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What's better? More WiFi networks or fewer?
August 2, 2014 10:25 AM   Subscribe

Devices share bandwidth on a network. WiFi networks compete for bandwidth with each other. Is it better from a user/performance perspective to have multiple networks and spread the devices out among them, or a single network with all devices using it?

I'm mostly just curious, I realize the differences would likely be too small to notice during general use.

We upgraded our Internet service yesterday and it included a new combo cable modem/dual-band WiFi router. The tech also plugged our existing dual-band WiFi router into it, so now we have 4 networks we can connect to (one 2.4GHz and one 5GHz per router).

We have some devices that can use 5GHz and others that are limited to 2.4GHz. But on a given band, would it be better to connect various devices to different networks so they don't compete with each other as much on a network, or to unplug the second router so the routers don't compete as much for bandwidth/channel space?

We live in a building where there are about 15 networks visible when scanning for wireless if that makes a difference.

I know that the data all comes through the same pipe* ultimately so this isn't a question about the total volume of data we can stream at a given moment. I'm just curious about whether more networks or fewer is clearly preferred given a the same number of devices connecting.

*It's pipes, right? Or does the Internet still come through tubes?
posted by under_petticoat_rule to Computers & Internet (6 answers total) 7 users marked this as a favorite
 
In general, as you acknowledge at the end, the wireless node isn't the limiting factor in total throughput on any single device. So there's really not going to be a performance benefit from distributing your devices onto different nodes. I would definitely pitch all but one, if only for the simplicity of having fewer routers to manage.

There's also a tragedy of the commons thing going on here. There are only 14 specified wireless channels, and when multiple base stations are using the same channel in the same vicinity it degrades the quality for both parties. Given that you already see 15 networks around you, having FOUR of them be your devices is basically making everyone else's life a little worse when you're transmitting on those channels. It's possible to run base stations in a mode where they all use the same channel and the same SSID but that's typically just a signal strength / coverage play. If you're in an apartment building it almost certainly isn't worth the work.
posted by heresiarch at 11:22 AM on August 2 [1 favorite]


As heresiarch indicates, it's all about what channels the various networks are on. You can use a tool like NetStumbler or iStumbler to see a list of the access points in your area and what channels they're using.

The question is interference. Let's say that you have two dual-band access points, and there are no other neighbors or access points for miles. If you configure the four radios (two 2.4Ghz, two 5Ghz) to each use a different channel, and none of those channels overlap, you will indeed have maximized the amount of bandwidth you have available. However, if you configure the two access points to use the same channels as each other, and they're both broadcasting in the same bands, they will have to share - there is likely to be no benefit to having the second access point, and in fact, overall performance will be slightly diminished due to the number of transmissions the additional access point would be doing just to advertise itself.

In your apartment, you would want to first make sure that your two access points aren't using the same channels, since that's a total waste. Next, you will want to make sure that none of the channels they are using overlap with any of your neighbors' access points (using the tools I linked to above). Finally, you may well want to turn off one of the access points, just to avoid wasting bandwidth (and being nice to your neighbors).

That said, different access points provide different levels of performance based on the antenna design, the chipset, the firmware and other factors. It's entirely possible your old dual-band router provides better performance, either throughout or range, than the new one they provided. If I were you, I would set each of the radios to non-overlapping channels, then run speed tests on all of them, to see what works best in your environment - and then I'd turn off the two least performant radios.
posted by eschatfische at 11:48 AM on August 2


Note that there are only really 3 (4 if you live in some areas) wireless channels that don't interfere with each other. Only channels 1, 6 and 11 can transmit without interfering with each other.
posted by pharm at 12:02 PM on August 2 [2 favorites]


My company actually uses multiple WAPs with the same SSID and same passphrase (or other authentication) to strengthen signal/speed for end users, mostly because our network engineers seem to believe that a WAP can only handle a certain number of attached devices. I believe they interleave the channels, but I'm not entirely sure.

But we're talking about hundreds or thousands of attached devices, not a couple dozen.
posted by kalessin at 12:06 PM on August 2


I actually do this for a specific reason - I have a couple of the older Airport Express routers that I use for Airtunes. The way the older ones work is each time you add one to a network, the capacity is cut in half. So having three, my speed is 1/8 of what it should be. I keep them on their own network/band and have my other devices connect to the faster N network.
posted by bradbane at 12:44 PM on August 2


It's worth making sure as many devices are using the 5Ghz as possible.

While 2.4Ghz only has 3 non-overlapping 20Mz channels (1,6,11) 5Ghz has up to 22*, depending upon device support and some will not be available if used by reserved services near you. Once you factor in neighbourhood routers, the 2.4Ghz will get even more congested, as 5Ghz support is still mostly only used by more expensive stuff. In addition, plenty of other things use 2.4Ghz, such as baby monitors, cordless phones, and microwave ovens (they usually operate at 2.45Ghz, but leak a bit, which is why 2.4Ghz was made available for unlicenced use in the first place) which leads to yet more interference.

The downside of 5Ghz is range; it penetrates walls and floors less; which is great for blocking neighbourhood 5Ghz routers, but also means your own router will penetrate less far.

Given local interference, range, walls, and device chipset variations, sometimes you're better off with one router, sometimes you're better off with a router and a wireless access point some distance apart.

Given the range issues with 5Ghz, you're probably better off using two, several rooms apart to give coverage, on different channels - distance to the router is likely to be a bigger factor than anything else for final throughput (and of course, run wired networking to the second router, and use it only as a wireless access point, not a full router, and turn off DHCP on it).

For 2.4Ghz, it's pretty much situation dependent, and you'd have to test throughput at various places with both 2.4Ghz radios active in different rooms (on different non-overlapping channels), or only one active and see which option gives you the best tradeoff between range and interference across your property. Use different SSIDs for all when testing; use the same SSID for automatic device switchover when deployed.

Putting them side-by-side is a waste of time though with 802.11n or better - the limiting factor will not be the router capacity. If that is your only option, test each in isolation to see which is the better one - transmit power, chipset performance vary etc - and go with that as your sole device.


* To get the higher speeds with 5Ghz, it uses channel bonding; on 802.11ac, you can get up to 80Mhz connections, or about 3 or 4 non-overlapping. There's also MIMO, which uses multiple antennas to get more throughput using the same amount of radio bandwidth via phase control.
posted by ArkhanJG at 2:12 AM on August 3


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