| 摘要 |
A client/server navigation system utilizes partial route guidance trees, enabling a thin, mobile client to detect route deviation and provide alternate instructions while awaiting response from a server. The system ( 10 ) consists of a server ( 28 ) containing a network database and route-calculation program; a client ( 26 ) capable of obtaining ( 12 ) its current location and destination, displaying route instructions ( 22 ), and determining when it needs additional instructions from the server ( 20,24 ); and communication ( 30,32,34,36 ) between the client ( 26 ) and server ( 28 ). The invention allows for long routes and responsive operation on a small, low-powered client despite lags and lapses in communication.
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