Wireless communication system and related methods

• US 8,126,488 B2
• Filed: 04/21/2006
• Issued: 02/28/2012
• Est. Priority Date: 04/22/2005
• Status: Active Grant

• Current Assignee: Zenner Performance Meters, Inc. (Zenner International GmbH & Co. KG)
• Original Assignee: Axiometric, LLC
• Inventors: Albert, David, Cornelius, Steve, Martinez, John
• Primary Examiner(s): Ajibade Akonai, Olumide T
• Assistant Examiner(s): Peaches, Randy
• Application Number:
  US11/408,053
• Publication Number:
  US 20060239333A1
• Time in Patent Office: 2,139 Days
• Field of Search: 455/502, 370/436, 370/312, 370/314, 370/432, 370/442
• US Class Current: 455/502
• CPC Class Codes: H04W 56/002 Mutual synchronization
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: H04W 8/005 Discovery of network devices, e.g. terminals
• CPC Class Codes: H04W 84/18 Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

A method of operating a wireless mesh network comprises generating a pseudorandom sequence element in a transmitting device and a receiving device of the network using information shared by the transmitting and receiving devices. The pseudorandom sequence element is then used to calculate a communication channel/timeslot assignment for communication between the transmitting wireless device and the receiving wireless device.

Claims

1. A method of coordinating communication between a plurality of wireless devices, the method comprising:

generating a pseudorandom sequence element in a transmitting wireless device by operation of a first pseudorandom sequence generator (PSG) located in the transmitting wireless device;

generating a pseudorandom sequence element in a receiving wireless device by operation of a second PSG located in the receiving wireless device;

calculating a communication channel/timeslot assignment for communication between the transmitting wireless device and the receiving wireless device based on the pseudorandom sequence element; and

transmitting data from the transmitting wireless device to the receiving wireless device according to the communication channel/timeslot assignment,

wherein the first and second pseudorandom sequence generators are seeded with information that is shared by the plurality of wireless devices,

wherein where the receiving wireless device has more than one adjacent wireless device transmitting data during a timeslot in which the receiving wireless device is receiving data, the receiving wireless device decides to receive data transmitted by the transmitting device using random selection or a heuristic technique,

wherein the information that is shared by the plurality of wireless devices comprises a combination of a reference clock time and a plurality of unique device identifiers,

wherein the reference clock time is derived from a common global reference clock time that is shared by the plurality of wireless devices,

wherein each of the plurality of wireless devices contains a local clock adapted to maintain the reference clock time,

wherein said method further comprises expanding a timeslot window for transmitting or receiving data in at least one of the plurality of wireless devices to compensate for drift of the local clock, and

wherein maintaining the reference clock time comprises;

receiving a transmission encoding a global reference clock time and a new timing age indicating an amount of elapsed time since the global reference clock time was transmitted from a global reference clock time source;

determining whether the new timing age is less than a current timing age associated with the local clock;

upon determining that the new timing age is less than the current timing age, updating the local clock with the global reference clock time and updating the current timing age with the new timing age; and

incrementing the local clock and the current timing age at regular time intervals.

2. The method of claim 1, wherein maintaining the reference clock time further comprises:

incrementing the timing age each time the local clock is updated with the global reference clock time.

3. The method of claim 1, wherein expanding the timeslot window comprises:

determining a rate of the local clock drift;

measuring an elapsed time since a last update of the timeslot window, and

expanding the size of the timeslot window by an amount proportional to the elapsed time multiplied by the rate of the local clock drift.

4. The method of claim 1, further comprising:

by operation of the transmitting wireless device, determining a timing age associated with an adjacent wireless device; and

transmitting data from the transmitting wireless device to the adjacent wireless device based on whether the current timing age is greater than or less than the respective timing ages of other adjacent wireless devices.

5. The method of claim 1, further comprising:

by operation of the receiving wireless device, determining a timing age associated with an adjacent wireless device; and

processing data from the adjacent wireless device based on whether the current timing age is greater than or less than the respective timing ages of other adjacent wireless devices.

6. The method of claim 1, wherein the first and second PSGs each comprise a maximal-length pseudorandom sequence generator.

7. The method of claim 1, further comprising:

disregarding the received time if the timing age exceeds a predetermined threshold value.

8. The method of claim 1, wherein transmitting data from the transmitting wireless device to the receiving wireless device according to the communication channel/timeslot assignment comprises:

tuning a transmitter of the transmitting wireless device and a receiver of the receiving wireless device to a communication channel specified by the communication channel/timeslot assignment; and

transmitting the data from the transmitting wireless device to the receiving wireless device during a timeslot specified by the channel/timeslot assignment.

9. A method of coordinating communication between a plurality of wireless devices, the method comprising:

generating a pseudorandom sequence element in a transmitting wireless device by operation of a first pseudorandom sequence generator (PSG) located in the transmitting wireless device;

generating a pseudorandom sequence element in a receiving wireless device by operation of a second PSG located in the receiving wireless device;

calculating a communication channel/timeslot assignment for communication between the transmitting wireless device and the receiving wireless device based on the pseudorandom sequence element; and

transmitting data from the transmitting wireless device to the receiving wireless device according to the communication channel/timeslot assignment,

wherein the first and second pseudorandom sequence generators are seeded with information that is shared by the plurality of wireless devices,

wherein the information that is shared by the plurality of wireless devices comprises a combination of a reference clock time and a plurality of unique device identifiers,

wherein the reference clock time is derived from a common global reference clock time that is shared by the plurality of wireless devices,

wherein each of the plurality of wireless devices contains a local clock adapted to maintain the reference clock time, and

wherein maintaining the reference clock time comprises;

receiving a transmission encoding a global reference clock time and a new timing age indicating an amount of elapsed time since the global reference clock time was transmitted from a global reference clock time source;

determining whether the new timing age is less than a current timing age associated with the local clock;

upon determining that the new timing age is less than the current timing age, updating the local clock with the global reference clock time and updating the current timing age with the new timing age;

incrementing the local clock and the current timing age at regular time intervals; and

expanding a timeslot window for transmitting or receiving data in at least one of the plurality of wireless devices to compensate for drift of the local clock.

10. The method of claim 9, wherein maintaining the reference clock time further comprises incrementing the timing age each time the local clock is updated with the global reference clock time.

11. The method of claim 9, wherein expanding the timeslot window comprises:

determining a rate of the local clock drift;

measuring an elapsed time since a last update of the timeslot window, and

expanding the size of the timeslot window by an amount proportional to the elapsed time multiplied by the rate of the local clock drift.

12. The method of claim 9, further comprising:

by operation of the transmitting wireless device, determining a timing age associated with an adjacent wireless device; and

transmitting data from the transmitting wireless device to the adjacent wireless device based on whether the current timing age is greater than or less than the respective timing ages of other adjacent wireless devices.

13. The method of claim 9, further comprising:

by operation of the receiving wireless device, determining a timing age associated with an adjacent wireless device; and

processing data from the adjacent wireless device based on whether the current timing age is greater than or less than the respective timing ages of other adjacent wireless devices.

14. The method of claim 9, wherein the first and second PSGs each comprise a maximal-length pseudorandom sequence generator.

15. The method of claim 9, further comprising disregarding the received time if the timing age exceeds a predetermined threshold value.

16. The method of claim 9, wherein transmitting data from the transmitting wireless device to the receiving wireless device according to the communication channel/timeslot assignment comprises:

tuning a transmitter of the transmitting wireless device and a receiver of the receiving wireless device to a communication channel specified by the communication channel/timeslot assignment; and

transmitting the data from the transmitting wireless device to the receiving wireless device during a timeslot specified by the channel/timeslot assignment.