NAVIGATION APPARATUS, SYSTEM AND METHOD THEREFOR, SERVER, NAVIGATION PROGRAM FOR CLIENT, AND NAVIGATION PROGRAM FOR SERVER

摘要

PROBLEM TO BE SOLVED: To provide a navigation technology for off-board navigation capable of appropriately giving route guide information even in an area where radio communication such as communication by a cellphone is not available.;SOLUTION: In the off-board navigation for requesting route search from an on-vehicle device to a server via radio communication, in addition to original guide route, one or more alternative guide route data are downloaded from the server in advance in case the vehicle goes out of the route in an area where radio communication such as by a cellphone or a PHS is not available. When the vehicle goes out of the route in the uncommunicable area, without communicating with an external server, the guide is changed to an alterative route corresponding to specific guide points. Thereby, the smooth and appropriate guide is made continuable a problem of being lost is prevented, and a sense of security of user can be enhanced.;COPYRIGHT: (C)2003,JPO