Android 9 Pie introduced support for indoor positioning by leveraging 802.11mc. Wi-Fi Round Trip Time (RTT) allows the system and apps to “measure the distance to nearby RTT-capable Wi-Fi access points.” Google this week published a “WifiRttScan App” for developers through the Play Store.
Location derived by GPS is not accurate in closed off, indoor settings. Google in the past explored beacons as an alternative, with its latest attempt at indoor positioning leveraging the IEEE 802.11mc Wi-Fi protocol. Accuracy can be within 1 to 2 meters if a device is able to measure the distance to three or more access points. The RTT APIs in Android 9 and later allow any app to take advantage of indoor positioning.
Use cases involve helping people navigate shopping malls, stadiums, conferences, or other suitably large venues. Besides in-building navigation, other new experiences include:
- Fine-grained location-based service: disambiguated voice control (for example, “Turn on this light”)
- Location-based information: (such as “Are there special offers for this product?”)
Published via the “Developed with Google” Play Store account on April 10th, this app is for “developers, vendors, universities, and more” as a “research, demonstration, and testing tool.” It was also released eight months ago through GitHub, but it’s now more widely available.
Developers, OEMs and researchers can use this tool to validate range measurements enabling the development of positioning, navigation and context-aware applications based on the WiFi-RTT API.
The 2.5MB app (and Wi-Fi RTT) requires that users grant the Location permission to display a list of RTT-capable APs by SSIDs and BSSIDs. Tapping will open a granular list of Access Point Ranging Results that notes range (in meters) and latitude/longitude/altitude, if available.
WifiRttScan App is available on the Play Store and requires a supported Android 9+ device.