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IT Shops Coping With Overloaded 2.4GHz WiFi Band 165

Posted by Soulskill
from the crowding-the-ethertubes dept.
alphadogg writes "Of the 470,000 Wi-Fi connections made on a recent day at Abilene Christian University, fully 94% used the 2.4GHz band, representing an extreme example of how today's surging number of Wi-Fi clients is crowding the band least able to accommodate them. At ACU, this is not considered a problem, at least not yet. In part, that's because of careful wireless LAN design and capacity planning. And partly because a goodly percentage of mobile devices that can run on the alternative 5GHz band, do so: on that same day, 47% of the school's laptops and desktops, and two-thirds of its iPads cruised on 5GHz, via either 802.11a or 802.11n. Yet relatively few of today's Wi-Fi clients support 5GHz."
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IT Shops Coping With Overloaded 2.4GHz WiFi Band

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  • fully 94% used the 2.4GHz band

    100% of 94% ? Or 94% used the band fully?

  • WTF?? (Score:2, Insightful)

    by Anonymous Coward
    94% used the 2.4GHz band


    47% ... cruised on 5GHz,
    • Doesn't 802.11n use both?
    • by Anonymous Coward
      94% of everything on 2.4GHz. 47% of laptops and desktops on 5 Ghz. 66% of iPads on 5 GHz. 100% reader failure.
    • Re: (Score:3, Informative)

      by Lev13than (581686)

      At least RTFS - 94% of all connections used 2.4GHz, while 47% of iPads used 5GHz. Most devices are either G only or 2.4GHz N. People generally avoid 802.11a and dual-band 802.11n often isn't turned on. So those numbers are not surprising.

    • by loufoque (1400831)

      94% of the 2.4Ghz bandwidth was used, not 94% of the people were using 2.4Ghz.

      • by Obfuscant (592200)

        94% of the 2.4Ghz bandwidth was used, not 94% of the people were using 2.4Ghz.

        No, of the 470,000 connections, 94% of them were made using 2.4GHz. Not "94% of the bandwidth was used". "Fully" is an adjective adding stress to how high the number 94% is.

        They then switch units from "connections" to "systems" and report that 47% of the laptops and desktops used 5GHz. Also 2/3 of the iPads.

        I suspect that laptops and certainly desktops account for very few "connections", since the connection is made once and held open. There are also a very large number of smart devices that connect an

  • At least on my home network. Much slower and shorter range.
    • The shorter range means that you won't have as many other access points conflicting with yours.

      The only problem I've seen with 5GHz is that fewer end-user devices are supporting it.

      • by Alamais (4180)
        Yeah, I'm a little annoyed that my Nook doesn't support 5 GHz. It's basically the only reason I still keep a 2.4 GHz network running at home.
        • by Tanktalus (794810)

          I had to completely disable the n support on my 2.4GHz band just to get my ASUS android table to connect. Which I thought was nuts. To be fair, I haven't tried again since upgrading from Android 3.0 to 3.1 and then 3.2.

          I left the 5GHz band on (obviously n) for my laptop to use. Not much in the way of interference that way, but for the likelihood of collision, it's somewhat of a waste.

      • by skids (119237)

        The only problem I've seen with 5GHz is that fewer end-user devices are supporting it.

        ...even the ones that have 5GHz radios -- they will choose a 2.5 signal over a 5 even if they can get full speed over the 5, even if the 5 offers dual band 11n and the 2.5 does not. They will ride that crowded band into the ground when there is a perfectly usable 5 band right there for the using. The drivers don't seem to be able to distinguish correctly between a crowded band with a string signal and an uncrowded band with a weaker, but still fully capable signal.

        So tip to geeks -- if you want speed, tur

        • by hawguy (1600213)

          So tip to geeks -- if you want speed, turn off your 2.5G radios when you are in range of a 5G AP. Even in cases where you can't get a 54Mbps signal, as long as you aren't down in the 1-4mbps range, you'll be one of like three people using the band so it will be faster for you.

          I split my SSID's across frequencies - I advertise one 802.11b/g SSID at 2.4Ghz and a different 802.11a SSID at 5Ghz, so I connect to the 5Ghz SSID with devices that can take advantage of it, and let the devices that can only handle 2.4Ghz use the other SSID. I regularly experience network drops at 2.4Ghz, but no problems at at all on 5Ghz. I can see about 30 - 40 AP's on 2.4Ghz from my apartment.

          About the only thing I use Wireless for is to connect to the internet, so 802.11a works fine for me, I don't nee

  • I attend a state funded technical college in Kentucky. We just had a technology audit/overhaul done over the summer break. Before summer, I could always connect to the wireless without a hitch. Sure it was a little slow, but it worked. After we cane back from the summer, I can't even get my wifi to associate with the router. Turns out, they redid the subnet ting and only allow 255 ip addresses to be leased at a time. 255 ip addresses. On a school network. Where everyone has a laptop and a smartphone. What t
    • Parent here. Sorry for the typos and lack of structure. iPhone's don't make for friendly slashdot commenting companions.
      • Parent here. Sorry for the typos and lack of structure. iPhone's don't make for friendly slashdot commenting companions.

        It's not your fault. And for once it's not even Steve's fault.
        Slashdot doesn't make for friendly Slashdot commenting.

    • by Anonymous Coward

      I attend a state funded technical college in Kentucky. We just had a technology audit/overhaul done over the summer break. Before summer, I could always connect to the wireless without a hitch. Sure it was a little slow, but it worked. After we cane back from the summer, I can't even get my wifi to associate with the router. Turns out, they redid the subnet ting and only allow 255 ip addresses to be leased at a time. 255 ip addresses. On a school network. Where everyone has a laptop and a smartphone. What the hell? I talked to the it guys and they said they're waiting to hear from the ISP so the can raise the number of leased up addresses. That doesn't make a whole lot of sense. Someone explain that one to me?

      If they need to talk to their ISP to up the leased address space, that would seem to imply they are using public space vs private space. That is just stupid and irresponsible. If they are using public space, they generally can only get issued a class C at a time if they have a large network requirement. What they should be using is the 10.0.0.0 space and NAT at the edge..

    • WTF were they thinking? They could use a class A or B for more IPs or go so far as to use VLSM if they want a classless headache.
    • by skids (119237)

      Either they have a small global address allocation to start with (and are trying to disable NAT), in which case they have to get more from the ISP or apply for more as an institution, or they decided to "outsource" their WiFi so that it is run as a turnkey system by an ISP, and that ISP did not allocate enough addresses for the need.

      I could also see them wanting to segment WiFi if they for some reason decided not to turn off broadcast forwarding entirely (the saner thing to do if you have no mission-releva

      • There isn't enough info for us to know for sure. Assuming the parent poster is living in dorms. The deal with the ISP probably has the AP's VLAN'ing the SSID's back to their controller, and the university is probably just allowing the ISP to run their cabling on the uni's property. This is becoming a common setup for cash strapped organizations like colleges and hospitals since it cuts down on net admin costs. Well...in the short term anyway.

    • by NevarMore (248971)
  • It's one of the ubiquitous technologies which always seems to have something crippling it. Interference, noise, hardware compatibility, exploits, proprietary protocols. The 2.4Ghz problems will evolve the same way on the 5Ghz band. The only reason it's not a problem now is the reason stated in the article. Not that many devices are in the 5Ghz band.

    • by skids (119237) on Monday October 24, 2011 @03:32PM (#37822368) Homepage

      The 2.4Ghz problems will evolve the same way on the 5Ghz band

      Not really. 2.4G has 3 bands. 5G has, depending on the country has 4 to 8 times as many. Make that 2 to 4 when you turn on dual channel bonding, and then you are talking worst case 6 channels. That means that you can tesslate the 5G band much closer together, without APs that are on the same channel getting as close to each other (and no, dropping Tx power isn't a perfect solution to that problem on the 2.5G band.)

      So it's much easier to microcell on the 5G frequencies, in fact AP density can be cranked up absurdly high.

  • I find it largely annoying that "Wireless N" doesn't imply support for 5GHz. Many "Wireless N" devices only support 2.4GHz and most are bad at labeling whether they support 5GHz or not. It makes it difficult if you're looking for devices that support 5GHz "Wireless N".

    From a cost perspective, I understand why they might only support 2.4GHz. I just wish they called it something else, like "Wireless NS" or something.

    • "NS" for 2.4 GHz-only would just be confusing. It'd look like "N5", which one might assume means 5 GHz.
      • by drinkypoo (153816)

        What would have not been confusing would have been to just not call anything that will only do 2.4 "N". But noooo....

    • by Alamais (4180)
      Never happen. Who wants to label their device as lacking a feature?
    • by msauve (701917)
      "most are bad at labeling whether they support 5GHz or not."

      In my experience, it's the "not" that's the problem. If a device supports 5 GHz, it will almost always say so (usually labeled "dual band"), because it's a marketable feature. If they don't support that band, they say nothing.
      • by Mia'cova (691309)

        But even then, some require manual configuration to pick a band, others can switch on-the-fly, and others can use both 2.4 and 5 at the same time. So even among devices which do support 5 GHz, there's a range of support.

    • by skids (119237)

      ...which is why you look for products labeled "abgn" since you'd probably be hard pressed to find a product that supported both a and n but didn't support n on the 5G radio.

    • 802.11a (Score:4, Insightful)

      by xororand (860319) on Monday October 24, 2011 @04:11PM (#37823050)

      Look for 802.11a support. It requires the 5 GHz band.

      • by fostware (551290)

        Oh for a +1

        802.11a (or 802.11abgn) *is* something that will be on the outside of a box, giving some certainty.

        Except the cheap-ass Broadcom chips Samsung use top out at 72mbps . Yeah, it supports N, but it's only to tick a box.

  • by chill (34294) on Monday October 24, 2011 @03:09PM (#37821992) Journal

    Look at the number of smartphones, e-readers, laptops and Android tablets out there that don't support 5 GHz. With the premium price of some of these gadgets I'm surprised vendors are trying to shave expenses by getting 2.4 GHz-only 802.11n chipsets.

    If you get an opportunity, let the vendor or salesman know you one of the features you look for is 5 GHz capability. Make a point of it.

    • by Alamais (4180)
      I know, I've been pondering a tablet, but it's hard to tell what even supports 5 GHz. Do any of the current 10"-class tablets?
      • by chill (34294)

        Motorola Xoom is the only one, I believe.

      • I know, I've been pondering a tablet, but it's hard to tell what even supports 5 GHz. Do any of the current 10"-class tablets?

        The iPad does. My wife's iPad can connect to either our 802.11b/g 2.4GHz network or our 802.11n 5GHz network.

        I'd like to kill off the 2.4GHz network, but we've got too many devices that still need it - including my new-ish Android phone.

        • Just curious - assuming you've got an Apple wifi - Does the dual-band Airport Extreme Base station, which has 2.4GHz and 5.8GHz chipsets, alleviate the 2.4GHz blues?

          • Just curious - assuming you've got an Apple wifi - Does the dual-band Airport Extreme Base station, which has 2.4GHz and 5.8GHz chipsets, alleviate the 2.4GHz blues?

            My 802.11n Airport Extreme was the earlier, single-band version - so I've got that handling 5GHz and an older Extreme (the one that looks like a white Hershey's kiss) taking care of 2.4GHz. But I can't imagine a dual-band Extreme wouldn't still be subject to the fundamental limitations of the 2.4GHz band.

      • I was fairly impressed when the touchpad detected my 5GHz network. Great buy for $99, will be even better when they port ICS to it.

      • by tlhIngan (30335)

        I know, I've been pondering a tablet, but it's hard to tell what even supports 5 GHz. Do any of the current 10"-class tablets?

        Easy. Look for 802.11a support.

        All good tablets will have one of two labels for the WiFi - 802.11bgn, or 802.11abgn. (If the tablet doesn't have 802.11n support, back away from it and pick another one).

        802.11a only works on 5GHz. If you don't see it on the list, then it's 2.4GHz only (including N). If you see a, then it's 2.4 GHz (b/g/n) and 5GHz(a/n).

        Smartphones I can understand not

    • by JamesP (688957)

      Then on the next couple of years we get congestion at the 5GHz band

      It's not about band, it's about intelligently using the resources. Unfortunately, 802.11g is very bad at this, 802.11n is better, still, I think there's a long way to go still...

      • by chill (34294)

        Congestion at the 5 GHz band will be harder to accomplish. The 2.4 GHz band has only 3 non-overlapping channels for use in the United States. The 5 GHz band has 21 non-overlapping, 20 MHz-wide channels.

        The 2.4 GHz band also has to deal with Bluetooth and Zigbee traffic, in addition to additional background noise created by microwave ovens and fluorescent lights.

        Finally, signal transmit distance in the 5 GHz band is shorter than 2.4 GHz. This means in low-to-moderate density areas there won't be as much over

    • by adolf (21054)

      I've had an Intel 802.11a/b/g wireless card in my laptop for well over half a decade, and have never encountered an access point in the 5GHz band that I want to use when out and about. Nobody, in my not-so-limited experience, operates a public 5GHz hotspot.

      To be clear: I do use the various 5GHz ISM bands for all kinds of long-range communication in my day job, and really appreciate the available spectrum and general lack of interference as compared with the near-universal mess that exists at 2.4GHz.

      But as

      • by chill (34294)

        Out and about? I agree. At the office or home, however, I prefer the 5 GHz band so as to not contend with all the clueless noobs and their cable box/wifi hotspot crushing the 2.4 GHz spectrum.

        • by adolf (21054)

          I live in a big house which, while definitely in-town by any measure, sits on a fair bit of land. There are something like 16 access points shown on my Droid while standing in my driveway...but four of them are mine. (I've currently got two access points that I actually use, just because I can. The PS3 also becomes an access point when it's turned off for Remote Play(tm). And I use AT&T's provided access point only to broadcast obscure and sometimes dirty SSID beacons, again just because I can...)

          Of

  • There are only around 5.000 students at ACU based on their website. Even if their 5000 faculty and employees you are averaging 47 logins per person.
    Does half the town of Abilene use the university as a hot spot or what. Even with an average of two devices per person that seems like a lot of users.
    of course you could always throttle which ever band gets say more than 70% of the traffic.

    • by Pharmboy (216950)

      Keep in mind that Abilene has 117k residents of all ages (2010 census). That sounds like a whole lot of connections for my former home town. Plus they are on the NE side of town, not near most of the shopping or traffic, which is on the south side, so incidental traffic can't the be cause. If you discount infants and old timers, you are left with a total possible universe of 60k-80k people that would be in the right ages to even USE the internet, half which likely don't, with 95% of the population never

    • by egamma (572162)

      There are only around 5.000 students at ACU based on their website. Even if their 5000 faculty and employees you are averaging 47 logins per person. Does half the town of Abilene use the university as a hot spot or what. Even with an average of two devices per person that seems like a lot of users. of course you could always throttle which ever band gets say more than 70% of the traffic.

      It says 470,000 connections PER DAY, divided by 5000, is 94. So if you go from your dorm room (1) to the business building (2) to the bible building (3) to the library (4) to chapel in the coliseum (5) to english (6) and back to your dorm room (7), your one device just made 7 connections. If you went back to your dorm room in between each of those events, it would be 20. Now, consider that there are multiple floors and multiple access points per building, and it adds up very quickly. Imagine if someone wen

    • by skids (119237)

      Likely one of two things here:
      1) they are (defensibly) counting all roams from one AP to the next as their own connection or
      2) they aren't exclusively running WPA (e.g. they are doing open +IPSEC) so every jerk who drives by the campus with his gadgets turned on is ending up in their connection table, even if they cannot use the connection. Which is also defensible, because all those negotiations do use the band and also the infrastructure resources.

  • I'm always surprised how often this is described as a 'new' problem. I have a home network in a very highly populated area, I can see over fifty networks from my apartment, and I switched to a dual-band router as soon as they came on the market. I would have thought that planning a university network to work on both bands would have been on the radar for a number of years.
    • I had the same problem in my apartment, there are between 30-50 networks (both residential and business) in range at all times crowding bandwidth, and to make matters even worse, it seems like a lot of them have that "smart switching" technology where they automatically go looking for the least crowded channel. The problem is that there are so many of those routers here that it's like they chase each other up and down the band all day long. I had no idea how bad the problem was until I downloaded a wifi a

  • Channel 14 (Score:4, Interesting)

    by snsh (968808) on Monday October 24, 2011 @03:23PM (#37822210)

    Anyone knowledgeable about the conflict is 2.5GHZ that led the US FCC to limit wifi from using channel 14 (2.484 GHz)?

    According to the FCC spectrum chart [doc.gov] the top of the 2.4 wifi band abuts the "Standard Frequency and Time Signal" Band at 2.5 GHz. What is that used for?

    • Re: (Score:2, Informative)

      by jonbryce (703250)

      Radio controlled watches and clocks use that to set the time. My watch checks that signal every day at 2am and adjusts itself to the correct time.

    • by oneiros27 (46144)

      I assume that would be WWV :

      http://en.wikipedia.org/wiki/WWV_(radio_station) [wikipedia.org]

    • by egamma (572162)

      Anyone knowledgeable about the conflict is 2.5GHZ that led the US FCC to limit wifi from using channel 14 (2.484 GHz)?

      According to the FCC spectrum chart [doc.gov] the top of the 2.4 wifi band abuts the "Standard Frequency and Time Signal" Band at 2.5 GHz. What is that used for?

      Let me Google that for you [lmgtfy.com]

    • Re:Channel 14 (Score:5, Informative)

      by vlm (69642) on Monday October 24, 2011 @04:09PM (#37823032)

      Anyone knowledgeable about the conflict is 2.5GHZ that led the US FCC to limit wifi from using channel 14 (2.484 GHz)?

      According to the FCC spectrum chart [doc.gov] the top of the 2.4 wifi band abuts the "Standard Frequency and Time Signal" Band at 2.5 GHz. What is that used for?

      You're a factor of 1000 too high for WWV.

      The problem with channel 14 is if it were used it would pretty much wipe out the BRS/MMDS service right above the wifi band.

      http://en.wikipedia.org/wiki/Multichannel_Multipoint_Distribution_Service [wikipedia.org]

      MMDS never really went anywhere, which is a shame. For at least 30 years some areas have had some MMDS gear; my local school district linked the schools together in the 80s. Back when a decent pro-grade VCR cost $2500 a $1000 MMDS link between schools to share the VCR sounds like a good idea.

      You'd be crazy to set up a MMDS system now, with the wifi wanna be hackers trying to use channel 14 to get away from the noise and some microwave oven interference. So that chunk of bandwidth is kind of a wasteland that no one can use, more or less.

      Advanced AV stuff like that was kind of the "ipad of the 80s" where merely spending dough on silicon would magically make the kids smarter, or something.

      • by adolf (21054)

        You'd be crazy to set up a MMDS system now, with the wifi wanna be hackers trying to use channel 14 to get away from the noise and some microwave oven interference. So that chunk of bandwidth is kind of a wasteland that no one can use, more or less.

        Watch TV has used it for a long time for subscription TV service, and it's still a popular (though regional) alternative to cable or satellite. They're located not too far from me, and it's fairly typical to see their telltale parabolic reflectors on small tower

    • by bzzfzz (1542813)

      It's part of the MMDS spectrum, which in many communities has been relicensed for wireless data purposes using either 802.16e (WiMAX) or older proprietary systems from Alvarion or Nextnet.

  • This might be troublesome to places that run stand-alone AP's, but anyone who runs a controller-based wifi network knows this isn't an issue at all, considering how easy it would be to create a new SSID on a 5Ghz band and push it out to all APs simultaneously. We run 5508 Cisco controllers, where I work, that support between 500 and 1000 devices connecting at any given time (only about 200 APs between the two controllers). For us to put out a new 5Ghz 802.11a or 802.11n-based SSID would take all of 5 minute
  • I for one was hugely disappointed that Apple’s latest iPhone refresh (iPhone 4S) did not address 5GHz WiFi connectivity. The iPhone 4 has supported 802.11n since it was released last year, but, unlike the iPad, it does not support the 5GHz band, constraining use to the already oversubscribed 2.4 GHz band.

    The end-result is silly: for example, I’m running a 5GHz 802.11n network for all my devices at home, but I’m broadcasting an extra 2.4GHz signal for the sole benefit of my iPhone 4. I hope

    • The iPhone 4S is a huge disappointment in several other regards too.
  • WiFi cabled to switch-router, how about they get a better network designer.

    If that many WiFi spots are cabled to the same nodal switch, then that is just one problem of many.

    Has any one tried a flood-ping at any one of the WiFi spots, I suspect, it would be an avoidable single/few point DOS attack with a good network design.

    • by AmiMoJo (196126)

      Try using a de-auth attack. Makes it impossible for clients to maintain a connection. Leave that running for a few weeks and it will clear our that part of the spectrum.

      Obviously don't do that, it's evil.

  • I'm mainly on my Gripe Of The Month but I sure wish there was some little sliver of spectrum besides this for us commoners. I guess all the Corporation$ have hijacked the good stuff. Though there is white space here and there, though need to either spend lotsa bucks on RF equipment or design/build your own (last option time consuming).
    • Are you not aware of the 5GHz unlicensed bands?

      • Are you not aware of the 5GHz unlicensed bands?

        I'm hanging onto my 900Mhz cordless phone for dear life. I can talk on the phone while surfing the net and using the microwave! Such advanced technology.

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