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At work, we have two wireless networks (e.g., Work1 Work2); the Work2 is used downstairs and Work1 is used upstairs. However, both are notoriously slow. The connection is better when we are wired in, but unfortunately due to our building being very old and our company growing very fast, most employees are not seated near the walls where the ethernet cables are.

I had Cox, our ISP, run a bandwidth utilization test and it doesn't seem like we are capping out on upstream/downstream, which leads me to believe that it's strictly an issue with the wireless networks (which were implemented before I got there).

The wireless networks are both Apple Airport Extremes. Is there anything I can do to improve the situation for everyone?

Speeds are extremely slow, and sometimes drops out.

john
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    Does your building have a suspended ceiling ? You could drop a cable run down inside a tube form the ceiling and run the cables to clusters of desks into the middle areas of the room. It's quicker (as a temporary solution than raising the floor and putting floor ports in) – Sirex Jun 13 '13 at 01:32
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    You want multiple dual-band access points, wired to each other. Preferably cheap, reliable, and that can run OpenWRT, Tomato, or DD-WRT. E3000's used to be the best choice but they're no longer widely available. – David Schwartz Jun 13 '13 at 01:40
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    @DavidSchwartz Are OpenWRT, etc. based devices really the right choice for building a medium/large size network? While they're better than basic consumer firmware if you're putting a bunch of them together in a single network wouldn't something more enterprise oriented with a central admin feature (vs having to log into each one separately to configure it) be a better choice? – Dan Is Fiddling By Firelight Jun 13 '13 at 12:48

4 Answers4

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I'm going to put this as gently as I can: Wireless networks (802.11) suck.

The 2.4GHz band (802.11b, g, and some n devices) is a festering pit of radio noise.
Everything from baby monitors to microwave ovens pollute this section of the spectrum, and the wanton proliferation of wireless networks has it so congested that you're frankly lucky to get 1Mbit speeds out of it in some urban areas (in the building my company is in the 2.4GHz band is unusable - average throughput is less than 100Kb/sec).

The 5GHz band (802.11a, some n, and the new ac draft standard) is better in terms of interference, but you wind up taking a penalty in overall range (because 5GHz signals get eaten up more readily by the little things people like to have in their buildings, like walls).

In both cases you're using a shared medium (wireless frequency) -- this means everyone else's signal is effectively your noise: the more people using the wireless link the worse this gets as devices are fighting a limited slice of frequency spectrum and time.

Wireless "range extenders" just make the problem WORSE -- the extender is now chewing up radio spectrum to relay traffic back to the base station (adding more traffic and congestion to the airwaves).

For more detail than you probably ever wanted to know about wireless networking, check out the blog posts the Server Fault team did when they were fitting out their office wireless network:

So what can/should you do?

Ideally you should run cables to the high traffic locations, and leave wireless for things that are truly mobile (laptops going to the conference room, cordless VoIP phones, a "guest network", and stuff like that).
Like Sirex suggested there are other ways to go about running cable that don't require a major remodel (but please check your local building codes before you start throwing wires through your ceiling).

The ideal solution may not be practical, so the next best thing is to build a wireless network with multiple access points that use a wired backhaul to get to your main network.
Apple documents how to do this with the Airport Extreme on their site, and you can find similar guidance from other manufacturers.

Some other things to bear in mind:

  • One WAP can support about 15-25 users (depending on how heavily they use the network).
    If you load WAPs/coverage areas above this number your performance will suffer.
  • Your WAPs should have minimal coverage area overlap if possible
    Remember the signal from one set of devices (WAP+Clients) is just "noise" to the other sets.

Cisco has some basic guidelines on setting up a wireless network which make for good reading.
They also have more advanced documentation, but my Google-Fu is failing me at the moment.

Community
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voretaq7
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    I have to echo your sentiment: Wireless networks (802.11) *do* suck. In almost every appreciable way they are inferior to wired networks. –  Jun 13 '13 at 02:20
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    The wireless technology is not the only barrier here. The OP has not stated how many people use it wireless also do they transfer files about the office? If you have many devices it might simply be a case of maxing out the bandwidth available on the wireless. – Peter Jun 13 '13 at 02:27
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    Our warehouse had a wireless network. We had this odd gain effect through the rollup doors facing the street that made the network a very efficient failing ignition system detector. During certain times of the day various old junkers from the local highschool would cause interesting dropouts in the traffic. Nothing beats CAT6 Gigabit ethernet cable. 802.suck is relegated to mobile station use only traffic now. Interference and internal bandwidth saturation are death to wireless speed. – Fiasco Labs Jun 13 '13 at 06:22
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    Another thing that wasn't mentioned is that only one client can be trasmitting at a time on a single wireless network. If two clients try to transmit at a time, they both stop, wait a random amount of time, and try to send again. This is the same thing that happens using a hub for wired clients; so, even if your wireless signal is absolutely **perfect**, you are still essentially connecting all everyone using a hub, which is **awful** with even 2 or 3 clients doing anything other than web browsing. – BlueRaja Jun 13 '13 at 15:16
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    @BlueRaja IIRC 802.11ac allows a router with multiple spacial streams to either combine them all to give a single client a faster connection (like in previous versions), or to connect each stream to a separate client allowing several to be transmitting concurrently. – Dan Is Fiddling By Firelight Jun 13 '13 at 15:42
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    @BlueRaja What you're saying is true for 802.11a/b/g/n and single radio APs, but Dan is correct: in 802.11ac "Multi-User MIMO" was added to the specification. (This is basically taking the "multiple antennas, multiple streams" stuff 802.11n introduced and doing the next logical thing: If your AP has 8 antennas and you have 4 clients with 2 antennas each client can use two streams and they can all talk simultaneously -- at least *in theory*. We'll see how it works in practice as 802.11ac deployments start popping up.) – voretaq7 Jun 13 '13 at 15:46
  • @Dan and voretaq: True; I assumed OP isn't using 802.11ac yet.. – BlueRaja Jun 13 '13 at 16:30
  • @voretaq7 good point about how often wifi practice falls well short of theory. – Dan Is Fiddling By Firelight Jun 13 '13 at 17:06
  • Devices from companies like Ubiquiti in their Unifi range are 'friend-device aware' and automatically tune power (ie range) to prevent overlap with other APs. Also allows very easy SSID extending, by doing it over the cable, but allowing you to use one SSID across all APs. Great devices. – Ashley Jun 18 '13 at 21:53
  • The other important thing to pay attention to here is how much your channels overlap. Make sure you're not shooting yourself in the foot by using channels 1 and 2 or otherwise adjacent channels. You ideally want your APs running on channels, 1, 6, and 11 only in the 2.4 Ghz spectrum. If you for some reason can't use two of those, make sure to put them on the same channel (ie, both on channel 1), which is better than adjacent channels due to the way they communicate and interfere with each other in each case. – Nick Jun 20 '13 at 13:45
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Whilst i agree with voretaq7's general sentiment, many devices don't give you a choice about whether to run wireless, and there are a few things you can do on the wireless side:

Firstly, iperf/jperf is a toolkit to test your bandwidth and see which areas are suffering. Run the iperf listener on a system with a good quality Gigabit wired connection, and run jperf on a test laptop - preferably one that matches the most common model your staff use, since chipsets and antenna setups have a lot to do with how well things work. Do several runs of the client in each location to be sure you are getting a consistent result.

Next is to determine what interference is actually present. There are lots of expensive solutions for this, but one that has worked remarkably well for me is Wifi Analyzer, a free Android app that allows you to see wifi signals in various different ways. (Make sure you do it on a device that supports 5 GHz - my Samsung Galaxy S2 does, and most newer equipment should support it these days.) This won't let you see non-802.11 interference from things such as microwave ovens or Bluetooth, but it's a good start, and very low-cost. (A similar tool on Windows is Xirrus' Wifi Inspector.)

In my experience, most urban areas have huge clutter in the 2.4 GHz band where there are only 3 non-overlapping channels (1, 6, and 11), and almost nothing in the 5 GHz band where all the channels are non-overlapping (23 of them in .au - your region may have more or less).

Use the channel graph view in Wifi Analyzer; if you can see more than one signal above -75 dBm or so in the non-overlapping 2.4 GHz channels, or if there are devices in any other channels (e.g. my neighbours have a pocket wifi device that has chosen channel 3), then chances are that your devices are fighting interference. Do the check for both 2.4 GHz and 5 GHz, and put your AP in the channels which have the least competition.

Lastly, even in a congested band, you can improve things by using an AP that works around interference. To my knowledge, Ruckus ZoneFlex APs are the only ones which can do this on a per-client basis in real time. (I'm unaffiliated with Ruckus - just a relatively happy customer.) Get a couple of ZF7982 or similar dual-band units, do dedicated cabling runs to each one, configure different SSIDs for 5 GHz and 2.4 GHz, and get your clients to use the 5 GHz SSID by default so that they're using the less-congested spectrum.

These APs are not cheap, but they constantly amaze me at how well they work in a congested spectrum, and if they're improving your staff productivity, they'll pay for themselves in a matter of days. If your boss is "buy something now, ask questions later" type, you could probably do this as the first step and have an immediate win, then tune things more once it's in place.

Paul Gear
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I would first take a look at different locations with InSSIDer or Wifi Analyzer/Android and check the channel levels at different places in the building/floors, check the that the wifi channels used are free and not too busy. Try and space the different Apple access points on different WIFI channels, manually. Also check that you do not use in between/overlapping channels as that will cause interference and bad Wifi performance.

Check that the wifi channels are placed like the article suggest. http://windowsitpro.com/mobile/wi-fi-best-practices

If that still does not help I would get professional access points from Ubiquity UniFi 2.4Ghz,5GHz or Aruba Networks. The advantage with Ubiquity is that the controller software is included run on a standard PC and does not require a huge investment in controller hardware, but you do get a tool to manage the access points.

Christian
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While I certainly agree that wireless networks in general are a troublesome area if you want them done right (tm), I do not agree that wireless in itself is FUBAR. What needs to be done basically depends on what your problem looks like:

If your problem indeed is noise, you should be looking at a band with less noise. Use a spectrum analyzer to check the frequencies in question over a period of time to find vacancies in the spectrum.

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Take a look at your current AP's stats data to get an idea about your current data throughput. If your problem is concurrency of the data sent through the access points (you have the transmission channel saturated for extended periods of time), you should be looking at access points with segmented directional switched antenna arrays. Enterprise-grade APs for any 802.11 standard (including the old 802.11b/g) with this feature are in the market for a while now.

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And, of course, if you happen to have high access point density, centralized automatic transmit power management and channel hopping for access point radios (as implemented in WLAN controllers) does help tremendously as well.

If your problem is with many stations transmitting data at once, you might want to use stations with beamforming capabilities for transmissions (basically 802.11ac or stuff advertised as MIMO for the time being).

enter image description here

the-wabbit
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