HPE Aruba Networking Blogs

A paradigm shift in wireless LAN-based location tracking 

By Keith Parsons, Contributor

I still remember the moment in time I first understood the term ‘Paradigm Shift’.  I was already a full-grown adult, with children and a university degree and finally found some time to read a short story in the book “Seven Habits of Highly Effective People” by Stephen Covey (pages 30-31) in which he describes a shift in his paradigm, or world view. 

I had a like experience at Aruba Atmosphere 2022 in Las Vegas last month with respect to their announcements concerning Aruba’s new location solution.  

After first hearing a marketing presentation on yet one more New Thing in Wi-Fi based location tracking solutions. I was ready and primed to be extremely skeptical.  

First, a bit of background. 

Over the past two DECADES I’ve lived through, learned, installed, fixed, and removed a wide variety of Real Time Location Solutions (RTLS)… As have many of us who have been in the Wireless LAN industry.  

Entire companies have launched, thrived, declined, then failed over these past twenty-plus years of RTLS. The siren song of being able to find and track people and things has been so tempting - and continues to be as we attempt to solve this known demand with our customers. 

In the paradigm shift story from Stephen Covey, he hears a single sentence from a distraught father on a New York subway car and it changes his entire outlook on the situation.  

For me, my paradigm shift on location tracking came during a presentation by Stuart Strickland and Chuck Lukaszewski. In a single sentence, they turned the entire world of Wi-Fi based location tracking upside down and my world view changed.  

The trigger sentence was: “this new solution was NOT based on any pre-existing map or floor plan, but instead used the international standard of latitude and longitude.” Let that sink in for a minute…  

I’ll wait. 

OK, it took me a couple of minutes as well to comprehend what that seemingly small difference means to location tracking.  

No longer are our RTLS systems based on some imported map or floor plan, but instead can work WITHIN the world’s existing navigation structures.  This does mean some fundamental changes in how we go about doing RTLS within the Wireless LAN community. 

First, let me talk about what it is NOT…  

It does NOT mean “Indoor GPS” 

Though the new Wi-Fi 6E access points from Aruba do contain GNSS chipsets and can use these ‘location’ chips to self-locate while indoors, this does NOT mean this Aruba solution offers “Indoor GPS” to your customers’ client devices. 

Sidebar Note: What is the difference between GPS and GNSS? GPS traditionally refers to the North American Global Positioning System. Global Navigation Satellite System or GNSS refers to the International Multi-Constellation Satellite System. GNSS typically includes GPS, GLONASS, Baidu, Galileo and other constellation systems.  

When people refer to GNSS, they are referring to all available satellites for global positioning. 

It does NOT mean “No more Surveys” 

Though this solution of ‘self-locating’ access points - if you have either all Aruba AP-500’s or AP-600 series access points - does not mean the variety of ‘surveys’ we have been doing for decades suddenly disappear. 

There has been a lot said about the terrible word ‘survey’ when referring to things we do in the WLAN community. Predictive designs, AP on a Stick designs, Post-Install Validation and Troubleshooting all will continue as they have in the past.  

If you were a company who used the word ‘survey’ to include the process of documenting access point locations on a map… then perhaps this new self-locating access points may save that one type of ‘survey’. Thus RTLS surveys may now be eliminated. 

It does NOT mean “Smartphones now know where they are indoors” 

In the beginning… Yet, this solution does offer a much better baseline for software developers to work from. Including the ability for certain OS vendors who use a generic call to the OS to ‘find my location’ that would allow for to OS to switch between different forms of location tracking using standard latitude/longitude metrics. See above for NOT Indoor GPS 

What it does mean… 

This new paradigm shift does mean Aruba’s new AP-6xx series Wi-Fi 6E access points will have the ability to know where they are in the world, even indoors. 

This means they will be ready to implement Standard Power after the FCC approves the process since they require 6GHz capable access points to auto locate themselves to meet the Standard Power requirement.  

Additionally, those who have an installed base of Aruba’s AP-500 series access points can also use this new technological solution to auto-locate within VisualRF and have access to these new location features. (With some additional manual placement of anchor access points) 

This also means Aruba is now offering this to the world as an Open Locate initiative so the entire community can benefit and work with this to help solve the location problem we have been working at for decades - but this time together on using a global standard reference.  

How it works 

This is a very rough review of the process. Please read further information from Aruba’s website, Aruba Atmosphere session presentations, and product information for more details and descriptions.  

Since the beginning of navigation, we needed at least two things to find where we were located. First a fixed known location, and second the differences between that known location and where we are now.  

Pre-GPS, navigators used stars, the Sun, and a whole lot of math to figure these things out.  

For this new location solution from Aruba, the first step is to have a handful of AP-600-series access points, with built-in GNSS chips work to find out where they are in the world.  

We’ve had issues with indoor GPS, basically forever. Since the GPS satellites are thousands of miles up in the sky, and their radio signals are extremely weak, and can be susceptible to multipath and attenuation issues indoors.  

This new Aruba location system addresses these a couple of ways. First, they take their time to get it right. Satellites pass overhead and for an indoor access point, may only have a brief, and possibly obstructed view of a satellite’s path across the sky. Yet unlike handheld GPS devices or smartphones with internal GPS, these access points can take their time and wait… wait for hours instead of seconds to acquire these signals. 

Additionally, and very importantly, all these GNSS chipset equipped access points can TALK with each other via Aruba Central. Share information about the satellites they see, learn from others about precise timing triggers, and home in on even more satellites as they pass overhead. 

This is NOT about speed… it is instead all about accuracy.  After a few hours a handful of access points learn where they are in the world. With an accuracy of 1 meter! 

Next – and while the other is going on – ALL the access points use another 802.11 standard, perhaps not used very much by others, but a standard nonetheless, that supports something called Fine Timing Measurement. This FTM figures out the approximate distances between access points.  

At this point there is a lot of math going on. Matrix math to figure out the best fit for the FTM measurements while working with the fixed latitude/longitude of those handful of fixed location access points.  

In the end, all the access points in this group will know their latitude and longitude within 1-2 meters of accuracy and can then Auto-Place themselves on a floorplan in VisualRF.  

Net Result 

After all this technology and with lots of math – Aruba access points will know where they are in the world with very precise latitude and longitude estimates. 

What about Altitude? 

GPS systems have been notoriously bad at accurate height measurements, especially when the metric has been tied to a mean sea level as the baseline altitude. It may be possible to overlay the data collected from GNSS data with geodesic datasets and calculate somewhat accurate and useful height above elevation measurements.  

Instead, Aruba has access to other information found during the FTM calculations to place groups of access points in ‘layers’ – so all AP’s in a given floor will already be grouped together, and this tied with floor-based naming conventions as a check and balance can do quite well in layering access points on their appropriate floor. 

Sidebar Note: The current FCC requirement for automatic geolocation of 6GHz Access Points only applies to a 2D or latitude and longitude to meet their Standard Power requirements.  While elevation is also required to be sent to the AFC System, the rules allow this to be manually set by an installer. 

What is next? 

This was only the first announcement of this new Aruba location solution. There will be more solutions coming, more integrations with client device OS vendors, as well as integration with other RTLS software solutions.  

We now live in a world where our paradigm concerning how indoor location works has been drastically changed for the better! 

 A couple of resources for further study: 

Self Locating Wireless Access Points Overview 

Self Locating Access Point Solutions Overview PDF