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Self-locating APs – More than just placing APs on maps

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I was converted from skeptic to believer as I was introduced to Aruba’s Self-Locating AP Technology at Aruba Atmosphere 22. Initially, I didn’t understand the problem it was trying to solve. I got the sense that it was created to reduce the workload of the network administrator, by alleviating the time spent placing APs on maps.  While that part is true, it isn’t the reason this solution was created.  Aruba’s Indoor Location Services solution uses self-locating APs to aims to begin solving the indoor location and wayfinding problem that has plagued the Wi-Fi industry for the last two decades.

The first step in solving this problem is to start with accurate placement of APs on maps. After all, what is the sense in deploying a technology for indoor wayfinding if the accuracy of manual AP placement is off by 5-10 meters on average? If the APs are not accurately placed, the determined location of the client devices won’t be accurate either. One impressive aspect of this solution is that it doesn’t rely on the floor plans at all. Theoretically, it could accurately place all of your APs in space without any floor plans. The system locates APs with latitude and longitude, in addition to placing them on a plane (analogous to a floor).

The more I heard about the solution, the more interested I was in understanding the technical achievements that make it possible. So, how does it work?  There are two primary technologies at play in Aruba’s Self Locating APs. The first is a special type of GPS receiver that already is included in every AP-6xx series AP that refines its location over time. GPS information received by each AP is used collaboratively with all of the other APs in the system. It can actually combine information received by APs on one side of the building with information received by APs on the other side of the building to interpolate or improve a location fix. The combining of this information is only possible because of the second primary technology in the solution.

The second technology is based on 802.11mc and is called Fine Time Measurement (FTM), which can accurately determine the distance between the indoor APs to an accuracy of ~1m. Practically speaking, you wouldn’t expect APs in the center of a building to be able to achieve a GPS lock. The APs that can’t acquire a GPS lock will be located by comparing their location in 3D space to GPS-located “anchor” APs with FTM. FTM also allows the system to improve the accuracy of the GPS-located APs by comparing their location to other GPS-located APs with FTM. In concert, these two technologies allow the system to accurately place your APs on floor plans and create a very accurate foundation on which to build your indoor location system.

One challenging aspect of using GPS to determine AP locations is elevation. GPS has notoriously poor accuracy as it relates to determining elevation. Aruba works around this problem by determining which APs are co-planar (on the same floor), combined with the sequence of the floors. Since the system knows which floor is the lowest floor, based on these measurements, it can determine which APs are on each floor in reference to the floor plans loaded in Aruba Central.

In addition to substantially improving the accuracy of AP placement on floor plans, the solution will share its location information with applications running on client devices by way of Open Locate. Open Locate is an industry-wide initiative to combine all of the ways the Wi-Fi infrastructure can share its location with client devices. In the future, this could allow mobile devices to determine their indoor location solely by participating in the FTM ranging process with the infrastructure APs.

I am very excited to see what this technology brings the industry in the next few years. I love seeing manufacturers truly innovating in a way that could provide an entirely new method of locating Wi-Fi devices indoors. Combining this with other indoor location technologies could bring new levels of accuracy and new indoor location use cases to the entire Wi-Fi industry. I’m honored and grateful to have been part of the launch of Aruba’s Self-Locating APs at Aruba Atmosphere 22.