SYNCHRONIZATION OF DISTRIBUTED NODES

• US 20150173034A1
• Filed: 09/23/2014
• Published: 06/18/2015
• Est. Priority Date: 09/23/2013
• Status: Active Grant

• Current Assignee: Ziva Corporation
• Original Assignee: Ziva Corporation
• Inventors: RODE, Jeremy, SMITH, David, HUSAIN, Anis, HSU, Mark
• Granted Patent: US 10,021,659 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/0617 for beam forming
• CPC Class Codes: H04W 56/001 Synchronization between nodes
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

Dynamic, untethered array nodes with internal clocks are frequency, phase, and time aligned/synchronized, and used to focus their transmissions of the same payload data coherently on a target or in the target'"'"'s direction, using time reversal or directional beamforming. Information for alignment/synchronization may be sent from a master node of the array to the slave nodes, over RF node-to-node links operating on different carrier or subcarrier frequencies. Additionally, the up- and down-communications on the RF links may use different frequencies. The RF links may also be used to distribute the payload data across the array. Because of frequency division on the RF links, interference is reduced or avoided, and the process of alignment/synchronization may be performed concurrently for several or all the slave nodes. The array may also operate collaboratively to receive data from the target.

Claims

1. A method of communicating between an array of ad hoc nodes and a target, the array comprising a master node and a plurality of slave nodes, the method comprising steps of:

communicating between the master node and each slave node of the array to enable synchronization of said each slave node to the master node, the step of communicating with said each slave node being performed on a radio frequency (RF) side channel link associated with said each slave node, wherein a plurality of RF side channel links are established by the array, each RF side channel link operating on an upward frequency for transmissions to the master node and on a downward frequency for transmissions from the master node;

performing frequency, time, and phase synchronization of said each slave node to the master node based on the step of communicating;

distributing across the array common data for transmission to the target; and

coherently transmitting from said each node of the array to the target signals at a common RF frequency, the signals at the common frequency carrying the common data, so that the signals carrying the common data add constructively in a general direction from the array to the target and/or in a general location of the target, the step of coherently transmitting comprising directional beamforming or location-focusing using time-reversal;

wherein;

the plurality of slave nodes comprises a first slave node associated with a first RF side channel link, and a second slave node associated with a second RF side channel link;

the first RF side channel link operates at a first upward frequency from the first slave node to the master node and on a first downward frequency from the master node to the first slave node;

the second RF side channel link operates at a second upward frequency from the second slave node to the master node and on a second downward frequency from the master node to the second slave node; and

at least one frequency selected from the group consisting of the first upward frequency, the second upward frequency, the first downward frequency, and the second downward frequency is different from at least one other frequency selected from the group.

2. A method as in claim 1, wherein the step of communicating is performed in parallel for at least two slave nodes of the plurality of slave nodes.

3. A method as in claim 1, wherein the step of communicating is performed in parallel for the plurality of slave nodes.

4. A method as in claim 1, wherein each frequency of the group is a carrier frequency.

5. A method as in claim 1, wherein each frequency of the group is a subcarrier frequency.

6. A method as in claim 1, wherein the common frequency is different from upward and downward frequencies of every RF side channel link of the array.

7. A method as in claim 1, wherein upward frequency of RF side channel link of said each slave node is different from upward frequency of RF side channel of every other slave node of the array, and downward frequency of RF side channel link of said each slave node is different from downward frequency of RF side channel link of every other slave node of the array.

8. A method as in claim 1, wherein:

upward frequency of RF side channel link of said each slave node is different from upward frequency of RF side channel of every other slave node of the array and from downward frequency of every slave node of the array; and

downward frequency of RF side channel link of said each slave node is different from downward frequency of RF side channel link of every other slave node of the array.

9. A method as in claim 6, wherein the common frequency is different from upward and downward frequencies of every RF side channel link of the array.

10. A method as in claim 1, further comprising keeping the array in a state-of-readiness after the step of communicating and before the step of performing synchronization until occurrence of a predetermined trigger event.

11. An array of nodes for collaborative communication with a target, wherein:

the array comprises a master node and a plurality of slave nodes, the plurality of slave nodes comprising a first slave node and a second slave node;

each node of the array comprises a processor;

radio frequency circuitry (RF) operating under control of the processor, and memory coupled to the processor and storing instructions executable by the processor;

the nodes are configured to;

establish a plurality of RF side channel links, an RF side channel link per slave node, each slave node of the plurality of slave nodes communicating with the master node over the RF side channel link corresponding to said each slave node to enable frequency, time, and phase synchronization of said each slave node to the master node, each RF side channel link of the plurality of side channel links operating on an upward frequency for transmissions to the master node and on a downward frequency for transmissions from the master node, the plurality of RF side channel links comprises a first side channel link corresponding to the first slave node and a second side channel link corresponding to the second slave node,

perform frequency, time, and phase synchronization of said each slave node to the master node based on the communications over the RF side channel links,

distribute across the array common data for transmission to the target, and

coherently transmit from said each node of the array to the target signals at a common RF frequency, the signals at the common frequency carrying the common data, so that the signals carrying the common data add constructively in a general direction from the array to the target and/or in a general location of the target, the step of coherently transmitting comprising directional beamforming or location-focusing using time-reversal;

the first RF side channel link operates at a first upward frequency from the first slave node to the master node and on a first downward frequency from the master node to the first slave node;

the second RF side channel link operates at a second upward frequency from the second slave node to the master node and on a second downward frequency from the master node to the second slave node; and

at least one frequency selected from the group consisting of the first upward frequency, the second upward frequency, the first downward frequency, and the second downward frequency is different from at least one other frequency selected from the group.

12. An array of nodes as in claim 11, wherein the nodes are further configured to enable the plurality of slave nodes to obtain synchronization information in parallel.

13. An array of nodes as in claim 11, wherein each frequency of the group is a carrier frequency.

14. An array of nodes as in claim 11, wherein each frequency of the group is a subcarrier frequency.

15. An array of nodes as in claim 11, wherein each frequency of the group is a subcarrier frequency.

16. An array of nodes as in claim 11, wherein the common frequency is different from upward and downward frequencies of every RF side channel link of the array.

17. An array of nodes as in claim 11, wherein:

upward frequency of RF side channel link of said each slave node is different from upward frequency of RF side channel of every other slave node of the array and from downward frequency of every slave node of the array; and

downward frequency of RF side channel link of said each slave node is different from downward frequency of RF side channel link of every other slave node of the array.

18. An array of nodes as in claim 17, wherein the common frequency is different from upward and downward frequencies of every RF side channel link of the array.

19. An array of nodes as in claim 11, wherein the nodes are further configured to remain in a state-of-readiness after frequency, time, and phase synchronization of said each node is enabled, and to synchronize in response to occurrence of a predetermined trigger event.

20. An array of nodes as in claim 11, wherein:

the master node comprises means for synchronizing slave nodes; and

each slave node comprises means for synchronizing to the master node.