On 9/9/13 6:41 PM, Eric Rescorla wrote:
1. How do I bootstrap? I turn on my device and want to get the coordinates of the aps I see. That requires a lat long for neighbors. What now?
The device would scan for nearby APs and send the hash of each AP's MAC and SSID to our location server. Our server would not need to worry about the hash of hashes pairs because that would only be used for published data. The server would return an estimated latitude, longitude, and accuracy (radius in meters) of the device among the APs.
The simple approach for predicting the device's position is trilateration using a weighted average of the nearby APs' positions. A more robust approach is a grid-based approach where the server divides the world into squares and knows which APs have been seen from which squares.
The device might be able to cache a portion of the geo data (e.g. part of the current city) to allow offline geolocation.
2. As asked previously will the db be published or query able?
We are investigating both a web service API and a downloadable database. We are collecting position data for both Wi-Fi access points and cell towers. Depending on privacy protections, if we can't publish the whole database to the world, we can publish just the cell tower data to the world and possibly make the Wi-Fi data available only to trusted researchers.
3. What is the lat/long resolution? How is it measured?
This depends on the GPS of the device used to collect the data, but our database stores 7 decimal places (less than one meter resolution).
chris _______________________________________________ dev-security mailing list dev-security@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-security
