Factors affecting Wi-Fi service

Owned by Jia Wen Li
Last updated: Mar 22, 2023 by Rohan Raghavan
7 min read

The University of Waterloo operates one of the largest campus Wi-Fi services in Canada, with over 5,500 Wi-Fi access points (APs) serving over 30,500 people per day.

We do everything we can to ensure a good user experience, from commitment in staff time and budget to campus Wi-Fi infrastructure and service, use of leading technology, a validated design approach,  infrastructure monitoring, and ongoing quality assurance.  For more information about the University’s role in providing campus Wi-Fi service, please read Campus Wi-Fi infrastructure and quality assurance.

If you are having difficulty with the University’s Wi-Fi service, please see Connecting to the eduroam wireless network.

For more information on the factors that affect Wi-Fi service, and what you can do to receive the optimum experience, please read on…

What is Wi-Fi?

Wi-Fi is communication over the air, using radio waves. It includes end user devices (e.g. laptops, smartphones), radio frequency spectrum, and Wi-Fi and network infrastructure including connectivity to the Internet.

Wi-Fi – what can influence service?

Wi-Fi service is affected by all components of the service, including:

  • End user devices

    • Wi-Fi card and drivers in smartphone or laptop.

    • Single band (2.4GHz) devices may experience poorer service in high use areas due to sharing limited number of channels, and interference.

  • Radio Frequency Spectrum

    • Interference from non Wi-Fi devices and ‘Rogue’ APs.

  • Wi-Fi and Network Infrastructure

    • coverage

  • Policies that influence service

    • bandwidth caps

    • requiring a password

  • Wi-Fi technology limitations

    • 2.4GHz band only has 3 usable channels

If you are experiencing a problem…

  • How would you know if the issue is on your device, is caused by interference, is due to a coverage gap, or high usage in the area, or something else?

  • You probably won’t know, so report the issue, and/or visit a Service Desk, so everything can be investigated.

  • In almost all cases, the investigation starts with the end user device itself, checking drivers and settings.

  • If you would like to you can submit a Wi-Fi incident report

  • If you are using a single band (2.GHz only) laptop or smart phone, next time you upgrade be sure to get dual band (2.4GHz and 5GHz) !

But what are the biggest issues, really ?

We do everything we can to ensure the Campus Wi-Fi and network infrastructure is performing properly, for more information read Campus Wi-Fi infrastructure and quality assurance. But that only covers a fraction of the overall service. Read on...
 

End user devices

  • Issues on end user devices (laptops, smartphones, notebooks, etc) can affect the quality of Wi-Fi service.

  • Driver bugs and poor implementations can affect service, even if the device works fine on a home Wi-Fi network.

    • Home Wi-Fi networks use WPA PSK while enterprise Wi-Fi networks use WPA2 Enterprise, the latter being harder to implement correctly.

  • Example: Intel's Wi-Fi adapters connectivity issues continue

If you are experiencing a problem on your device…

  • Ensure the drivers are up to date.

  • Do some web searches of your computer make/model and/or Wi-Fi chipset, plus the text wireless problems (or equivalent) to see if anyone else is having a problem.

  • And/or take the device to a campus IST Service Desk.

  • If you are using a single band (2.GHz only) laptop or smart phone, next time you upgrade be sure to get dual band (2.4GHz and 5GHz)!

Interference

  • Wi-Fi uses radio frequency to communicate between the access points and user devices.

  • It uses unlicensed frequency spectrum.

  • The University has guidelines regarding use of the Wi-Fi spectrum.

  • There are significant sources of interference, particularly on the 2.4GHz band, from:

    • Rogue (or private) access points installed without following the approval process.

    • Microwave ovens.

    • Many models of cordless base station phones.

    • Nearby access points of our own on the same channel (this is called co-channel interference, and is a particular problem on the 2.4GHz band where there are only 3 non-overlapping channels).

  • When another device is using the same frequency as UWaterloo’s Wi-Fi in an area, even at low power levels, Wi-Fi in the area can stop working until the interference is gone.
     

Interference from Rogues

  • ‘On channel’ Rogues, that is rogue access points using the same channels (e.g. 1,6,11) as our APs, are able to gracefully share the bandwidth with our APs in some cases,  because the rogues and our APs recognize and respect each others control frames.

  • However, the bandwidth is still shared between the rogues and our APs.

  • And there is still increased potential for communications to be garbled requiring retries in the presence of on channel rogues.

  • If there are more than a few rogues in an area, even if they aren’t doing anything, significant bandwidth can be used by the beacon frames, which are broadcast repeatedly at the lowest data rate (1mbps for ‘b’).
     

Off channel Rogues and non Wi-Fi interference

  • Rogues not operating on the usual channels completely disrupt our Wi-Fi in the area (and vice versa), and they don’t recognize each others control frames.

  • They just see radio noise, garbling the traffic, then try re-transmitting.

  • Similarly, non Wi-Fi interference (e.g. microwave ovens and cordless base station phones) can completely disrupt Wi-Fi operating at the same frequency.
     

Further reading on interference

…The technical support engineers at a major Wi-Fi infrastructure vendor reported to Cisco that in a recent service call to a major customer they found almost 20 sources of interference, contributing to over 50 percent of the problems on the customer's Wi-Fi network…

 

Other university’s experience with interference can be found online

…Interference also plays a major role in the quality of the user experience. The radio frequencies used in Wi-Fi are also used by many other types of devices. These devices include cordless phones, wireless headsets, wireless microphones, wireless cameras, etc. When these devices are in operation in the same vicinity as a Wi-Fi network, they can cause interference. Interference can also come from sources such as microwaves. The presence of interference can result in a client showing a connection but not being able to perform network operations, slowing down network operations, or completely disconnecting the client from the wireless infrastructure. Interference is often transient, which makes it difficult to find the source…

…With all University-owned housing covered by wireless Internet service, you may be wondering why your connection is sometimes spotty. Rather than call the NUIT Support Center, you might think you can solve the problem yourself (or with a somewhat tech-savvy roommate) and install a personal wireless router in your room.

Guess what? You just killed the Internet for the rest of your hall.

Ok, that may be a slight exaggeration, but with the way large wireless networks like Northwestern’s are set up, individual wireless routers hog a large portion of the available Wi-Fi frequency space and interfere with the University-supplied Wi-Fi network, leaving your hallmates cursing your name when their connections drop…

 

Interference - what we are doing

  • Our Wi-Fi system detects interference, and can adjust the channel of the AP automatically in some cases.

  • But…

    • There are only 3 channels in the 2.4GHz band.

    • There are minimal options for working around interference.  For example the leakage from a typical microwave oven is 30 times more powerful than the average laptops Wi-Fi radio.

    • Unless someone finds and removes (or shields) the interference, it can continue to cause Wi-Fi performance problems.

  • We have updated the guidelines for use of the wireless spectrum, with both Computing Technology and Services Committee and University Committee on Information Systems and Technology support.

  • We have activated some features in the Wi-Fi system to block access to non approved Rogue APs (where possible).  But this does not eliminate the interference from beacon frames.

  • We have acquired directional antenna equipment to start to locate interference sources, with a goal of asking the owners of such sources to remove it, or change to non interfering technology (e.g Dect 6.0 cordless base station phone to remove 2.4GHz base station phone).
     

 

Interference - Memo to the campus community

To: University of Waterloo Campus Community

From: Bruce Campbell, Director, Technology Integrated Services (TIS)

Date: November 13, 2013

Re: Interference from private routers and other sources affecting campus Wi-Fi service

Background

The University has made major investments in upgrades and expansion of the campus Wi-Fi service (eduroam), a reflection of the importance of this service to students, faculty, and staff. The University makes a strong commitment in staff time and budget to ensure this service continues to meet the needs of the campus community.

Issues

We are experiencing problems with radio frequency interference from wireless routers, Wi-Fi Access Points (APs), wireless printers, and some other devices, installed in private offices or labs, to the extent that we cannot provide dependable Wi-Fi service near those areas.

How you can help

We request that anyone who has set up a wireless router or mobile hot spot in their office or lab disable this device, and use the University provided Wi-Fi service. If this service does not meet your needs, please contact me to discuss options for meeting your requirements in ways that do not disrupt Wi-Fi service for other users. We also request that anyone who has set up a wireless printer, AirPort Time Capsule, wireless projector, or similar device, disable the wireless feature and use a cable, to avoid disrupting Wi-Fi service for other users.

IST's role

In the coming months, staff from Information Systems & Technology (IST) will visit campus buildings with equipment to locate remaining devices which interfere with the campus Wi-Fi service. They will ask owners of this equipment to disconnect it, or to move to a technology which does not interfere with Wi-Fi. As always, our staff members are available to assist with a transition to non-interfering technology.

Additional information and obtaining assistance

For additional information, please see the University's wireless guidelines.

For assistance using the University's Wi-Fi network, you may contact a Faculty service desk or the IST Service Desk.

Bruce Campbell

Director, Technology Integrated Services

Information Systems and Technology

University of Waterloo

519-888-4567 ext. 38323

bruce.campbell@uwaterloo.ca