If you want to know where a wired network device is, you can follow the cable (at least in theory). Wireless devices could be anywhere, so the vendors are vying to make the best way to pin down were a signal comes from - whether it's one of your own devices or a rogue access point you want to get rid of.

There's a lot more to having a location-aware WLAN than this though. The only thing is, no one yet agrees who should provide the service and how it should best be done.

What is it and how does it work?
Location awareness means being able to tell where every wireless endpoint — be it user device or AP — that’s within range of your WLAN environment actually is.

There’s no standard for how this is done: the vendors that support this capability use the RF signal strength to find devices, usually by triangulating signals from multiple APs or separate sensors, and then using their own mechanisms and algorithms for taking into account building effects such as attenuation and reflection to build up a picture of where things are.

This is in most cases superimposed on a graphical representation of your building, and, in the case of APs, tied in to where they are supposed to be, so that if something appears that isn’t supposed to be there, it can be identified on the floor plan to make it easier to find.

Here's three options we know of to offer location:

  • Wireless switch vendors can offer it as part of their system. Airespace includes it as a location tracking option within its overall WLAN management package, the Airespace Control System (read Airespace's White Paper on the subject)

  • Specialist vendors can include it in a wireless management overlay. Such as Newbury Networks’ Wireless Watchdog.

  • Cirond, on the other hand, offers a software-only package that can be used with any AP.

If you decide it’s a useful feature, you’ll have to decide which method you want — which may depend on the APs and wireless switches you already have — as it won’t make sense to try to use more than one.

Why would you want to do that?
As we said, location awareness is being touted as a security method, to detect unauthorised APs or ad-hoc networks within your premises, or to pick up people outside the building trying to listen in. You have to ‘teach’ the system about the perimeter of your building for this to work, and the accuracy can vary—triangulation methods can in cases only manage 10m accuracy, so there’s no guarantee it can differentiate between someone out on the street and a valid user in a room that backs onto an external wall.

If that’s all you want such a system for, you should also consider the alternatives, such as directional antennae, reducing AP power, or the use of reflective screening to keep outsiders out. Or even deploying proper (non-WEP) security to stop anyone from being able to access your WLAN without authorisation.

Similarly, most WLAN offerings now support a mechanism for detecting rogue APs anyway — though in most cases you still do have to manually remove them, albeit just by disabling a switch port — so again, this shouldn’t be the primary reason to invest in location tracking hardware or software.

But as part of your overall WLAN management, it’s more likely to be worth the time and effort. The more comprehensive location tracking systems also offer capacity planning, traffic reporting and trending functionalities, to help you plan your WLAN deployment more effectively.

Coupled with RFID tags, it can also be used to track people and equipment within your campus area. Fit a small transceiver to expensive office equipment and you may not have to spend hours looking for that overhead projector the boss urgently needs, that someone locked in a cupboard for safety just before they went off on holiday. Airespace reports to us that location sensing is already used by some of its hospital clients to track expensive and necessary units such as resuscitation trolleys.

And while it’s unlikely that privacy regulations will allow for people tagging (unless you have a criminal record), it is already being used to track lost kids at Legoland.

Some of these ideas may not be immediately useful to every enterprise, but while the WLAN security aspects are important, they are by no means the only reason you should be looking at the potential for being able to physically track WLAN devices. WLAN security is a hot topic, and rightly so, but there’s no point in adding extra security mechanisms if they don’t add significantly more that you can get from your system already.

Want more: Read a White Paper from Airespace on location awareness.

So where are the benefits of Location-Aware Wi-Fi? Join our forum and tell us.