500g Premium and bought that for about $100 at the time. The default firmware worked fine, but I decided to try openWRT, then tossed that in favor of X-Wrt which had a better web interface.

The router's current uptime is 37 days with no crashes or any oddities what so ever. Last restart was for a firmware reflash.

As for reception, try lesser-used channels. 6 is a really common channel, so try 1 or 11 instead [or any other channel].

Note however, that if you go the path of openWRT or X-wrt, you're going to have to spend some time working out the kinks at first. Mine worked fine, except wifi couldn't access wan, which took a bit to figure out how to fix it; openWRT's wiki and forum were a big help in figuring out that.

Re:Asus

[volsung]

Just to note: On the 2.4 GHz band used by 802.11b and g (and n which can do both 2.4 and 5 GHz), there is substantial frequency overlap between channels. Channels 1, 6, and 11 considered "non-overlapping" (which is mostly true, though not entirely). Channels 1 and 2, however, interfere quite a bit.

This is another advantage to the 5 GHz band used by 802.11a and 802.11n. The 5 GHz band is divided into channels which do not overlap, which allows a lot more concurrent access points to be run. Unfortunately, 5 GHz does not penetrate through walls as well, which limits the area you can cover with one access point. But in a high density housing area, you likely don't have very much area to cover, unless you are trying to split your wifi with your neighbors. :)

Change your firmware on the Linksys...

[Fallen Kell]

Check what version of the WRT54G that you have. You should be able to run "DD-WRT" on it. This read up on doing the flash properly as you can nuke your router if you put the wrong image on first. Basically there is a "first time flash" image to use. And then once you have put that on it, you can flash to the full version that your router supports. Again, it will depend on which hardware version of the WRT54G you have as there are something like 6 different revisions, some more powerful then others and some more friendly for using third-party images (due to having more storage on the device, some have as little as 2MB total space for the OS, others can have as much as 16 or even 32MB of space).

Now, once you have flashed it, you can use additional channel space that is normally unavailable to use as it is reserved bandwidth. I forget which channel ID it is, channel 14 I think is not normally accessible in the USA. Change to that channel and most of your interference should go away from other competing devices.

Now, other things to do, turn off the broadcast SSID. Setup the MAC Address Filter and only include the MAC addresses of devices that you want to allow to connect. You can now even setup your own local DNS and statically assigned DHCP addresses for devices (in other words, your device still does the normal DHCP request, but you always get the a specified address for that device, useful if you have any kind of file sharing or network server).

Other things you can do is boost your antenna gain in the software if you have poor coverage in the house/apartment. You can also try specifying a specific antenna to transmit or receive, which can be useful if you want to upgrade an antenna with one of your own design, or something you purchased. I personally have a 16 dbi omni on my wireless router. I also have a 24 dbi directional in case I ever need to do something like making a wireless bridge. Using something like that could potentially let you connect to your campus's wireless net and use their higher speed pipe that your student fees already pay for.

Re:Change your firmware on the Linksys...

[ComputerSlicer23]

Now, once you have flashed it, you can use additional channel space that is normally unavailable to use as it is reserved bandwidth. I forget which channel ID it is, channel 14 I think is not normally accessible in the USA. Change to that channel and most of your interference should go away from other competing devices.

Nice to see someone recommend you break the FCC rules (which I believe puts you in violation of a Federal Law)... *Sigh*. The FCC for all it's problem does actually do the frequency splits for a real honest to god good reason. Everything above 11 is outside the USA frequency range, you use 14, because that puts you the furthest away (which leaves you less overlap with 11, each channel overlaps with the next 4 or 5 channels). As to what is usable where, see this page from Cisco. What the parent is recommended is an FCC violation, probably punishable by a fine. Not sure if it's punishable by jail time. In general, what you'd like to do is actually work with the people in the area to work out a workable system. While this local optimization might work for you, if everyone does it, it's a problem. Along with the fact that it will cause problems for whoever actually is using the licensed equipment in that frequency range. First figure out if you have crappy equipment, or figure out if you have the wireless spectrum in your area is just flooded. If it is, work as a with the folks you live near to mitigate this. They are flooding your network, you are flooding theirs. Set up one network, setup multiple networks and coordinate channel usage. Get everyone to tone down their power settings (thus the signal won't go through walls). As several others have suggested, use directional antennas. Use a different technology to for single room access and use wired for long haul.

Kirby

Any DD-WRT router

[WhiteWolf666]

Simple. Get any router than you can install DD-WRT from http://www.dd-wrt.com/ on.

Everything is tweakable, the system is very stable, even in high traffic areas, and you will be able to get it to work reliably (mine does, with 15-20 other access points visible). In fact, I have two, and one serves as a wireless bridge, in a very high traffic area. I've had 40 days or so of up-time.

Even better, you get things like forced QoS, a lot of flexibility in terms of services (DyDNS? Check. Local DyDNS? Check. Excellent Port Triggering? Check. An iptables based firewall? Check. 802.11 briding? Check), and a future-proof, at least in terms of encryption, router (WEP WPA WPA2).

Re:Any DD-WRT router

[WhiteWolf666]

Hmmm...

I suspect you might have to tweak your settings. I get an incredible amount of mileage out of these things :-)

We've got 4 running at my office, one as a main router/DHCP server/QoS firewall, one as a primary access point, two as bridges. The main one does QoS, and we've got ~8 employees online at any given time, with a non-trivial amount of network traffic, especially when I'm here.

We also run all of our phone over vonage (6 lines!), all through this little DD-WRT box, and it runs like a champ. Load averages about 1, which is a little high, but it keeps on running just fine. I find that it helps to keep the "router" box running without wireless enabled, with a secondary box to handle wireless functionality.

Why do I prefer DD-WRT to a separate computer, like I used to have? Simple; reboots are faster, the hardware is drop-dead easy to replace if there's a failure, and power consumption is substantially less.

*shrug* Works for me, but I get that YMMV.

Re:N?

[CliffSpradlin]

This is very bad information. Current 802.11n draft devices use 2.4 GHz, same as b and g. The only devices out on the market that use 5 GHz are 802.11a.

Also, 802.11n draft devices have a knack for fucking up non-n routers in the vicinity..you may be screwing the people around you over.

Re:N?

[micksam7]

Actually the 802.11n spec CAN use the 5GHz range. Says Wikipedia

You just have to hope your router actually allows it. :)

Have you thought using 802.11a

[Oryn]

There are many old 802.11a access points available on ebay for very little money.
The Proxim ones can be flashed with a web interface rather than the telnet based one they arrive with.
I have one here and it works great, once setup just plug into your router and go.
Of course you will need an 802.11a capable card for your laptop. I was able to find a minipci intel dual band one for about $20.

Good points:
802.11a has more channels than b/g
802.11a less range and is more effected by walls etc meaning less interference
Its 5.2Ghz so your 5.8Ghz phone is not going to interfere
Reasonablely inexpencive

Bad points:
The Proxim I got doesn't support wpa-psk so only with a radius server can you use wpa
You need a 802.11a radio to use it, although dual band radios are getting to be more common, they are still not that common.
The signal doesn't go as far, you'll need more access points to cover an area.

Sommoderators will moderate anything up, it seems.

[Inoshiro]

Because of how "channels" work (how they map to the actual frequencies), the only usable channels (that is, channels far enough away to not suffer interference) are 1, 6, 11.

7 8 9 -- all of those will suffer from the same problems from people on channel 6. 802.11[bg] is not designed to work well and play with others.

A few tips from a tech support guy...

[mikael_j]

I run into problems like this on a daily basis and there are lots of different things you can try to get your signal strength up, some won't be very useful on their own in your situation but every little bit helps.

Some of these tips are a bit "brute force" for those times when you can't coordinate your setups with your neighbours' setups, others require cooperation to work well..

• First of all you could try finding out what channels your closest neighbours are running their networks on, and then try to find a channel that's as far as possible from those channels.
• Next you could try moving your wireless access point and/or your computer
• It might also be worth a try to change your encryption settings, switch to WPA-PSK or WPA2-PSK if you're using WEP or the other way around, sounds crazy but sometimes it actually helps, kind of a cargo cult solution but it's worth a shot.
• Directional antennas on both your AP and your NIC might help but it's probably easier to just use regular ethernet over CAT5E/6 if your computer is a regular desktop/tower machine.
• If you are able to talk to your neighbours and coordinate your efforts with theirs then you could try setting up the different WLANs in the building so that everyone turns their signal strength down a bit while also changing channels in such a way that no two adjacent networks are running on channels that are adjacent to each other, the closer two nets are geographically the further away from each others' channels they should be.
• You might also want to make sure that you don't have any other electronic equipment that's causing problems, I've seen cordless phones that weren't even supposed to be running on the 2.4GHz band cause problems with WLANs and TVs...

There are a few other tricks you could try in order to boost signal strength but a lot of those really only apply if your signal strength is bad without there being other networks nearby, like if your access point is far from the computer then you might try getting yourself a repeater but I'm guessing you're in a fairly small apartment so that shouldn't apply..

/Mikael

Re:Sommoderators will moderate anything up, it see

[BeBoxer]

7 8 9 -- all of those will suffer from the same problems from people on channel 6. 802.11[bg] is not designed to work well and play with others.

Actually, you will see worse problems. 802.11 is in fact designed to work well with overlapping networks. Devices on overlapping networks will watch all the packets in the air on the same channel, including those on other networks. They will backoff when they see other devices sending packets. You can still get bad congestion of course, but the devices are at least trying to play nice.

If you switch to a neighboring channel, like 5 or 7, then the devices can't play nice any more. Instead of being able to hear and understand the traffic on other networks, it all just shows up as big blasts of noise. I actually did a bunch of testing of this years ago. If I put two AP's on channel 1 right next to each other and ran simultaneous transfers with two clients, the aggregate bandwidth was about 95% what I would get with two clients on 1 AP. But when I moved one AP to channel 2, it dropped to 75%-85%. At channels 1 and 3, it dropped into the 70%--75% range. After that, it climbed, getting back to just over 100% at channels 1 and 5. Channels 1-6 got me up to 180% of the original throughput and 1-7 up to 210% of the original. In retrospect, I had the AP's way too close which explains why I still saw interference at the 1-6 step. But assuming your neighbors aren't putting their access point 2 feet away from your own, this shouldn't be an issue.

So what's my point in all this? Stick to 1, 6 and 11 for everybodies sake. I have actually heard of some sites using four channels with, I guess, three channels of separation. So 1,4,7,10 for example. I haven't testing this and I'm not convinced it's really any better. Because the performance at three channels is about the same or a little worse than the same channel. It only starts to get better at four channels of separation, but then you have to use 1,5,9,13 and channels 12 and 13 aren't permitted by the FCC.

Simple Solution

[Pikoro]

This is easy. Pick up a Japanese wireless router. They come with channels 12, 13, and 14. Get yourself off of everyone else's frequencies and you'll be good to go.

Alternatively, you could set up a small linux box with a wireless card and set it up as an AP on channel 13. Assuming you are using a linux desktop, you should be able to take any buffalo card and drop it onto channel 13 with no problems.

For a windows box... install the japanese drivers and you will be fine.

Almost all buffalo products have japanese equiv. models. Grab the japanese firmware and re-flash your firmware...

Re:N?

[spacey]

You've got your product buzzwords backwards.

  Power over ethernet provides DC over pins that are not used for data on an rj-45 connection. What you're talking about is powerline ethernet (or ethernet over power).

-Peter

Easy - Use a wired connection.

[pla]

Wireless has its uses. I will not deny that.

But I can't count the number of people who have asked me for help with their home networks, who have a cable/DSL modem, a WiFi router (often built into the modem these days), and a single PC - All sitting on the same desk (or at least within the same smallish area such as one wall of a room).

And to elaborate on the FP's example, I dealt with a situation two days ago where a friend kept having trouble with his WAP (one client and one laptop connected to it). Turns out he didn't even connect to his own AP! The laptop could see something like 15 APs, half of which had just "linksys" as the name, and only one used WEP. And on the flip side of that, he had about a dozen people randomly using his AP, over time. Really makes you feel confident in the RIAA's John Doe SLAPP suits based on IP address, eh?


The real "problem" here comes from the perception that we all need wireless (a perception not helped by the fact that most broadband providers try to convince their users to buy crappy low-end modem/WAP combos). Well, we don't! Personally, I run a 4-7 machine LAN at home, and have it totally wired for both security and reliability reasons. And for the rare occasions when I want to use my laptop outside, I do actually have a WAP, which I only turn on about four time a year.

Simple heuristic for everyone - Regardless of the number of machines on your home network, do they move? If not - Run a damned wire! Even if you mostly use a laptop while sitting on the couch, it actually takes less time to plug a 6' cable into a nearby wall than it does to connect to a WAP (though the latter you usually don't notice because it just looks like yet another part of the obscenely long Windows boot process).