TDMA CHANNEL ACCESS SCHEDULING WITH NEIGHBOR INDIRECT ACKNOWLEDGMENT ALGORITHM (NbIA) FOR AD-HOC NETWORKS

• US 20080008138A1
• Filed: 07/06/2006
• Published: 01/10/2008
• Est. Priority Date: 07/06/2006
• Status: Active Grant

• Current Assignee: Stingray IP Solutions LLC (Acacia Research Corporation)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: PUN, Ngan-Cheung
• Granted Patent: US 7,768,992 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04W 74/0841 with collision treatment
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A mobile ad-hoc network (MANET) includes a source mobile node, a destination mobile node, and a plurality of neighboring mobile nodes. The mobile nodes are operative for contending for a plurality of time division multiple access (TDMA) slots in a frame using beacons. Each neighboring node selects a TDMA slot per frame. For neighboring nodes not receiving an acknowledgment for successful beacons, those nodes contend on empty TDMA slots and resolve residual collisions using a collision detection mechanism.

Claims

1. A method for operating a mobile ad-hoc network (MANET) comprising a plurality of mobile nodes and a plurality of wireless communications links connecting the mobile nodes together, which comprises:

contending for a plurality of Time Divisions Multiple Access (TDMA) slots in a frame using beacons from mobile nodes that are neighboring an n-hop distance to a source mobile node;

each neighboring node selecting a TDMA slot per frame;

for neighboring nodes not receiving an acknowledgement for successful beacons, contending on empty TDMA slots; and

resolving residual collisions using a collision detection mechanism.

2. The method according to claim 1, wherein said neighboring nodes are positioned within a two-hop distance.

3. The method according to claim 1, wherein each node continues on a TDMA slot for a plurality of frames.

4. The method according to claim 1, wherein the step of resolving residual collisions comprises using a void of bits within a Beacon Occupancy Vector (BOV).

5. The method according to claim 1, wherein the step of resolving residual collisions comprises using a message exchange mechanism with a selected neighboring node by temporarily swapping a beacon transmission time with an arbitrarily selected neighboring node to detect beacon collisions.

6. The method according to claim 1, which further comprises embedding an acknowledgement message into a beacon by selecting most recently heard beacons that are referenced to a transmission time within a single frame.

7. The method according to claim 1, which further comprises receiving an acknowledgement of a beacon and maintaining a transmit schedule.

8. The method according to claim 1, which further comprises propagating a timing reference throughout the network for synchronizing a plurality of mobile nodes.

9. The method according to claim 8, which further comprises determining a timing reference by synchronizing with a mobile node that has a global positioning sensor (GPS) or synchronizing with a mobile node that is selected to represent a network timing reference.

10. The method according to claim 8, which further comprises adopting within a mobile node a received timing reference from a packet when the mobile node has not synchronized its internal timing to an external timing reference.

11. The method according to claim 8, which further comprises synchronizing within a node to a timing reference that has been received and has a higher preference than the timing reference that the node has already been synchronized.

12. A method for operating a mobile ad-hoc network (MANET) comprising a plurality of mobile nodes and a plurality of wireless communications links connecting the mobile nodes together, which comprises:

contending for a plurality of Time Division Multiple Access (TDMA) slots in a frame using beacons from mobile nodes that are neighboring an n-hop distance to a source mobile node;

each neighboring node selecting a TDMA slot per frame;

for neighboring nodes not receiving an acknowledgement for successful beacons, contending on empty TDMA slots; and

resolving residual collisions using a void of bits within a Beacon Occupancy Vector (BOV) and a two-level BOV to distribute TDMA slot occupancy information to neighboring nodes and compensating for topology change due to node movement.

13. The method according to claim 12, wherein said neighboring nodes are positioned within a two-hop distance.

14. The method according to claim 12, wherein each node continues on a TDMA slot for a plurality of frames.

15. The method according to claim 12, which further comprises embedding an acknowledgement message into beacon slot contentions for reducing beacon bandwidth requirements.

16. The method according to claim 12, which further comprises receiving an acknowledgement of a beacon and maintaining a transmit schedule.

17. The method according to claim 12, which further comprises propagating a timing reference throughout the network for synchronizing a plurality of mobile nodes.

18. The method according to claim 17, which further comprises determining a timing reference by synchronizing with a mobile node that has a global positioning sensor (GPS) or synchronizing with a mobile node that is selected to represent a network timing reference.

19. The method according to claim 17, which further comprises adopting within a mobile node a received timing reference from a packet when the mobile node has not synchronized its internal timing to an external timing reference.

20. The method according to claim 17, which further comprises synchronizing within a node to a timing reference that has been received and has a higher preference than the timing reference that the mobile node has already been synchronized.

21. A mobile ad-hoc network (MANET) comprising:

a source mobile node;

a destination mobile node; and

a plurality of neighboring mobile nodes, wherein said neighboring mobile nodes are operative for contending for a plurality of Time Divisions Multiple Access (TDMA) slots in a frame using beacons, each neighboring node selecting a TDMA slot per frame, wherein for neighboring nodes not receiving an acknowledgement for successful beacons, contending on empty TDMA slots and resolving residual collisions using a collision detection mechanism.

22. The MANET according to claim 21, wherein each mobile node comprises a communications device to communicate wirelessly with other mobile nodes, and a controller to route communications via the communications device.

23. The MANET according to claim 21, wherein said mobile nodes are operative for using a message exchange mechanism wherein neighboring mobile nodes temporarily swap a beacon transmission time to detect beacon collisions.

24. The MANET according to claim 21, and further comprising a timing reference that is propagated throughout the network for synchronizing a plurality of mobile nodes.

25. The MANET according to claim 21, and further comprising a mobile node having a global positioning sensor (GPS) to which other mobile nodes are synchronized.

26. The MANET according to claim 21 and further comprising a mobile node that is operative as a network timing reference.