Distributed beaconing periods for ad-hoc networks

• US 9,655,139 B2
• Filed: 03/21/2005
• Issued: 05/16/2017
• Est. Priority Date: 03/24/2004
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips N.V.
• Inventors: Habetha, Joerg, del Prado Pavon, Javier
• Primary Examiner(s): MAPA, MICHAEL Y
• Application Number:
  US10/599,160
• Publication Number:
  US 20070274206A1
• Time in Patent Office: 4,439 Days
• Field of Search: 370321-324, 370329-330, 370337-338, 370341, 370347-348, 370350, 370442-445, 370462, 455 412, 4554261, 455450-455, 455509-516
• CPC Class Codes: H04W 74/006 in the downlink, i.e. towards the terminal
• CPC Class Codes: H04W 74/0891 for synchronized access
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

In a distributed Mac protocol having a slotted superframe (102) comprising at least one slotted beacon period (104) followed by a data transfer period (103), a system and method is provided for creating and maintaining several beacon periods (104) at different positions in the superframe (102). When joining the network (300) a device (301) either joins an existing beacon period (104) or creates a new beacon period (104) at a position in the superframe (102) that does not overlap with existing beacon periods (104) or reservation periods. Beacon periods (104) mutually protect each other by devices (301) announcing the neighboring beacon periods in their beacons.

Claims

1. A method for a distributed beaconing period protocol for a device in an ad hoc network of devices, the method comprising:

dividing a medium access time into a sequence of at least one contiguous superframe beginning at a Beacon Period Start Time;

partitioning the superframe into a slotted Beaconing Period (BP), having a plurality of contiguous beacon slots, followed by a data transfer period;

associating with at least one of an existing ad hoc network BP or creating a new ad hoc network BP as the BP of the device, wherein the device stores an occupancy of the beacon slots and its own beacon slot number of the Beaconing Period, wherein

when the BP of the device is not protected in at least one neighboring BP, protecting the BP by including a first reservation for the BP in the beacon of the device in the at least one neighboring BP, and

when the BP of the device is protected, operating normally by receiving beacons over the medium; and

when a beacon comprising a Distributed Reservation Protocol (DRP) reservation of type BP is received, scanning for a new BP, and when a new BP is detected, protecting the new BP.

2. The method of claim 1, wherein the first reservation is a Distributed Reservation Protocol (DRP) reservation of type BP and priority =BP.

3. The method of claim 1, wherein the associating further comprises:

choosing an empty slot of the BP of the device; and

beaconing a beacon of the device in the chosen empty slot.

4. The method of claim 3, further comprising including information regarding beacons of other devices in the beacon of the device.

5. The method of claim 4, wherein the protecting the unprotected BP further comprises including a second reservation in the beacon of the device to announce the BP of said other devices.

6. The method of claim 5, wherein the second reservation is a Distributed Reservation Protocol (DRP) reservation of type BP and priority =BP.

7. The method of claim 1, wherein the associating comprises:

scanning the medium to detect at least one BP during the at least one superframe;

when at least one BP is not detected, starting the new ad hoc network BP as the BP of the device at a beacon period start time calculated in a pre-determined manner; and

when at least one BP is detected;

joining at least one of the at least one detected BP as the BPs of the device, or starting the new ad hoc network BP as the BP of the device at a beacon period start time determined in a pre-determined manner.

8. The method of claim 7, wherein the associating further comprises:

choosing an empty slot of the BP of the device and

beaconing a beacon of the device in the chosen empty slot.

9. The method of claim 8, further comprising including information regarding beacons of other devices in the beacon of the device.

10. The method of claim 6, wherein the protecting further comprises including a third reservation in the beacon of the device in the neighboring BPs to announce the BP.

11. The method of claim 1, wherein the third reservation is a Distributed Reservation Protocol (DRP) reservation of type BP and priority =BP.

12. The method of claim 1, wherein the protecting further comprises including a fourth reservation in the beacon of the device to protect the BP.

13. The method of claim 12, wherein the fourth reservation is a DRP reservation of type BP and priority =BP.

14. The method of claim 1, wherein the operating normally further comprises a device optionally switching BP, when two or more BPs co-exist.

15. The method of claim 14, wherein the switching BP by the device further comprises:

including a special switching announcement field in a beacon to announce a new BP; and

beaconing for at least a predetermined announcement number of consecutive superframes with the beacon including the special switching announcement field.

16. The method of claim 15, wherein the beaconing further comprises:

including a DRP reservation of type BP to protect the new BP, when the new BP is not already protected, stopping transmission of the beacon, when the new BP is already protected; and

transmitting a beacon in the new BP.

17. The method of claim 15, wherein the operating normally further comprises:

when a beacon comprising a BP switching announcement of another device is received,

scanning for a new BP, and

when a new BP is detected, protecting the new BP.

18. The method of claim 1, wherein the operating normally further comprises terminating the BP.

19. The method of claim 1, wherein the operating normally further comprises clearing a Distributed Reservation Protocol (DRP) BP reservation of the device when no beacons are received during the BP for a pre-determined clearing number of consecutive superframes.

20. The method of claim 1, wherein the operating normally further comprises when at least two BPs collide, until there are no longer any colliding BPs, repeatedly performing:

searching each colliding BP for enough empty beacon slots for devices of another colliding BP, and

moving at least one colliding BP to a non-colliding beacon period start time;

or

searching the superframe for enough empty beacon slots for the BP, and

moving the BP to the empty slots in the superframe.

21. The method of claim 20, wherein the operating normally further comprises when an existing DRP reservation collides with a BP, moving a colliding DRP reservation to a non-colliding time.

22. The method of claim 20, wherein the operating normally further comprises moving the BP to a non-colliding time when an existing DRP reservation collides with a BP.

23. The method of claim 1, further comprising each device of the network of devices beaconing in the same BP, by performing a selected one from the group consisting of:

beaconing in parallel in each BP of each device of said network of devices; and

switching a BP to beacon in a same BP as other devices of said network of devices.

24. The method of claim 23, wherein a device that does not have to switch the BP is chosen in a distributed way based on an identifier of each device of said network of devices.

25. The method of claim 23, wherein a device that does not have to switch the BP is chosen in a distributed way based on a number of occupied beacon slots in the BP of each device of said network of devices.

26. The method of claim 23, wherein a device that does not have to switch the BP is chosen in a distributed way based on a size of a portion of the superframe that is reserved by the beacons in a BP of a device of said network of devices.

27. The method of claim 1, wherein each device of said network of devices may beacon in a different BP.