Power save mechanisms for dynamic ad-hoc networks

• US 8,233,456 B1
• Filed: 10/04/2007
• Issued: 07/31/2012
• Est. Priority Date: 10/16/2006
• Status: Active Grant

• Current Assignee: NXP USA, Inc. (NXP Semiconductors NV)
• Original Assignee: Marvell International Limited (Marvell Technology Group Limited)
• Inventors: Kopikare, Rahul, Kopikare, Milind, Chhabra, Kapil
• Primary Examiner(s): JAIN, RAJ K
• Application Number:
  US11/867,665
• Time in Patent Office: 1,762 Days
• Field of Search: None
• US Class Current: 370/332
• 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 52/0225 using monitoring of external events, e.g. the presence of a signal
• CPC Class Codes: H04W 52/0229 where the received signal is a wanted signal
• CPC Class Codes: H04W 76/10 Connection setup
• 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

Techniques for establishing a dynamic ad-hoc wireless network are disclosed. A node transitions between wake and sleep modes during periods defined as beacon intervals. Before a network connection is established and while it is awake, the node transmits network connection request and also listens for network activity. If a beacon or response message is not detected while the node is listening, the node enters sleep mode and thereby conserves power. The node optionally changes the duration of its detection period and/or the time at which it listens for network activity relative to the start of each beacon interval. Information elements are optionally included with transmitted beacons or response messages.

Claims

1. A method of establishing a wireless ad-hoc network connection, the method comprising:

defining a beacon interval at a first node, said beacon interval having a first subinterval and a second subinterval;

sending a network connection request from said first node during a first portion of said first subinterval;

detecting a network connection request from a second node during a second portion of said first subinterval; and

entering a sleep mode during said second subinterval absent detecting said network connection request from said second node.

2. The method of claim 1 wherein during said sleep mode said first node does not detect or send network connection requests.

3. The method of claim 1 further comprising:

defining a monitoring period spanning an integral number of beacon intervals; and

extending a duration of said first subinterval to one beacon interval following each monitoring period thereby canceling the second subinterval during said one beacon interval following each monitoring period.

4. The method of claim 1 further comprising:

establishing a network connection with said second node upon detecting said network connection request from said second node; and

exchanging data with said second node using said network connection.

5. The method of claim 4 further comprising:

transmitting an acknowledgement message responsive to said network connection request from said second node;

waiting for a reply from said second node to said acknowledgement message; and

terminating said network connection if said reply is not received within a predetermined amount of time.

6. The method of claim 4 further comprising:

suspending said sleep mode for a duration of said network connection.

7. The method of claim 1 further comprising:

detecting an acknowledgment message from said second node responsive to said network connection request of said first node; and

establishing a network connection with said second node.

8. The method of claim 7, further comprising:

sending a reply to said acknowledgement request enabling said network connection with said second node to be established.

9. The method of claim 1 wherein a duration of said second subinterval is at least 90% of the duration of said beacon interval.

10. The method of claim 1, further comprising:

defining a monitoring period, said monitoring period including an integral number of beacon intervals;

wherein, after each monitoring period, a duration of said second portion is changed at said first node from a first value to a second value, and

wherein said second value is determined in relation to said second node to provide detection of a network connection request between said first node and said second node within a predetermined number of beacon intervals.

11. The method of claim 10, wherein said second value corresponds to a duration equal to approximately one-half of said beacon interval.

12. The method of claim 10, wherein said second value corresponds to a duration equal to one-half of said beacon interval and an additional period related to a time required to establish said wireless ad-hoc connection.

13. The method of claim 10, wherein, during said sleep mode, said first node does not detect or send network connection requests.

14. A device adapted to participate in a wireless ad-hoc network, the device comprising:

a controller configured to define a beacon interval of the device, the beacon interval having a first subinterval and a second subinterval;

a transmitter configured to send a network connection request during a first portion of said first subinterval;

a receiver configured to detect a network connection request from a second device during a second portion of said first subinterval; and

wherein said controller causes the device to enter a sleep mode during said second subinterval absent detecting said network connection request from said second device.

15. The device of claim 14 wherein during said sleep mode the device does not detect or send network connection requests.

16. The device of claim 14 wherein said controller is further configured to define a monitoring period spanning an integral number of beacon intervals, and to extend the duration of said first subinterval to one beacon interval following each monitoring period thereby canceling said second subinterval during said one beacon interval following each monitoring period.

17. The device of claim 14 wherein said controller is further configured to establish a network connection with said second device upon detecting said network connection request from said second device and to cause data to be exchanged with said second device using said network connection.

18. The device of claim 17 wherein said controller is further configured to transmit an acknowledgement message responsive to said network connection request from said second device;

said controller is configured to wait for a reply from said second device to said acknowledgement message; and

said controller is configured to terminate said network connection if said reply is not received within a predetermined amount of time.

19. The device of claim 17 wherein said controller is further configured to suspend said sleep mode for a duration of said network connection.

20. The device of claim 14 wherein said controller is further configured to detect an acknowledgment message from said second device responsive to said network connection request sent by the device, and to cause a network connection to be established with said second device.

21. The device of claim 20, wherein said controller is further configured to send a reply to said acknowledgement request enabling a network connection with said second device to be established.

22. The device of claim 14 wherein a duration of said second subinterval is at least 90% of a duration of said beacon interval.

23. The device of claim 14, wherein said controller is further configured to define a monitoring period spanning an integral number of beacon intervals;

wherein, after each monitoring period, said controller changes a duration of said second portion from a first value to a second value, and

wherein said second value is determined in relation to said second device to provide detection of a network connection request between the devices within a predetermined number of beacon intervals.

24. The device of claim 23, wherein said second value corresponds to a duration equal to approximately one-half of said beacon interval.

25. The device of claim 23, wherein said second value corresponds to a duration equal to one-half of said beacon interval and an additional period related to a time required to establish said wireless ad-hoc connection.

26. The device of claim 23, wherein network connection requests are not detected or sent during said sleep mode.