Wireless coverage in Main Library

Despite the recent increase in wireless capacity in the Main Library, some users are still experiencing problems. We need to gather information about where and when the problems are occuring,  so we can address them. We have a survey, available at go/libwireless to collect the information we need. If you’ve had problems using wireless in the Main Library please take a couple of minutes to complete the survey – annonymously if you like – it’ll really help us out.

2 thoughts on “Wireless coverage in Main Library

  1. Misha

    Hello,
    I think the main issue is just that the internet is excruciatingly slow, I feel like I am still running through 56k modem. For a school like Middlebury this shouldn’t be the case. I don’t really understand because the wired connection is supper fast!

    Reply
  2. Adam Franco

    Misha,

    Here is a bit of an explanation for the wireless problems in the Main Library. Please note that I am not a network engineer and have no involvement in the networking of the college. This is just an overview of the problem as I understand it.

    This issue with the slowness of wireless access in the Main Library isn’t one that can be easily solved by adding more access points or other hardware. A large part of the problem is due to the sheer number of devices trying to connect at the same time on the same frequencies.

    For example, if there are 200 people in the library with laptops and wifi-enabled phones (plus a few other wifi devices like iPod-Touches) there might be 400 or more devices all trying to get internet access over wifi. If the library has about 10 access points, each on a different channel/frequency, that means that each access point might be have 40 clients sharing its bandwidth. Since 802.11g wifi has a theoretical maximum throughput of 54Mbit/s (and a practical average of 22Mbit/s), each laptop or other device can only expect to get ~550kbit/s of bandwidth in a best-case scenario. While this is potentially much better than a 56kbps, its a lot less than the 100Mbit/s you would get through a yellow cable.

    Remember however that 550kbit/s is a best case scenario — with so many devices using the wireless at the same time there is a huge amount of radio interference/noise that dramatically decreases the quality of the signal between the access point and each computer. As well, since there is so much interference, your computer will often have to make multiple requests for a piece of data before it successfully gets it, hurting performance even more. On top of this, even if a laptop is plugged into a network cable, if its wifi antenna isn’t turned off, it is still trying to remain connected to the access point even if most of its data is going over the cable.

    To fix the slow-downs the networking staff can’t just add more access points or turn up the power to them to improve signal clarity, because then the access points would start interfering with each other. As I understand it, the only real solution is to add many many more low-power access points and carefully arrange them so that the ones on overlapping channels are far from each other and don’t interfere. I imagine that this is a major networking project that will take time and resources and lots of testing to solve.

    For those interested in more detail on providing wireless access to large groups, check out this forum on providing wireless for conferences.

    Reply

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