XPost: comp.mobile.android, alt.comp.os.windows-10   
   From: wolf@greenblatt.net   
      
   On Mon, 11 Nov 2024 22:17:24 +0000, Roger wrote:   
      
   > On Mon, 11 Nov 2024 16:19:28 -0000 (UTC), Andrews   
   >  wrote:   
   >   
   >>4. Instead of relying on signal strength measurements, Wi-Fi RTT   
   >>   with FTM measures the time-of-flight (ToF) between an RF packet   
   >>   sent from your phone to several nearby APs. While Wi-Fi RTT with   
   >>   FTM worked over both the standard 2.4 & 5GHz bands, it was never   
   >>   widely deployed in the field, so you¢ve probably never used it   
   >   
   > This may be a silly question but why would a phone be sending   
   > anything to APs that it doesn't know and therefore cannot use?   
      
   https://query.prod.cms.rt.microsoft.com/cms/api/am/binary/RWEMFM   
      
   Indoor positioning technology update (2021)   
      
   Introduction:   
   Which is the best indoor positioning technology for mobile apps?   
      
   Indoor positioning technology for smartphones is developing rapidly, driven   
   by the demand for indoor mapping, indoor tracking, and real-time location   
   analytics. So we regularly publish tech updates to help you keep up to   
   speed with the latest changes.  For each technology, the costs need to be   
   balanced against the delivered accuracy.  For all the talk about sub-meter   
   accuracy, it's seldom required. For indoor navigation systems, an accuracy   
   of a few meters is needed.  There are lots of exciting technologies on the   
   horizon.  But for 2021 we recommend sticking with a Bluetooth beacon   
   infrastructure, combined with inertial data. This technology provides   
   mobile apps with a location accuracy of 2 to 5m. It's quick and cheap to   
   install and configure.   
      
   The great promise of Wi-Fi positioning is that it leverages existing   
   infrastructure.  However, iOS doesn't give access to WiFi signal strengths.   
   So positioning has to take place on the infrastructure, not the phone. And   
   this means there's no access to inertial information. This greatly limits   
   the accuracy that WiFi signal strength positioning can achieve.  If   
   802.11mc (RTT) or 8.2.11az reach mass adoption,this could all change. These   
   technologies use time of flight ranging instead of signal strength, making   
   them much more accurate. Inertial information is still helpful,but it's not   
   so important. So WiFi-based location may become a more attractive   
   technology.  For 2021, these technologies aren't yet viable, mainly because   
   iOS doesn't support RTT.   
      
   Currently the best balance between cost and performance.  Installation is   
   needed.  But the beacons are low-cost and battery-powered,with battery life   
   measured in months or even years. So both installation and ongoing   
   maintenance are minimal.  Bluetooth beacons alone don't provide great   
   accuracy.  But when combined with inertial data, the accuracy is good   
   enough for almost every use case.   
      
   Specialist technologies like Angle of Arrival Bluetooth, UWB or ultrasound   
   may achieve 1m accuracy. This is impossible using Bluetooth or WiFi. But it   
   comes at a cost. The hardware makes deployment much more expensive and more   
   complex.  And it's not yet supported on enough phones.   
      
   Much more accurate indoor positioning can be achieved if the distance   
   between anchors and mobile devices is measured with precision.  Technology   
   options are increasing, and are starting to become available on   
   smartphones. For instance, WiFi RTT times the signal rather than using   
   signal strength,and is capable of sub-meter accuracy. It's available now on   
   Android phones.   
      
   --- SoupGate-Win32 v1.05   
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