Wireless ad hoc communication system, terminal, processing method in terminal and program to make terminal execute processing method

Abstract

A wireless ad hoc communication system is provided in which in the case where an alternative route can not be discovered in a certain node, a restoration is attempted in an intermediate node instead of deleting all routes up to a transmission source. In order to do so, a route discovery process 20 discovers and sets a route when a corresponding route is not set at the time of data communication request 10. A link state management process 40 monitors a state of a link 30 on the route set by the route discovery process 20, and updates a link state in a route table of each wireless terminal. When the link quality deteriorates, a route information notification process 50 notifies the link state to urge a retention of transmission data. An alternative route search process 60 searches an alternative route when the link quality deteriorates, and traces back to a terminal on the transmission side in order to search further when the alternative route is not discovered. A route switching process 70 switches a possible alternative route as a qualified route.

1 . A first intermediate terminal configured:
 for use in a wireless ad hoc communication system including a plurality of terminals including a source terminal which transmits communication data and a destination terminal which receives the communication data;   to transmit an alternative route discovery request when the quality of a link connected to the first intermediate terminal between the source terminal and the destination terminal deteriorates;   to transmit a route error notification to a second intermediate terminal when the request fails; and   to notify the second intermediate terminal of route information for an alternative route between the second intermediate terminal and the destination terminal when the alternative route becomes useable.   
     
     
         2 . A method implemented in a first intermediate terminal used in an ad hoc wireless communication system including a source terminal which transmits communication data and a destination terminal which receives the communication data, the method comprising the steps of:
 transmitting an alternative route discovery request when the quality of a link connected to the first intermediate terminal between the source terminal and the destination terminal deteriorates;   transmitting a route error notification to a second intermediate terminal when the request fails; and   notifying the second intermediate terminal of route information for an alternative route between the second intermediate terminal and the destination terminal when the alternative route becomes useable.   
     
     
         3 . A second intermediate terminal configured:
 for use in a wireless ad hoc communication system including a plurality of terminals including a source terminal which transmits communication data and a destination terminal which receives the communication data;   to receive from a first intermediate terminal for an alternative link route;   to identify a candidate alternative link route upon receipt of such request;   to reply to the first intermediate terminal with information regarding the candidate alternative link route;   to send the candidate alternative link route to the destination terminal when the reply is received by the first intermediate terminal and transfer the reply to a further terminal;   to receive and process a first command to switch the route from the first intermediate terminal;   to send the candidate alternative link route to the destination terminal as a qualified route when the first command is received and transfer the first command to a further terminal; and   to send the candidate alternative link route to the source terminal as the qualified route when a second command is received from the destination terminal and to transfer the second command to a further terminal, the qualified alternative route linking the second intermediate terminal to the destination terminal.   
     
     
         4 . A method implemented in a second intermediate terminal used in an ad hoc wireless communication system including a source terminal which transmits communication data and a destination terminal which receives the communication data, the method comprising the steps of:
 receiving and processing a request from a first intermediate terminal for an alternative link route;   identifying a candidate alternative link route upon receipt of such request;   replying to the first intermediate terminal with information regarding the candidate alternative link route;   sending the candidate alternative link route to the destination terminal when the reply is received by the first intermediate terminal and transferring the reply to a further terminal;   receiving and processing a first command to switch the route from the first intermediate terminal;   sending the candidate alternative link route to the destination terminal as a qualified route when the first command is received and transferring the first command to a further terminal; and   sending the selection of the candidate alternative link route to the source terminal as the qualified route when a second command is received from the destination terminal and transferring the second command to a further terminal, the qualified alternative route linking the second intermediate terminal to the destination terminal.