What is WiFiSLAM?

What is WiFiSLAM?  Perhaps you have noticed that GPS location services are not exactly precise.  A GPS can be accurate within about 10 meters, but signals are affected by obstructions such as buildings, trees, fences, cables etc.  Furthermore, GPS signals don’t reach inside buildings very well.  If you have ever tried to make it from registration to radiology in a big city hospital, you know that an indoor map would be a welcome thing.

WifiSLAM is a start-up tech company that wants to “allow your smartphone to pinpoint its location (and the location of your friends) in real-time to 2.5m accuracy using only ambient Wi-Fi signals that are already present in buildings.”

How does WifiSLAM do that?  SLAM stands for Simultaneous Localization and Mapping. WiFiSlam gathers location information by recording “trajectories” from sensors on the phone including the accelerometers, gyroscopes and magnetometers.  WiFiSlam’s technology uses data collected based on relative Wi-Fi signal strength to judge where the smartphone user is in a building.  If enough people walk through a building with Wi-Fi activated on their smartphones, a map will begin to form of the building interior.  Raw trajectories, using inertial sensors of one or many phones, help to form a map, combined with wifi data, of the inside of a building.

The buzz around WiFiSLAM grew loud in March, when Apple bought the start-up.  Apple had some customer complaints about its mapping service when it came out last year.  Apple may be trying to beef up its mapping ability and edge out Google, who already has indoor maps of certain locations like airports, hotels, museums and shopping malls.  A New York Times article called the Apple vs. Google rivalry “a battleground,” and a Reuter’s article stated, “Big tech companies such as Apple and Google have been racing to provide more and better map applications for users.”

There is another potential use for WiFiSLAM’s tech than simply indoor mapping.  Alex Romanov, CEO of Ontario’s iSIGN Media, sees it as an entry into “proximity marketing.”  Romanov wrote in Upstart Business Journal, “Proximity marketing takes advantage of the fact that consumers are much more likely to respond to offers they receive within sight of the item being sold. Customers who walk into a grocery store or restaurant have indicated an interest in purchasing food by their very presence: What better time to offer them a digital coupon?”  Ads or coupons could be transmitted via Wi-Fi or Bluetooth directly to smartphones, and would not require collecting any identifying information from the smartphone user.

If Apple does incorporate WiFiSLAM’s technology into the iPhone, you could check your phone to find the nearest restroom in a stadium and get an ad for the nearest hotdog stand at the same time.