Patent ID: 7912635

Claim:
A terminal unit comprising: a navigation processing unit; a memory unit; the navigation processing unit further including, a route search unit for searching a route from a starting location to a destination by using traffic information stored in the memory unit, the traffic information including a link configuring a route or an area including the link and a link cost, the area being a mesh area partitioned by a predetermined latitude and longitude, and a download request unit for requesting a traffic information distribution server for distributing traffic information to download traffic information relating to a link belonging to the searched route or to an area including the searched route, wherein the route search unit reperforms route search by using the link cost included in the downloaded traffic information when the link cost for the link is included in the downloaded traffic information, and using the link cost stored in the memory unit of the route search unit when the link cost for the link is not included in the downloaded traffic information; and wherein the download unit makes a request for downloading: a) traffic information with respect to all sub-links included within a predicted running duration of the link, and at least one of: b) traffic information of expanding mesh areas, by including a plurality of mesh areas adjacent to the mesh area along the route within the predicted running duration, and c) traffic information of an expanding period of time duration, by adding a predetermined time to the predicted running duration in the mesh area that includes the link.