POWER MANAGEMENT IN A WIRELESS AD HOC NETWORK

• US 20120170468A1
• Filed: 12/29/2010
• Published: 07/05/2012
• Est. Priority Date: 12/29/2010
• Status: Active Grant

• Current Assignee: General Dynamics C4 Systems Incorporated (General Dynamics Corporation)
• Original Assignee: General Dynamics C4 Systems Incorporated (General Dynamics Corporation)
• Inventors: La Macchia, Michael P., Wormley, Mark L., Palermo, Keith
• Granted Patent: US 8,582,540 B2
• Time in Patent Office: Days
• US Class Current: 370/252
• CPC Class Codes: H04L 47/24 Traffic characterised by specific attributes, e.g. priority or QoS
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 28/0284 detecting congestion or overload during communication monitoring arrangements H04L43/00
• CPC Class Codes: H04W 28/0289 Congestion control load shedding arrangements in network planning H04W16/08; performing reselection for handling the traffic H04W36/22; wireless traffic scheduling H04W72/12
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0219 where the power saving management affects multiple terminals
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

In a wireless ad hoc network (20) of nodes (22), a method (64) of power management entails monitoring (82) a current traffic load of the network (20), and in response to the current traffic load, selecting (106, 132) a subset (102) of epochs (80) within cyclically repeating time windows (78) for network communication. A message (122) is communicated (120) between the nodes (22) in the network (20). The message (122) identifies the subset (102) of epochs (80) for using in communicating network traffic (32). Following receipt of the message, each of the nodes (22) modifies (124) a transmit capability mode by entering a run state (40) during the epochs (80) within the subset (102) to enable communication of network traffic (32) and by entering a low power consumption idle state (42) during the remaining epochs (80) within the time window (78).

Claims

1. A method of power management in a wireless ad hoc network, said network including a plurality of nodes, and said method comprising:

monitoring a current traffic load of said wireless ad hoc network;

in response to said current traffic load, selecting a subset of epochs within a time window of epochs for network communication;

communicating a message between said nodes in said network, said message identifying said subset of epochs as being allowable for use in communicating network traffic; and

following receipt of said message, said each of said nodes modifying a transmit capability mode by entering a run state to enable communication of said network traffic over said network during said epochs within said subset of epochs and by entering an idle state during remaining ones of said epochs within said time window.

2. A method as claimed in claim 1 wherein said time window is one of cyclically repeated time windows, each of said cyclically repeated time windows comprising said epochs, and said method further comprises:

communicating said network traffic during said epochs within said subset of epochs for said each of said cyclically repeated time windows; and

abstaining from communicating said network traffic during said each of said cyclically repeated time windows when said each of said nodes is in said idle state.

3. A method as claimed in claim 1 wherein said current traffic load is a first traffic load determined at a first instant in time, said subset of epochs is a first subset of epochs, and said method further comprises:

detecting a second current traffic load at a second instant in time following said first instant in time;

adjusting said first subset of epochs to form a second subset of epochs within said time window in response to said second current traffic load;

communicating a second message between said nodes in said network, said second message identifying said second subset of epochs as being allowable for use in communicating said network traffic; and

following receipt of said second message, said each of said nodes modifying said transmit capability mode by entering said run state to enable communication of said network traffic during said epochs within said second subset of epochs and by entering said idle state during said remaining ones of said epochs within said time window.

4. A method as claimed in claim 3 further comprising

comparing said second current traffic load with one of a high traffic load threshold and a low traffic load threshold;

said adjusting operation increases a second quantity of said epochs within said second subset of epochs relative to a first quantity of said epochs within said first subset of epochs when said second current traffic load is greater than said high traffic load threshold; and

said adjusting operation decreases said second quantity of said epochs within said second subset of epochs relative to said first quantity of said epochs within said first subset of epochs when said second current traffic load is less than said low traffic load threshold.

5. A method as claimed in claim 4 further comprising:

detecting a mobility characteristic for said each of said nodes, said mobility characteristic being one of a substantially static characteristic and a mobile characteristic;

said adjusting operation increases said second quantity of said epochs within said second subset of epochs when said second current traffic load is greater than said high traffic load threshold and said mobility characteristic for at least some of said nodes is said mobile characteristic; and

said adjusting operation decreases said second quantity of said epochs within said second subset of epochs when said second current traffic load is less than said low traffic load threshold and said mobility characteristic for said at least some of said nodes is said substantially static characteristic.

6. A method as claimed in claim 3 wherein:

said adjusting operation increases a second quantity of said epochs of within said second subset of epochs relative to a first quantity of said epochs within said first subset of epochs; and

said modifying operation modifies said transmit capability mode in accordance with an aggressive recovery policy, said aggressive recovery policy enabling said network communication during said second subset of epochs in accordance with a rapid increase characteristic of said aggressive recovery policy.

7. A method as claimed in claim 3 wherein:

said adjusting operation decreases a second quantity of said epochs within said second subset of epochs relative to a first quantity of said epochs within said first subset of epochs; and

said modifying operation modifies said transmit capability mode in accordance with a gradual decay policy, said gradual decay policy enabling said network communication within said second subset of epochs in accordance with a gradual decrease characteristic of said gradual decay policy.

8. A method as claimed in claim 1 wherein said subset of epochs is a first subset of epochs, and said method further comprises:

determining a priority characteristic of said network traffic;

adjusting said first subset of epochs to form a second subset of epochs within said time window in response to said priority characteristic;

communicating a second message between said nodes in said network, said second message identifying said second subset of epochs as being allowable for use in transmitting said network traffic; and

following receipt of said second message, each of said nodes modifying said transmit capability mode by enabling communication of said network traffic during said second subset of epochs and entering said idle state during said remaining ones of said epochs.

9. A method as claimed in claim 8 wherein:

when said priority characteristic of said network traffic is greater than a high priority threshold, increasing a second quantity of said epochs within said second subset of epochs relative to a first quantity of said epochs within said first subset of epochs for communication of said network traffic; and

when said priority characteristic of said network traffic is less than a low priority threshold, decreasing said second quantity of said epochs within said second subset of epochs relative to said first quantity of said epochs within said first subset of epochs for communication of said network traffic.

10. A method as claimed in claim 8 wherein said priority characteristic is a latency characteristic of said network traffic, and said method further comprises:

determining that said latency characteristic calls for minimal latency in transmission of said network traffic; and

increasing a second quantity of said epochs in said second subset of epochs relative to a first quantity of said epochs within said first subset of epochs for communication of said network traffic.

11. A method as claimed in claim 1 wherein said selecting operations comprises selecting at least two of said epochs within said time window for inclusion in said subset of epochs, said at least two of said epochs being immediately adjacent one another within said time window of said epochs.

12. A method as claimed in claim 1 wherein said selecting operations comprises selecting at least two of said epochs within said time window for inclusion in said subset of epochs, said at least two of said epochs being approximately uniformly distributed within said time window of said epochs.

13. A method as claimed in claim 1 wherein said one of said nodes is a network manager, and said monitoring, selecting and communicating operations are performed by said network manager.

14. A method as claimed in claim 1 wherein said monitoring and selecting operations are performed by said each of said nodes, and said communicating operation comprises:

communicating a plurality of management messages between said nodes, said plurality of management messages including nodal traffic loads; and

said selecting operation comprises collectively selecting said subset of epochs for communication of said network traffic in response to said nodal traffic load, said collectively selecting being performed by common consent between said nodes within said ad hoc network.

15. A wireless ad hoc network comprising:

a plurality of wireless nodes configured for network communication, each of said wireless nodes being capable of functioning in either of an operational mode and a sleep mode, wherein said operational mode includes a run state and an idle state, said each wireless node consuming less power in said idle state than in said run state;

a processor for managing power consumption of said nodes in said wireless ad hoc network; and

a computer-readable storage medium containing executable code for instructing said processor to perform operations comprising;

monitoring a current traffic load of said wireless ad hoc network;

in response to said current traffic load, selecting a subset of epochs within a time window of epochs for network communication;

communicating a message between said nodes in said network, said message identifying said subset of epochs as being allowable for use in communicating network traffic, wherein following receipt of said message, said each of said nodes modifies its transmit capability mode by entering said run state to enable communication of said network traffic over said network during said epochs within said subset of epochs and by entering said idle state during remaining ones of said epochs within said time window.

16. A wireless ad hoc network as claimed in claim 15 wherein said current traffic load is a first traffic load determined at a first instant in time, said subset of epochs is a first subset of epochs, and said executable code instructs said processor to perform further operations comprising:

detecting a second current traffic load at a second instant in time following said first instant in time;

adjusting said first subset of epochs to form a second subset of epochs within said time window in response to said second current traffic load;

communicating a second message between said nodes in said network, said second message identifying said second subset of epochs as being allowable for use in communicating said network traffic; and

following receipt of said second message, said each of said nodes modifying said transmit capability mode by entering said run state to enable communication of said network traffic during said epochs within said second subset of epochs and by entering said idle state during said remaining ones of said epochs within said time window.

17. A wireless ad hoc network as claimed in claim 15 wherein said processor and said executable code are incorporated in each of said nodes, and said executable code instructs said processor at said each node to perform further operations comprising:

communicating a plurality of management messages between said nodes, said plurality of management messages including nodal traffic loads; and

said selecting operation comprises collectively selecting said subset of nodes for communication of said network traffic in response to said nodal traffic load, said collectively selecting being performed by common consent between said nodes within said wireless ad hoc network.

18. A method of power management in a wireless ad hoc network, said network including a plurality of nodes, and said method comprising:

monitoring a first traffic load of said wireless ad hoc network at a first instant in time;

in response to said first traffic load, selecting a first subset of epochs within a time window of epochs for network communication;

communicating a message between said nodes in said network, said message identifying said first subset of epochs as being allowable for use in communicating network traffic;

following receipt of said message, said each of said nodes modifying a transmit capability mode by entering a run state to enable communication of said network traffic over said network during said epochs within said first subset of epochs and by entering an idle state during remaining ones of said epochs within said time window;

detecting a second traffic load and a priority characteristic of said network traffic at a second instant in time following said first instant in time;

adjusting said first subset of epochs to form a second subset of epochs within said time window in response to said second current traffic load and said priority characteristic;

communicating a second message between said nodes in said network, said second message identifying said second subset of epochs as being allowable for use in communicating said network traffic; and

following receipt of said second message, said each of said nodes modifying said transmit capability mode by entering said run state to enable communication of said network traffic during said epochs within said second subset of epochs and by entering said idle state during said remaining ones of said epochs within said time window.

19. A method as claimed in claim 18 further comprising

comparing said second current traffic load with one of a high traffic load threshold and a low traffic load threshold;

said adjusting operation increases a second quantity of said epochs within said second subset of epochs relative to a first quantity of said epochs within said first subset of epochs when said second current traffic load is greater than said high traffic load threshold; and

said adjusting operation decreases said second quantity of said epochs within said second subset of epochs relative to said first quantity of said epochs within said first subset of epochs when said second current traffic load is less than said low traffic load threshold.

20. A method as claimed in claim 18 wherein said priority characteristic is a latency characteristic of said network traffic, and said method further comprises:

determining that said latency characteristic calls for minimal latency in transmission of said network traffic; and

increasing a second quantity of said epochs in said second subset of epochs relative to a first quantity of said epochs within said first subset of epochs for communication of said network traffic.