School Pickup Use Case (update)
It might be helpful to go into a more concrete use case instead of the original backyard example below. Local law enforcement has started cracking down on use text messaging and cell phone use in school zones. This presents a problem for parents picking up kids after a middle school function. Even for those who flaunt the law, the cell tower quickly becomes overloaded when hundreds of kids call their parents at once. The campus is large, with wifi coverage. It seems like it should be possible to write a mobile app that would allow a cell phone user to send a text message containing a list of wifi signal strengths to a webservice. The web service would then create a location fix and push the message to the parent's on board navigation device. The parent would then drive to the correct location on the campus.
Backyard Use Case (original) When I take my laptop into my backyard and choose "view available networks" I see a list of my 4 neighbors. As I walk around, the relative signal strengths from my neighbors changes.
I'd like to stand with my laptop at known locations in my back yard, click on the map and collect points with 4 different signal strengths.
After collecting a lot (but not too many) of these calibration points, I'd like to then write a program that takes 4 wifi signal strength levels and estimates a location in the form of an error ellipse. The signals might be measured using a different device than the one used to collect the original calibration points.
What algorithm should I use?
I do not want to disturb my neighbors by asking them if I can come in and survey the exact location of their router.
I can assume, however, the location of my neighbors routers does not change.