Navigation system acquisition and use of cellular coverage map data

1. A method comprising:

detecting, at a mobile device, on a first date at a first time of day, a first wireless network signal strength that is current while the mobile device is at a first geographical location;

storing, in the mobile device, a first mapping between the first geographical location, the first wireless network signal strength, the first date, and the first time of day;

detecting, at the mobile device, on a second date at a second time of day, a second wireless network signal strength that is current while the mobile device is at a second geographical location;

storing, in the mobile device, a second mapping between the second geographical location, the second wireless network signal strength, the second date, and the second time of day;

determining, at the mobile device, for each particular area of a plurality of areas within a region, a quality of mobile communication that is possible within that particular area based at least in part on historical signal strength data that the mobile device alone has measured relative to signals that the mobile device has detected during previous trips that the mobile device has taken through that particular areas;

based at least in part on the quality of mobile communication that is possible within each particular area of the plurality of areas, a selection device selecting a particular route from a plurality of routes each ending at a same destination; and

providing the particular route to a display device;

wherein the historical strength data includes the first wireless network signal strength and the second wireless network signal strength; and

wherein the plurality of areas includes the first geographical location and the second geographical location.

2. The method of claim 1 , wherein providing the particular route to the display device comprises presenting the particular route on a display of the mobile device.

3. The method of claim 1 , wherein providing the particular route to the display device comprises transmitting the particular route from the mobile device to a vehicular navigation system with which the mobile device is communicatively coupled.

4. The method of claim 1 , wherein determining the quality of mobile communication that is possible within a particular area comprises determining the quality based on multiple measurements of cellular signal strength by the mobile device within that particular area at different times.

5. The method of claim 1 , wherein determining the quality of mobile communication that is possible within a particular area comprises determining the quality based on a proportion of dropped telephone calls occurring relative to the mobile device within that particular area at different times.

6. The method of claim 1 , wherein determining the quality of mobile communication that is possible within a particular area comprises determining the quality based on a measured bandwidth of packetized data communications occurring relative to the mobile device within that particular area at different times.

7. The method of claim 1 , wherein determining the quality of mobile communication that is possible within a particular area comprises determining the quality based on a measured proportion of data packets retransmitted during packetized data communications occurring relative to the mobile device within that particular area at different times.

8. The method of claim 1 , wherein determining the quality of mobile communication that is possible within a particular area comprises determining the quality based on quality measurements made within that particular area by a plurality of separate mobile devices.

9. The method of claim 1 , wherein determining the quality of mobile communication that is possible within a particular area comprises determining the quality based on quality measurements made within that particular area at a time of day that is within a specified range of a time of day at which the determination of the quality is made.

10. The method of claim 1 , wherein determining the quality of mobile communication that is possible within a particular area comprises determining the quality based on quality measurements made within that particular area on a day of the week that is the same as a day of the week on which the determination of the quality is made.

11. The method of claim 1 , wherein determining the quality of mobile communication that is possible within a particular area comprises determining the quality based only on quality measurements made for a wireless network of a cell phone company that is the same as a cell phone company that the mobile device exclusively uses.

12. The method of claim 1 , further comprising:

measuring, at the mobile device, a current quality of mobile communication within an area in which the mobile device is currently located; and

transmitting the current quality of mobile communication wirelessly over a network to a remote server.

13. The method of claim 1 , wherein selecting the particular route from the plurality of routes each ending at the same destination comprises determining, at a vehicular navigation system that is communicatively coupled to the mobile device, for each of the plurality of routes, a separate score that is based at least in part on wireless network quality measurements of multiple areas through which those routes pass.

14. The method of claim 1 , wherein selecting the particular route from the plurality of routes each ending at the same destination comprises determining, at a vehicular navigation system that is communicatively coupled to the mobile device, for each of the plurality of routes, a separate score that is based at least in part on: (a) wireless network quality measurements of multiple areas through which those routes pass, (b) lengths of those routes, and (c) estimated times required to travel those routes.

15. The method of claim 1 , further comprising:

periodically requesting refreshed wireless network signal strength map data over a wireless network from a remote server;

periodically receiving the refreshed wireless network signal strength map data at the mobile device; and

periodically transmitting the refreshed wireless network signal strength map data from the mobile device to a vehicular navigation system.

16. The method of claim 1 , further comprising:

the selection device selecting a second route from a plurality of routes ending at the destination based at least in part on refreshed wireless network signal strength map data; and

providing the second route to the display device while the mobile device is traveling along the particular route;

wherein the second route differs from the first route.

17. A method comprising:

determining, at a mobile device, for each particular area of a plurality of particular areas within a region, a quality of mobile communication that is possible within that particular area;

determining, for each particular road segment of a plurality of road segments within the region, and based at least in part on the possible quality of mobile communication determined for an area in which the particular road segment at least partially occurs, a quality of mobile communication that is possible on that particular road segment;

presenting, on a display, a map that:

includes a gradient reflecting a weakening of a wireless network signal as a distance increases from a point of origin of the wireless network signal within a region of the map and

indicates qualities of mobile communications that are possible on road segments within the plurality of road segments.

18. The method of claim 17 , further comprising:

for each particular road segment of the plurality of road segments, coloring that particular road segment with a color that is based at least in part on the possible quality of mobile communication determined for the area, of the plurality of areas, in which that particular road segment occurs.

19. The method of claim 17 , further comprising:

determining a current geographical location of the mobile device;

measuring a current wireless network signal quality at the current geographical location; and

wirelessly transmitting, over a network, to a server that is remote from the mobile device, data that maps the current wireless network signal quality to both the current geographical location and a current time at which the current wireless network signal quality was measured.

20. The method of claim 17 , wherein determining, at the mobile device, for each particular area of the plurality of particular areas within a region, a quality of mobile communication that is possible within that particular area comprises requesting, over a wireless network, from a server that is remote to the mobile device, wireless network signal strength map data that the server has collected from a plurality of separate mobile devices.

21. A method comprising: storing, on a non-transitory computer-readable memory, instructions which, when executed by one or more processors, cause the one or more processors to perform:

detecting, at a mobile device, on a first date at a first time of day, a first wireless network signal strength that is current while the mobile device is at a first geographical location;

storing, in the mobile device, a first mapping between the first geographical location, the first wireless network signal strength, the first date, and the first time of day;

detecting, at the mobile device, on a second date at a second time of day, a second wireless network signal strength that is current while the mobile device is at a second geographical location;

storing, in the mobile device, a second mapping between the second geographical location, the second wireless network signal strength, the second date, and the second time of day;

determining, at the mobile device, for each particular area of a plurality of areas within a region, a quality of mobile communication that is possible within that particular area based at least in part on historical signal strength data that the mobile device alone has measured relative to signals that the mobile device has detected during previous trips that the mobile device has taken through that particular area;

based at least in part on the quality of mobile communication that is possible within each particular area of the plurality of areas, a selection device selecting a particular route from a plurality of routes each ending at a same destination; and

providing the particular route to a display device;

wherein the historical strength data includes the first wireless network signal strength and the second wireless network signal strength; and

wherein the plurality of areas includes the first geographical location and the second geographical location.