Considerations for Location Services

I’ve got a client that need to become PCI compliant. As part of their PCI compliance they want to be able to detect and locate rogue devices on their network. My biggest obstacle is that the client has several offices throughout Australia and not one office has more than two Access Points per floor.

Below is the WLAN design considerations for Location Services which would make it possible for the client to accurately locate rogue devices.

Minimal Signal Thresholds

For devices to be tracked properly, a minimum of three access points (with four or more preferred for better accuracy and precision) should be detecting and reporting the received signal strength (RSSI) of that device being tracked. It is preferred that this detected signal strength level be -75dBm or better.

Access Point Placement

Here are the requirements to adhere to:

  • Perimeter placement – In a location-ready design, it is important to ensure that access points are not solely clustered in the interior and toward the centre of floors. Rather, perimeter access points should complement access points located within floor interior areas. In addition, access points should be placed in each of the four corners of the floor, and at any other corners that are encountered along the floor perimeter.
  • Triangulation – As mentioned before you need at minimum three Access Points for Location Services but it is important that these APs are not placed in a straight line but rather in a triangular format while using the perimeter of the building as the diagram below indicates.

LocationServices

  • If possible, mount antennas such that they have an unencumbered 360º view of all areas around them, without being blocked at close range by large objects.
  • The distance between deployed access points can impact location performance, as well as the performance of co-resident voice and data applications. From a location perspective, while location tracking inter-access point spacing requirements tend to be relatively flexible and supportive of the coverage needs of underlying applications, very small or very large inter-access point separation distances are usually best avoided.

Determining Location Readiness

I would suggest AirMagnet Survey Pro to do your planning for Location Services and by using AirWise within the software you will be able to verify if signal coverage, multiple AP signal coverage and data rates are sufficient for Location Services. AirWise will provide you a Pass/Fail and % of Good Area regarding signal and data rates.

The end result is two AP’s per floor won’t give you Location Services.

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Considerations for Location Services

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