Patent ID: 7071843

Claim:
A navigation system including a mobile unit and a navigation server communicating with each other over a radio communication network, wherein said mobile unit comprises: a communicating unit for communicating bi-directionally with said navigation server over said radio communication network; a positioning unit for determining a self-location of the mobile unit; a control unit for transmitting position information delivered by said positioning unit to said navigation server through said communicating unit, and for acquiring, from said communicating unit, map information for display indicative of a map of a surrounding area including the self-location provided by said position information sent back from said navigation server, to perform map matching between road information included in said acquired map information for display and position information determined by said positioning unit, thereby determining a current position of the mobile unit on a road; and a display unit for displaying a map in the form of an image in accordance with said map information for display and for displaying said current position determined by said control unit on said map displayed in the form of an image, wherein, when having received said position information transmitted from said mobile unit, said navigation server sends map information for display, corresponding to the map of the surrounding area including the self-location of said mobile unit determined by said received position information, back to said mobile unit, wherein said navigation server uses road information to produce optimum route information, and wherein the road information included in the map information for display is formed by data having a smaller capacity than the road information which is for use in producing the optimum route information by the navigation server.