Cluster head resignation to improve routing in mobile communication systems

• US 20030041150A1
• Filed: 09/04/2002
• Published: 02/27/2003
• Est. Priority Date: 07/24/2000
• Status: Active Grant

• Current Assignee: Raytheon BBN Technologies Corp. (Rtx Corporation)
• Original Assignee: BBNT Solutions LLC (Rtx Corporation)
• Inventors: Weinstein, Joseph J., Elliott, Brig Barnum, Passman, William S., Zavgren, John R., Manning, Keith W.
• Granted Patent: US 6,662,229 B2
• Time in Patent Office: Days
• US Class Current: 709/227
• CPC Class Codes: H04L 45/04 Interdomain routing, e.g. hierarchical routing
• CPC Class Codes: H04W 84/20 Master-slave selection or change arrangements

Abstract

A communications system for communication among plural stations in a network has stations (CH1, CM2, CM3, CH4, CH5, CM6, CM7) arranged in clusters (1a, 1b, 1c) of communication member stations, each communicating with each other. One of the member stations (CH1, CH4, CH5) is a head station of the cluster. The cluster head stations (CH1, CH4, CH5) communicate with other cluster head stations (CH1, CH4, CH5). A method for configuring the network of stations includes a step of operating at least a first (CH5) and a second (CH4) station of the plural stations as cluster head stations, the first (CH5) and second (CH4) stations forming a communications link. The method also includes a step to resign the first (CH5) station from operating as a cluster head station when a predetermined resignation condition is met. The method also includes a step of maintaining the communication link between the first (CH5) and second (CH4) station as the first station (CH5) transitions from operating as a cluster head station (CH5) to operating as a cluster member station (CM5) of a cluster headed by the second cluster head station (CH4).

Claims

1. A mobile communications station which communicates among a plurality of mobile stations in a network in which stations are arranged in clusters of communication member stations, with one member station in each cluster being a head station for the cluster, each member station communicating with the network through one or more cluster head stations, the cluster head stations communicating with other cluster head stations, the mobile station including a transceiver which transmits signals to and receives signals from mobile stations in the network, said mobile communications station comprising:

a memory having network information stored thereon; and

a processor which (i) operates said mobile station as a cluster head station;

(ii) resigns said mobile station from operating as a cluster head station; and

(iii) maintains affiliation with a cluster head neighbor at least during a period in which said mobile station resigns from operating as a cluster head and commences operating as a cluster member of the cluster head neighbor.

2. A mobile communications station according to claim 1, wherein said processor controls said transceiver to transmit a signal representing an intention of said mobile station to resign as a cluster head station.

3. A mobile communications station according to claim 1, wherein said processor prevents said mobile station from resigning as a cluster head station based on at least one of a resignation command setting indicating that said mobile station should not resign;

a predetermined plan for said mobile station and nearby stations that indicates whether said mobile station will better serve the network if it does not resign;

indications that other, nearby cluster heads are already in the process of resigning; and

an indicator that some or all of the cluster members affiliated with said mobile station have not reaffiliated with other clusters.

4. A mobile communications station according to claim 1, wherein said processor determines whether said mobile station is a network n-connectivity point, and prevents said mobile station from resigning as a cluster head station when said mobile station is an n-connectivity point.

5. A mobile communications station according to claim 4, wherein the n-connectivity point is an articulation point.

6. A mobile communications station according to claim 4, wherein the network information stored in said memory includes network topology information.

7. A mobile communications station according to claim 6, wherein the network topology information comprises at least one of signal strength, organizational affiliation, number and type of affiliated stations, planned station movement over time, planned radio silence, disruptions of communications caused by jammers, self-interference or natural terrain, and battery power remaining.

8. A mobile communications station according to claim 6, wherein a determination is based on analyzing network topology information.

9. A mobile communications station according to claim 4, wherein said processor selects a first neighboring cluster head station to maintain affiliation with while resigning as a cluster head station.

10. A mobile communications station according to claim 9, wherein a selection is made based on at least one of signal strength, organizational affiliation, and number of cluster members affiliated with the cluster head station.

11. A mobile communications station according to claim 9, wherein a section is made based on at least one of highest percentage of transmissions received without disruption, fastest communication link speed, least power required for transmissions, a station that is most compatible with planned movement of said mobile station, an indicator for radio silence in the future, and a direction for pointing a directional antenna so as to avoid jammers or natural interference.

12. A mobile communications station according to claim 9, wherein said processor controls the transceiver to transmit a signal to the selected first cluster head station requesting a status change from a cluster head station to a cluster member station.

13. A mobile communications station according to claim 12, wherein the processor resigns the mobile station from operating as a cluster head station when said mobile communication station receives an acknowledgement from the selected first cluster head station, while said processor maintains a communication link with the first cluster head station.

14. A mobile communications station according to claim 12, wherein said processor selects a second neighbor cluster head station to maintain affiliation with when said mobile station does not receive an acknowledgement from the first neighbor cluster head.

15. A mobile communications station according to claim 1, wherein said processor controls the transceiver to send a signal to each affiliated cluster member station signaling the intended resignation of said mobile station as a cluster head station.

16. A mobile communications station according to claim 1, wherein said processor prevents said mobile station from resigning as a cluster head station when at least one of the affiliated cluster member stations remain affiliated after receiving the signal.

17. A mobile communications station according to claim 1, wherein said processor controls the transceiver to send a signal to each neighbor cluster head station signaling the intended resignation of said mobile station as a cluster head station.

18. A mobile communications station according to claim 17, wherein said processor controls said mobile station to operate as a cluster member station of a cluster headed by the cluster head neighbor when the transceiver transmits the signal.

19. A network communications apparatus comprising:

a memory which stores network information;

a processor which (i) controls said apparatus to operate as a cluster gateway;

(ii) controls said apparatus to resign from operating as a cluster gateway;

(iii) maintains affiliation with a first cluster gateway at least during a period in which said apparatus ends operation as a cluster gateway and commences operation as a cluster member of the first cluster gateway; and

a transceiver which transmits communication messages.

20. In a communications system for communication among plural member stations in a network in which member stations are arranged in clusters of communication member stations with one of the member stations being a cluster head, each member station communicating with the network through at least one affiliated cluster head stations, the cluster head stations communicating with other cluster head stations, a method of operating a communications station comprising the steps of:

operating the communications station as a cluster head station;

resigning the communications station from operating as a cluster head station; and

maintaining affiliation with a first neighbor cluster head station while the communications station transitions from operating as a cluster head station to operating as a member station of a cluster headed by the first neighbor cluster head station.

21. The method according to claim 20, further comprising the step of continuing operation as a cluster head station in accordance with a resignation indicator.

22. The method according to claim 21, wherein the resignation indicator is selectable by at least one of initial configuration, user input, and input from a central control station.

23. The method according to claim 20, further comprising the step of transmitting a signal representing an intention of the communications station to resign as a cluster head station.

24. The method according to claim 23, further comprising the steps of determining whether the communications station is a network n-connectivity point, and preventing the communications station from resigning as a cluster head station when the mobile station is an n-connectivity point.

25. The method according to claim 24, wherein the n-connectivity point is an articulation point.

26. The method according to claim 20, further comprising the step of transmitting a signal to the first neighbor cluster head to announce resignation and to request a status change from a cluster head neighbor to a cluster member station.

27. The method according to claim 26, further comprising the steps of:

resigning the communications station from operating as a cluster head station when the communications station receives an acceptance signal from the first neighbor cluster head station; and

transmitting a signal to at least a second neighbor cluster head station signaling the resignation of said communications station as a cluster head station.

28. Computer executable code stored on a computer readable medium, the code to operate a communications station so as to communicate with a plurality of mobile stations in a network in which stations are arranged in clusters of communication member stations, with one member station being a cluster head station for each cluster, each member station communicating with the network through at least one affiliated cluster head station, the cluster head station communicating with other cluster head stations, said computer executable code comprising:

code to operate the communications station as a cluster head station;

code to resign the communications station from operating as a cluster head station; and

code to maintain affiliation with a first neighbor cluster head station at least during a period in which the communications station resigns as a cluster head station and commences operating as a member station of a cluster headed by the first neighbor cluster head station.

29. In a communications system for communication among plural stations in a network in which stations are arranged in clusters of communication member stations with one of the member stations being a head station of the cluster, the cluster head stations communicating with other cluster head stations, a method for configuring the network of stations includes the steps of:

operating at least a first and a second station of the plural stations as cluster head stations, the first and second stations forming a communications link;

resigning the first station from operating as a cluster head station when a predetermined resignation condition is met; and

maintaining the communication link between the first and second station as the first station transitions from operating as a cluster head station to operating as a cluster member station of a cluster headed by the second cluster head station.

30. The method according to claim 29, wherein the predetermined resignation condition is a proximity condition with respect to the second station.

31. The method according to claim 29, wherein the predetermined resignation condition is at least one of an expiration of a predetermined time, a number of cluster heads in the network, a location of a cluster head in a network, planned movements of a station, battery power remaining, proximity to jammers, self-interference and natural interference.

32. The method according to claim 29, further comprising the step of transmitting a signal representing an intention of the first station to resign as a cluster head station.

33. The method according to claim 32, further comprising the steps of:

determining whether the first station is a network n-connectivity point, and

preventing the first station from resigning as a cluster head station when the first station is a network n-connectivity point.

34. The method according to claim 33, further comprising the step of transmitting a signal from the first station to the second station to announce resignation and to request a status change from a cluster head neighbor to a cluster member station.

35. The method according to claim 34, further comprising the steps of:

resigning the first station from operating as a cluster head station when the first station receives an acceptance signal from the second station; and

transmitting a signal to at least a third cluster head station of the plural station to signal the resignation of the first station as a cluster head station.

36. A network communications apparatus comprising:

storage means for storing network information;

first control means for controlling an operation of said apparatus in a cluster gateway mode;

second control means for controlling said apparatus to resign from operation in the cluster gateway mode;

maintaining means for maintaining a communications link with a first cluster gateway while the apparatus transitions from operating in the cluster gateway mode to operating in a cluster member mode as a cluster member of a cluster headed by the first cluster head station; and

transmitting means for transmitting communication messages.