Method and apparatus for varying times/channels of broadcast beacons

• US 7,564,812 B1
• Filed: 06/06/2002
• Issued: 07/21/2009
• Est. Priority Date: 06/06/2002
• Status: Expired due to Fees

• Current Assignee: Raytheon BBN Technlogies Corp. (Rtx Corporation)
• Original Assignee: BBN Technologies (Rtx Corporation)
• Inventors: Elliott, Brig Barnum
• Primary Examiner(s): Phunkulh; Bob A
• Application Number:
  US10/164,237
• Time in Patent Office: 2,602 Days
• Field of Search: None
• US Class Current: 370/329
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 72/12 Wireless traffic scheduling
• CPC Class Codes: H04W 74/006 in the downlink, i.e. towards the terminal
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

Method and apparatus for varying the times and channels of broadcast beacons. The method and apparatus make it more difficult to monitor and/or disrupt such beacon transmissions. In one embodiment, pseudo-random times and pseudo-random channels are selected for transmitting the beacon messages. Preferably these times and channels are included in a beacon schedule which is transmitted with the beacon messages. In select embodiments, the beacon messages include schedules for both the transmitting node and other nodes, so that all of the nodes in the network may quickly learn the beacon schedules of the other nodes.

Claims

1. A method for a node to schedule transmission of a beacon message comprising:

selecting random times for transmitting the beacon message,

selecting random channels for transmitting the beacon-message;

generating a beacon transmission schedule for the node based on the selected times and channels; and

generating the beacon message, wherein the beacon message includes the beacon transmission schedule for the node transmitting the beacon message and additional beacon transmission schedules indicating when a plurality of other nodes will transmit beacons.

2. The method of claim 1, further comprising:

transmitting the beacon message by the node according to the selected times and channels of its beacon transmission schedule.

3. The method of claim 1, wherein the beacon message includes identification of the node transmitting the beacon message.

4. The method of claim 1, wherein the selecting steps comprise selecting a sequence of times and selecting a sequence of channels.

5. The method of claim 1, wherein the random times and random channels comprise one or more of:

pseudo-random number sequences;

physical random number sequences; and

unpredictable number sequences.

6. The method of claim 5, wherein the random times and random channels are pseudo-random number sequences.

7. The method of claim 1, wherein the beacon transmission schedules for the node and the plurality of other nodes each include transmission times for beacon messages in an ad hoc wireless network.

8. An apparatus for a network node to schedule transmission of a beacon message comprising:

a random number generator for generating random times for transmitting the beacon message and for generating random channels for transmitting the beacon message; and

a message generator for generating the beacon message, wherein the beacon message includes a beacon transmission schedule for the node based on the random times and the random channels and additional beacon transmission schedules indicating when a plurality of other network nodes will transmit beacons.

9. The apparatus of claim 8, further including a storage device for storing the beacon transmission schedule of the network node.

10. The apparatus of claim 8, further including a network node including a transmitter for transmitting beacon messages at the generated times and channels.

11. The apparatus of claim 10, wherein the transmitter generates beacon messages on wireless channels.

12. The apparatus of claim 11, wherein the wireless channels include at least one of radio, acoustic, magnetic, and infrared frequency channel.

13. The apparatus of claim 10, wherein the network node further includes a receiver for receiving beacon messages.

14. The apparatus of claim 8, wherein the apparatus further includes a transceiver and a power supply for selectively applying power to at least a portion of the transceiver.

15. The apparatus of claim 8, wherein the random number generator comprises one or more of a:

pseudo-random number generator;

physical random number generator; and

unpredictable number generator.

16. The apparatus of claim 15, wherein the random number generator is a pseudo-random number generator.

17. The apparatus of claim 8, wherein the beacon transmission schedules for the node and the plurality of other network nodes each include transmission times for beacon messages in an ad hoc wireless network.

18. A method of generating a beacon message comprising:

providing identifications of at least three nodes and random beacon transmission schedules for the at least three nodes, wherein each of the random beacon transmission schedules includes a time and a channel selected using a random selection process, and the random beacon transmission schedules indicate when the at least three nodes will transmit beacons; and

incorporating the identifications and schedules in the beacon message.

19. A method of receiving a beacon message comprising:

extracting a random beacon transmission schedule for a node from the message, wherein the random beacon transmission schedule includes a time and a channel selected using a random selection process;

extracting, from the beacon message, a plurality of additional random beacon transmission schedules indicating when a plurality of additional nodes will transmit beacons; and

listening at a receiver for another beacon message at a time and channel specified by one of the random beacon transmission schedules.

20. The method of claim 19, including powering on at least a portion of the receiver when a beacon message is expected to be transmitted according to the schedule.

21. An apparatus for generating a beacon message comprising:

a node having a node identifier;

a random number generator for generating a node beacon transmission schedule; and

a processor for generating a beacon message including the node identifier, the beacon transmission schedule, a plurality of additional node identifiers, and beacon transmission schedules indicating when a plurality of nodes identified by the plurality of additional node identifiers will transmit beacons.

22. An apparatus for transmitting beacons in a wireless ad hoc network comprising:

at least one node, said node

selecting random times and random channels for transmission of beacons,

storing the selected times and channels in at least one of at least three beacon transmission schedules, wherein the at least three beacon transmission schedules indicate when a plurality of nodes in the network will transmit beacons, and

transmitting beacons containing the at least three beacon transmission schedules.

23. The apparatus of claim 22, wherein the node is equipped with a wireless communications transceiver.

24. The apparatus of claim 22, wherein the node is at least one of a router capable of network routing functions, and an endpoint for data traffic.

25. Computer-executable software code stored on a computer-readable medium, the computer-executable code being for facilitating the transmission of beacons in a wireless network, the computer-executable code comprising:

computer-executable code for selecting random times and random channels for transmission of beacons;

computer-executable code for storing the selected times and channels in at least one of at least three beacon transmission schedules, wherein the at least three beacon transmission schedules indicate when a plurality of nodes in the network will transmit beacons; and

computer-executable code for transmitting beacons containing the at least three beacon transmission schedules.

26. A network communications apparatus comprising:

means for selecting random times and random channels for transmission of beacons;

means for storing the selected times and channels in at least one of at least three beacon transmission schedules, wherein the at least three beacon transmission schedules indicate when a plurality of nodes in the network will transmit beacons; and

means for transmitting beacons containing the at least three beacon transmission schedules.