How Policies Can Help Deal With BYOD-Related Wi-Fi Interference
RF Interference has the ability to really ruin your day – unless you know the symptoms and have the right tools at your disposal. In this series, Wi-Fi expert Craig Mathias discusses problems and solutions to this issue.
Last installment, we discussed possible RF interference sources. Today we discuss the first step in dealing with RF interference, which is to establish local policies. This may seem obvious, but just as users bring their own devices today, they may include a good number of potential wireless interferers as well.
And many of these BYOD devices should probably be banned – wireless headsets and video devices, wireless gaming systems (in the break room or not), and related non-essential, non-business wireless equipment.
The same goes for rogue (unofficial) access points, which may be entirely innocent, but which regardless represent a threat to both network security and the integrity of the airwaves.
So having a set of written policies is vital. These may be included in your security policy, or in a separate IT policies document. Make sure everyone is aware of local rules and regulations. An occasional reminder in the form of a memo or simple e-mail is a good idea. Highly-regulated organizations in banking, finance, healthcare, and retail, for example, may want to conduct short training classes, in a group setting or via e-learning on the Web (or intranet).
Next, while the use of a spectrum analyzer to discover interference sources is always desirable, and can often be used to identify sources of interference that can be eliminated, avoid the temptation to think that manually setting channels and transmit power levels is a good strategy.
Just like modern fly-by-wire aircraft, in which the pilot is really telling a computer what to do and the computer then turns the pilot’s intentions into a series of operations affecting engines, control surfaces, and more, modern WLAN systems are much better at determining optimal RF settings than mere mortal network administrators.
Most control systems are adaptive and will change channels and power settings over time as required. While perfection is impossible for both algorithm and human alike, the WLAN system almost always does a better job in the long run.
That being said, monitoring network utilization using the system management console is always a good idea. Setting alert and alarm levels is a big help in solving congestion and interference problems as soon as possible, but the continual display of key trends is truly valuable.
Ditto for infrastructure-based spectrum-analysis functionality – keep an eye on the trends. Dispatch a PC-based spectrum analyzer as required; such is the best way to determine the precise location of an interferer for brute-force remediation – removal of the offending transmitter.
The bottom line is the identification, localization, and physical remediation of interferers is the best first-pass strategy for most organizations. You may need to take into consideration such potential interferers as engineering labs (who can, admittedly, wreak wireless havoc from time to time) and the increasing presence of IoT devices serving in security, environmental, and related building and administrative functions.
Moving some users from 2.4 GHz. to 5 GHz., often in conjunction with the deployment of 802.11ac, is also a good strategy. There’s a lot more spectrum available at 5 GHz., so the potential for interference, at least in the near term, is less here. The beamforming feature of .11ac is great for improving signal quality and at least partially rejecting interfering signals. Adding additional APs for a denser deployment can also help.
But just how much control can you really have over the airwaves? We’ll dig into that topic next time, in the final installment of this series.
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