US Patent 8010227 Navigation system with downloadable map data

A system and method are disclosed for providing geographic data to end users' mobile units from a remotely located navigation services provider so that navigation functions can be provided locally on the mobile units. The navigation services provider determines one or more map tile exit points along the route and sends the tile exit points and a set of map tiles to the mobile unit. The mobile unit calculates a route from its current position to the farthest map tile exit point for which map tile data has been received from the navigations services provider.