Received Signal Strength Indicator (RSSI) is another option ... It then colors in your map to give you a general idea of Wi-Fi signal strength throughout. If you're at the center of your home ...

A measurement of the strength of a radio signal being received. In RFID, RSSI is used to determine a tag’s distance, as the signal is stronger from a tag that is closer to the reader antenna.

With the tech giant's idea, a smartphone would download a map of the wireless network signal strength for nearby regions, and it would then feed that info to the vehicle's navigation system.