Low-power autonomous node for mesh communication network

• US 20060029061A1
• Filed: 10/06/2004
• Published: 02/09/2006
• Est. Priority Date: 03/27/2004
• Status: Active Grant

• Current Assignee: Analog Devices International Unlimited Company (Analog Devices, Inc.)
• Original Assignee: Dust Networks Incorporated (Analog Devices, Inc.)
• Inventors: Zats, Yuri S., Treuhaft, Noah, Pister, Kristofer S.J., Conant, Rob
• Granted Patent: US 7,529,217 B2
• Time in Patent Office: Days
• US Class Current: 370/389
• CPC Class Codes: H04W 40/02 Communication route or path selection, e.g. power-based or shortest path routing
• CPC Class Codes: H04W 52/0222 in packet switched networks
• 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

In a packet communication network, a method and apparatus for packet switched transport is provided among intelligent nodes wherein the duty cycling of the intelligent nodes is minimized in order to maximize power life using a synchronization algorithm that assures all nodes are able to propagate information through the network without undue use of transmission and reception power. Frequency hopping time-division multiple access supports packet communication between intelligent nodes via assigned directed links, each link being assigned to a time-channel offset (cell) in a superframe, so that a link carrying a packet string between any two intelligent nodes is active only during its assigned time slot. The result is efficient use of spectrum and minimal expenditure of power.

Claims

1. In a packet communications network having a mesh structure of at least first, second and third intelligent nodes, each said intelligent node comprising:

a receiver capable of receiving packets on at least one preselected channel;

a transmitter capable of transmitting packets to at least said second intelligent node via at least said third intelligent node;

data storage for storing information containable in packets and information about directed links to at least said second and said third intelligent nodes;

an autonomous power source;

an internal time reference; and

a controller for selecting modes of power consumption, said controller coupled to said internal time reference and to said data storage, said controller being operative to manage power consumption of itself while maintaining communication with other intelligent nodes according to a schedule for point-to-point communication.

2. The intelligent node of claim 1 wherein power consumption management includes time synchronization suited to a time/frequency communication cycle agreed upon among said nodes.

3. In a packet communications network having a plurality of frequency-agile communication intelligent nodes capable of receiving packets on any of a plurality of preselected channels and capable of transmitting packets on any of said plurality of preselected channels, a method for communicating via links between a first intelligent node and a second intelligent node via at least a third intelligent node comprising:

establishing a digraph including a least a first directional link from said first intelligent node to said third intelligent node and a second directional link from said third intelligent node to said second intelligent node; and

providing a frequency hopping time-division multiple access superframe having time/frequency slots to support packet communication between said first intelligent node and said second intelligent node via said second link, each said time/frequency slot in said superframe being assigned to a corresponding single directional link, so that each said directional link that is operative to carry a packet string between any two of said intelligent nodes is active only during its assigned time slot in order to conserve energy.

4. In a multi-hop packet-switched communication network, a method for routing packets comprising:

providing at least a first intelligent node and a second intelligent node, said first intelligent node and said second intelligent node serving as intelligent nodes in said packet communication network and each said first intelligent node and said second intelligent node having independent intelligence for storing and redirecting units of communication traffic;

providing at least one digraph, each said digraph being expressed as routing information for directional links at each intelligent node in the network, including at least a first intelligent node having a plurality of outgoing directional links from said first intelligent node to a second intelligent node;

generating a plurality of packets, each of said packets having a header;

directing, via said routing information at each said intelligent node, said packets to flow between selected ones of said intelligent nodes according to one of said digraphs in accordance with a synchronized time and frequency communication plan;

otherwise

turning off transmission and receiving elements of said intelligent nodes to minimize power consumption when not receiving and directing said packets.

5. The method according to claim 4 wherein, at each said individual intelligent node that is operative to receive a packet, determining:

a) whether the packet is intended for said individual intelligent node; and

b) whether the packet is of interest to said individual intelligent node.

6. The method according to claim 5 wherein selected ones of said individual intelligent nodes determine that the packet is intended for itself if said individual intelligent node has no outgoing links in the digraph.

7. The method according to claim 5 wherein selected ones of said individual intelligent nodes determine that the packet is intended for itself from comparison of information at said individual intelligent node with the packet.

8. The method according to claim 5 wherein each directed link in said digraph is specific to a time slot in a time-frequency space.

9. The method according to claim 4 wherein at least one said packet is assigned to a position in a selected time slot of fixed duration that is substantially longer in duration than any packet, wherein all said time slots are assembled into a superframe consisting of a variable number of said time slots;

and wherein each one of said time slots is assigned to a selected frequency channel.

10. The method according to claim 9 wherein each directed link in said digraph is specific to an assigned slot in time-frequency space.

11. The method according to claim 5 wherein each said intelligent node is operative to determine that a received packet is of interest to itself if a specific destination pattern described in the received packet matches said intelligent node.

12. The method according to claim 11 wherein a specific destination pattern includes a WAN connection at said intelligent node

13. The method according to claim 9 wherein said at least one said intelligent node determines that a received packet is of interest to itself if a specific destination pattern described in the received packet matches with said intelligent node.

14. The method according to claim 13 wherein a specific destination pattern includes a measured temperature at said intelligent node is within a preselected range

15. The method according to claim 9 wherein said determining step comprises:

detecting whether a “

time to live”

field has expired.

16. The method according to claim 9 wherein said determining step comprises:

detecting whether the received packet has requested an action of which said intelligent node is capable; and

, if said intelligent node is capable of the requested action,

taking the requested action.

17. The method according to claim 16 wherein said requested action comprises:

extracting a payload of the packet out of the network; and

sending the payload to a destination via the Internet.

18. The method according to claim 16 wherein said requested action comprises:

extracting a payload of the packet out of the mesh network; and

causing a specific task that is local to said intelligent node to be performed.

19. The method according to claim 4 wherein superframe offsets, an identification tag of each intelligent node, a password, and selected information known to both ends of a directed link of a selected digraph are operative to move both channel and time slots with respect to time.

20. The method according to claim 4 wherein each intelligent node sets its local clock with respect to a central reference upon arrival of a start symbol to convey timing information.

21. The method of claim 4 further including determining frame for a received packet by reference to the time slot of arrival of the received packet with respect to a central reference time.

22. The method of claim 4 further including determining exact time offset from the time of arrival of the received packet.

23. The method of claim 4 further including determining exact time offset from the time of arrival of an ACK associated with the received packet.

24. The method of claim 4 further including using multi-cast links to cause flow of timing information into the network.

25. The method of claim 4 further including updating and compensating for a internal time skew error estimate using average of recent tick updates from parent intelligent nodes.

26. The method of claim 4 further including subdividing the network tinto subnetworks o provide local dataflow and control without dependence on communication with a central controller for each transaction.