Communications apparatus, communications system, and communication method

Abstract

In a network made up of a plurality of devices each capable of a multi-hop communication that conforms to at least one of the wired communication standards or wireless communication standards, each device monitors a communication situation on communication links and path established between the device and a destination device. When the communication situation changes, the device switches the communication path for use in a communication with the destination device to another communication path which can be established between the device and destination device.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating an exemplary configuration of a network in which wired links are mixed with wireless links;

FIG. 2 is a block diagram illustrating an exemplary configuration of an end device and a link device shown in FIG. 1;

FIG. 3 is a state transition diagram representing operation states of the end device and link device shown in FIG. 1;

FIG. 4 is a schematic diagram illustrating how the devices shown in FIG. 1 are connected after links have been established;

FIG. 5 is a table showing an exemplary link database shown in FIG. 2;

FIG. 6 is a table showing an exemplary device database shown in FIG. 2;

FIG. 7 is a flow chart illustrating a processing procedure performed by each of the end devices and link devices shown in FIG. 1;

FIG. 8 is a flow chart illustrating a procedure of a link search process shown in FIG. 7;

FIG. 9 is a flow chart illustrating a procedure of an information exchange process shown in FIG. 7;

FIG. 10 is a flow chart illustrating a procedure of a communication path building process and a procedure of safeguarding the built communication paths within a path management process shown in FIG. 7;

FIG. 11 is a flow chart illustrating a procedure of a communication path switching process within the path management process shown in FIG. 7;

FIG. 12 is a table showing an exemplary device database contained in each of the link devices and end devices in a second embodiment;

FIG. 13 is a schematic diagram illustrating the network configuration in a first example of a communications system according to the present invention;

FIG. 14 is a table showing an exemplary link database built by an end device which has been added to the network illustrated in FIG. 13;

FIG. 15 is a table showing an exemplary device database immediately after communication is started by an end device which has been added to the network illustrated in FIG. 13;

FIG. 16 is a sequence diagram illustrating the operation of the respective devices shown in FIG. 13;

FIG. 17 is a schematic diagram illustrating the network configuration in a second example of the communications system according to the present invention;

FIG. 18 includes tables showing exemplary link databases built by the end devices and link devices after switching to a second communication path shown in FIG. 17;

FIG. 19 is a table showing an exemplary device database built by the end devices and link devices shown in FIG. 17;

FIG. 20 is a sequence diagram illustrating the operation of the respective devices in the second example of the communications system according to the present invention;

FIG. 21 is a schematic diagram illustrating the network configuration in a third example of the communications system according to the present invention;

FIG. 22 is a table showing an exemplary link database which is built by a link device added to the network illustrated in FIG. 21 after a link has been found;

FIG. 23 is a table showing an exemplary device database which has been built before a link device is added to the network illustrated in FIG. 21;

FIG. 24 is a sequence diagram illustrating the operation of the respective devices in the third example of the communications system according to the present invention;

FIG. 25 is a schematic diagram illustrating the network configuration in a fourth example of the communications system according to the present invention;

FIG. 26 is a table showing an exemplary device database before a reservation of first traffic, after the reservation of the first traffic, and after a reservation of second traffic; and

FIG. 27 is a sequence diagram illustrating the operation of the respective devices shown in FIG. 25.

Claims

1. A communications apparatus for use in a communications system which has a network made up of a plurality of devices each capable of a multi-hop communication conforming to at least one wired communication standards or wireless communication standards, said communications apparatus comprising: a control processing unit for monitoring a communication situation on communication links and path established between said communication apparatus and a destination communications apparatus, and responsive to a change in the communication situation for switching the communication path for use in a communication with the destination communications apparatus to another communication path which can be established between said communications apparatus and said destination communications apparatus.

2. The communications apparatus according to claim 1, wherein: said change in the communication situation is new traffic generated on a communication path established between said communications apparatus and said destination communications apparatus.

3. The communications apparatus according to claim 1, wherein: said change in the communication situation is degraded of the communication environment.

4. The communications apparatus according to claim 1, wherein: said change in the communication situation is amelioration of the communication environment.

5. The communications apparatus according to claim 1, further comprising: a link database for storing link information required to establish a link between said communications apparatus and another communications apparatus on said network; anda device database for storing device information on each communications device on said network, classified according to available communication standards.

6. A communications system having a network which is built using a plurality of the communications apparatuses according to claim 1.

7. A method of communicating between devices in a network made up of a plurality of said devices, each capable of a multi-hop communication conforming to at least one wired communication standards or wireless communication standards, wherein: said device monitors a communication situation on communication links and path established between said device and a destination device; andwhen the communication situation changes, said device switches the communication path for use in a communication with the destination device to another communication path which can be established between said device and said destination device.

8. The communication method according to claim 7, wherein: said change in the communication situation is new traffic generated on a communication path established between said device and said destination.

9. The communication method according to claim 7, wherein: said change in the communication situation is a degradation of the communication environment.

10. The communication method according to claim 7, wherein: said change in the communication situation is amelioration of the communication environment.