Get a WLAN audit done once in a while

The biggest frustration of end users is WLAN interruptions, or poor connection quality when connected wirelessly. This can lead to complaints to IT services.

WHY?

The biggest frustration of end users is WLAN interruptions, or poor connection quality when connected wirelessly. This can lead to complaints to ICT services. Often complaints are then made that the equipment is no good, are these complaints really due to the equipment, or is it more likely that they result from a design that may no longer be in line with the current needs of the end user?

Some practical examples to point this out that we encounter more than once:

  • An end customer has a wireless network in service, installed 5 years ago and this network has never given problems. They purchase new laptops, which no longer have an Ethernet card, but only the latest WLAN chipset available. The company has completely switched to Teams/ZOOM/Webex/... meetings but unfortunately users complain about the quality of calls and video. Probably the WLAN was correctly designed for the needs of 5 years ago, but no longer optimal for the type of device and the type of applications used on it today.
  • The WLAN network was completely redesigned only 2 years ago, but Wi-Fi phones have recently come into use and there are some problems with them when people make calls while walking around with them. Again, the design may not be optimized for Voice over Wi-Fi (VoWi-Fi) and a new Site Survey needs to be done for it so that this can be rectified. WLAN network design involves more than just coverage; here we also look at capacity and user experience.
  • A user complains about the poor coverage at his desk, but if we look at the initial demand, x number of years ago, there was only the need to cover the meeting rooms and not the desks. Now WLAN is becoming more important in the company, so coverage needs to be extended to everywhere.

 

In WLAN audits, I find it important to know this history, be it with initially our own customers, be it with new customers. What was the initial installation for? Where did Wi-Fi need to be available initially? Where does Wi-Fi need to be available now? What applications were and are now being used on the Wi-Fi? Answers to these questions can provide insights into why certain configurations happened, or why there is currently a poor user experience.

However poor WLAN quality is not always solely due to a change in the end customer's needs. The RF environment may also have changed completely from the initial measurements.

  • There have been renovations that suddenly add an extra wall, or a wall has disappeared.
  • The whole network should be in order before a move takes place, but after a move there are suddenly cabinets (often metal as well) that can cause a big difference due to signal reflection, among other things.
  • There is a neighbouring company that has a new WLAN solution and is using overlapping WLAN channels or the same WLAN channels.
  • There is a new solution installed within the own company or at a neighbouring company that also uses the same frequency bands (therefore not always a WLAN solution)

 

WHAT CAN ACTUALLY BE DONE ABOUT THIS?

Often when I do a WLAN audit at companies about their recent WLAN infrastructure (mainly Aruba), we often come to the conclusion that a lot can already be straightened out with adjusting certain settings, or mounting APs correctly. But looking at the RF spectrum on site is also very important (as also said earlier). The latter often shows problems that can sometimes be avoided by disabling certain channels or possibly the 2.4GHz band. The most common problems of the latter are:

  • Too many APs transmit in the 2.4GHz band, causing co-channel interference. This basically amounts to APs interfering with each other because they are not quite tuned to each other. Turning off this band on some of the APs often does wonders.
  • A separate service that sits within the same corporate walls has their own low-cost Internet line (example: ICT service that has its own ADSL for testing), but the routers that are installed also have their own Wi-Fi that is broadcast; such devices often broadcast this Wi-Fi in channels that are interfering or overlapping (mainly in 2.4GHz)
  • All devices can handle 5GHz, and there is a lot of interference in the 2.4GHz band; On the SSID where only corporate devices connect, let them transmit only in the 5GHz band; but since it is often not as far to be received, sometimes an AP needs to be added.

In various industries we hear all the time, "Can you create another SSID because we want to split our networks" or "We are getting a new device on the network and it needs a separate SSID. Well there again I believe (and many WLAN engineers will agree with me) to have as few different SSIDs in the air as possible. By default, I will always suggest limiting WLANs to:

  • A corporate network (802.1X authentication)
  • A Guest network (captive portal)
  • Optionally: a VOIP network for telephony
  • Optional: an SSID with preferably the Aruba MPSK technology (proprietary, but similar technologies exist with other manufacturers) for devices that do not have 802.1X authentication capability and still need to be able to securely access the network. The advantage is that each device gets its own pre-shared key to prevent the passing of these keys.

More than this number of WLANs is not needed in most cases; especially if this can be done in combination with a decent authentication server such as Aruba ClearPass, among others.

These are just a few aspects that are looked at during a WLAN audit. In case of a new installation a pre-installation survey is always carried out, either on plan or via a site visit with measuring equipment. This is to determine how many APs, what type of APs are needed, where they should be placed, etc. After an installation, a verification survey is then ideally conducted to determine if the installation meets the requirements. These measurements can then be taken as a baseline for any subsequent WLAN audits. It therefore indicates that a WLAN audit is interesting to perform on a regular basis, especially since technology and end-user expectations are constantly changing.

 

Thomas De Smedt