ARQ MAC FOR AD-HOC COMMUNICATION NETWORKS AND A METHOD FOR USING THE SAME

• US 20030227935A1
• Filed: 02/28/2003
• Published: 12/11/2003
• Est. Priority Date: 06/05/2002
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: MeshNetworks, Inc. (Motorola Solutions, Inc.)
• Inventors: Alapuranen, Pertti O.
• Granted Patent: US 6,687,259 B2
• Time in Patent Office: Days
• US Class Current: 370/437
• CPC Class Codes: H04L 1/0023 characterised by the signalling
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 28/18 Negotiating wireless communication parameters
• CPC Class Codes: H04W 74/00 Wireless channel access
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A system and method for a media access control (MAC) algorithm with separate operation modes for good channel and bad channel communication. Variables, including channel vector values transmitted in request-to-send/clear-to-send (RTS/CTS) messages, are varied depending on channel mode, resulting in optimized system throughput. In a first mode, the present invention provides a system and method to estimate a channel vector length, and communicate the length to a first node and any associated groups of nodes receiving the RTS/CTS sequence. In a second mode, a maximum channel vector length is used, as retransmissions are less probable in good channels.

Claims

1. A method for establishing channel vector length in communications between nodes in an ad-hoc communications network, said network including a plurality of nodes being adapted to transmit and receive signals to and from other nodes in said network, the method comprising:

estimating a channel vector length of a message being communicated via a first data channel;

communicating said estimated channel vector length to at least one node of said plurality;

controlling said at least one node to communicate said estimated channel vector length to a first group of nodes of said plurality;

controlling said at least one node to monitor said data channel and calculate an actual channel vector length based on said monitored data channel; and

controlling said at least one node to communicate said actual channel vector length to said first group of nodes of said plurality.

2. A method as claimed in claim 1, wherein:

said communication of said estimated channel vector length is a first mode of operation for said data channel, wherein said communication via said data channel is subject to a substantial number of retransmissions.

3. A method as claimed in claim 1, wherein said estimating said channel vector length comprises:

controlling a node to estimate said channel vector length based on an expected number of transmitted segments and an expected number of retransmitted segments for said communication.

4. A method as claimed in claim 1, wherein said communicating said estimated channel vector length comprises:

controlling said at least one node to communicate said estimated channel vector length to said at least one node as part of a request to send (RTS) message.

5. A method as claimed in claim 1, wherein said communicating said estimated channel vector length comprises:

controlling said at least one node to communicate said estimated channel vector length to said first group of nodes as part of a clear to send (CTS) message.

6. A method as claimed in claim 1, wherein said monitoring said data channel comprises:

controlling said at least one node to monitor said data channel to detect at least one of a partial segment acknowledgement (ACK) message and an all segments good acknowledgement (ACK) message.

7. A method as claimed in claim 6, wherein said calculating said actual channel vector length comprises:

controlling said at least one node to calculate an actual channel vector length based on said detected at least one of a partial segment acknowledgement (ACK) message and an all segments good acknowledgement (ACK) message.

8. A method as claimed in claim 1, wherein said communicating said actual channel vector length comprises:

controlling said at least one node to communicate said actual channel vector length to said first group of nodes of said plurality as part of a request to send (RTS) message.

9. A method as claimed in claim 1, further comprising:

controlling said at least one node to calculate a checksum for a first node of said plurality; and

communicating said checksum to a second node of said plurality as part of a request to send (RTS) message.

10. A method as claimed in claim 9, further comprising:

controlling said second node to update a channel vector database at said second node based on said RTS message.

11. A method as claimed in claim 1, further comprising:

controlling said at least one node to communicate a maximum channel vector length to said first group of nodes as part of at least one of a clear to send (CTS) and request to send (RTS) message.

12. A method as claimed in claim 11, wherein:

said communication of said maximum channel vector length is a second mode of operation for said data channel, wherein said communication via said data channel is subject to a minimal number of retransmissions.

13. A system for establishing channel vector length in communications between nodes in an ad-hoc communications network, said network including a plurality of nodes being adapted to transmit and receive signals to and from other nodes in said network, the system comprising:

a first node, adapted to estimate a channel vector length of a message being communicated via a first data channel, and to communicate said estimated channel vector length to at least one node of said plurality;

said at least one node, adapted to communicate said estimated channel vector length to a first group of nodes of said plurality;

said at least one node being further adapted to monitor said data channel and to calculate an actual channel vector length based on said monitored data channel; and

said at least one node being further adapted to communicate said actual channel vector length to said first group of nodes of said plurality.

14. A system as claimed in claim 13, wherein:

said communication of said estimated channel vector length is a first mode of operation for said data channel, wherein said communication via said data channel is subject to a substantial number of retransmissions.

15. A system as claimed in claim 13, wherein:

said first node is adapted to estimate said channel vector length based on an expected number of transmitted segments and an expected number of retransmitted segments for said communication.

16. A system as claimed in claim 13, wherein:

said first node is adapted to communicate said estimated channel vector length to said at least one node as part of a request to send (RTS) message.

17. A system as claimed in claim 13, wherein:

said at least one node is adapted to communicate said estimated channel vector length to said first group of nodes as part of a clear to send (CTS) message.

18. A system as claimed in claim 13, wherein:

said at least one node is adapted to monitor said data channel to detect at least one of a partial segment acknowledgement (ACK) message and an all segments good acknowledgement (ACK) message.

19. A system as claimed in claim 18, wherein:

said at least one node is adapted to calculate an actual channel vector length based on said detected at least one of a partial segment acknowledgement (ACK) message and an all segments good acknowledgement (ACK) message.

20. A system as claimed in claim 13, wherein:

said at least one node is adapted to communicate said actual channel vector length to said first group of nodes of said plurality as part of a request to send (RTS) message.

21. A system as claimed in claim 13, wherein:

said at least one node is adapted to calculate a checksum for said first node of said plurality and communicate said checksum to a second node of said plurality as part of a request to send (RTS) message.

22. A system as claimed in claim 21, wherein:

said second node is adapted to update a channel vector database at said second node based on said RTS message.

23. A system as claimed in claim 13, wherein:

said at least one node is adapted to communicate a maximum channel vector length to said first group of nodes as part of at least one of a clear to send (CTS) and request to send (RTS) message.

24. A system as claimed in claim 23, wherein:

said communication of said maximum channel vector length is a second mode of operation for said data channel, wherein said communication via said data channel is subject to a minimal number of retransmissions.

25. A computer-readable medium of instructions, adapted to establish channel vector length in communications between nodes in an ad-hoc communications network, said network including a plurality of nodes being adapted to transmit and receive signals to and from other nodes in said network, comprising:

a first set of instructions, adapted to estimate a channel vector length of a message being communicated via a first data channel, and to communicate said estimated channel vector length to at least one node of said plurality;

a second set of instructions, adapted to control said at least one node to communicate said estimated channel vector length to a first group of nodes of said plurality;

a third set of instructions, adapted to control said at least one node to monitor said data channel and to calculate an actual channel vector length based on said monitored data channel; and

a fourth set of instructions, adapted to control said at least one node to communicate said actual channel vector length to said first group of nodes of said plurality.

26. A computer-readable medium of instructions as claimed in claim 25, wherein:

said communication of said estimated channel vector length is a first mode of operation for said data channel, wherein said communication via said data channel is subject to a substantial number of retransmissions.

27. A computer-readable medium of instructions as claimed in claim 25, wherein:

said first set of instructions is adapted to estimate said channel vector length based on an expected number of transmitted segments and an expected number of retransmitted segments for said communication.

28. A computer-readable medium of instructions as claimed in claim 25, wherein:

said first set of instructions is adapted to communicate said estimated channel vector length to said at least one node as part of a request to send (RTS) message.

29. A computer-readable medium of instructions as claimed in claim 25, wherein:

said second set of instructions is adapted to control said at least one node to communicate said estimated channel vector length to said first group of nodes as part of a clear to send (CTS) message.

30. A computer-readable medium of instructions as claimed in claim 25, wherein:

said third set of instructions is adapted to control said at least one node to monitor said data channel to detect at least one of a partial segment acknowledgement (ACK) message and an all segments good acknowledgement (ACK) message.

31. A computer-readable medium of instructions as claimed in claim 30, wherein:

said third set of instructions is adapted to control said at least one node to calculate an actual channel vector length based on said detected at least one of a partial segment acknowledgement (ACK) message and an all segments good acknowledgement (ACK) message.

32. A computer-readable medium of instructions as claimed in claim 25, wherein:

said fourth set of instructions is adapted to control said at least one node to communicate said actual channel vector length to said first group of nodes of said plurality as part of a request to send (RTS) message.

33. A computer-readable medium of instructions as claimed in claim 25, further comprising:

a fifth set of instructions, adapted to control said at least one node to calculate a checksum for a first node of said plurality and to communicate said checksum to a second node of said plurality as part of a request to send (RTS) message.

34. A computer-readable medium of instructions as claimed in claim 33, further comprising:

a sixth set of instructions, adapted to control said second node to update a channel vector database at said second node based on said RTS message.

35. A computer-readable medium of instructions as claimed in claim 25, wherein:

said second set of instructions is adapted to control said at least one node to communicate a maximum channel vector length to said first group of nodes as part of at least one of a clear to send (CTS) and request to send (RTS) message.

36. A computer-readable medium of instructions as claimed in claim 35, wherein:

said communication of said maximum channel vector length is a second mode of operation for said data channel, wherein said communication via said data channel is subject to a minimal number of retransmissions.