Apparatus, and an associated method, for facilitating synchronization in a wireless mesh network

• US 7,180,915 B2
• Filed: 12/21/2001
• Issued: 02/20/2007
• Est. Priority Date: 12/21/2001
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: Nokia Corporation
• Inventors: Kasslin, Mika, Arrakoski, Jori, Beyer, David A.
• Primary Examiner(s): Patel; Ajit
• Application Number:
  US10/028,344
• Publication Number:
  US 20030117991A1
• Time in Patent Office: 1,887 Days
• Field of Search: 370/389, 370/391, 370/474, 370/503, 370/350, 370/512, 370/516, 370/520, 375/354, 375/371
• US Class Current: 370/516
• CPC Class Codes: H04B 7/2662 Arrangements for Wireless System Synchronisation
• CPC Class Codes: H04J 3/0667 Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays arrangements for monitoring round trip delays in packet switching networks H04L43/0864
• CPC Class Codes: H04W 4/18 Information format or content conversion, e.g. adaptation by the network of the transmitted or received information for the purpose of wireless delivery to users or terminals
• CPC Class Codes: H04W 40/248 Connectivity information update
• CPC Class Codes: H04W 56/00 Synchronisation arrangements

Abstract

Apparatus, and associated method, by which to synchronize nodes in a wireless mesh network, such as a fixed broadband network or a moving ad-hoc mesh network. Time stamps are added to data packets at a reference node defined pursuant to a pseudo hierarchy. The data packets are communicated by the reference node to a receiving node. The time stamp information is extracted therefrom, to provide an indication of a time reference value from which the time stamp information is formed. Registers are maintained at the nodes with updated values of the timing information, used in time synchronization between the nodes of the mesh network.

Claims

1. In a wireless mesh network having a first communication station and at least a second communication station, an improvement of apparatus for time-synchronizing communication of data between the first and at least second communication stations, respectively, said apparatus comprising:

a network time register coupled to receive a time reference signal of values representative of a reference time, said network time register for buffering and maintaining updated values of the reference time; and

a data formatter coupled to said network time register, said data formatter for formatting the data to be communicated between the first and at least second communication stations of the wireless mesh network, the data, once formatted, including indicia associated with the updated values of the reference time buffered at said network time register,

further comprising a latch register coupled to said network time register, said latch register for latching buffered values of the reference time buffered at said network time register.

2. The apparatus of claim 1 wherein a trigger signal is selectably applied to said latch register, and wherein the updated values of the reference time are buffered at said latch register and latched thereat upon application of, the trigger signal to said latch register.

3. The apparatus of claim 2 wherein the trigger signal is applied to said latch register responsive to occurrence of a selected event, buffering and latching at said latch register event-driven responsive to the occurrence of the selected event.

4. The apparatus of claim 3 wherein the latched values buffered at said latch register are accessible by at least a selected one of the first and at least second communication stations, the values accessible thereat representative of the reference time at which the selected event occurs.

5. The apparatus of claim 1 wherein said network time register forms a portion of a selected one of the first and at least second communication stations and wherein the selected one of the first and at least second communication stations at which said network time register is formed forms a time-reference communication station used by a nonselected at least one of the first and at least second communication stations to be synchronized thereto.

6. The apparatus of claim 1 wherein the data communicated between the first communication station and the at least the second communication station comprises packet data and wherein said data formatter formats the data into data packets of which at least selected ones of the data packets include the indicia associated with the updated values of the reference time.

7. The apparatus of claim 4 further comprising a strobe register coupled to said network time register, said strobe register for generating the trigger signal which is selectably applied to said latch register.

8. The apparatus of claim 7 wherein said strobe register is set with a strobe value, and wherein the trigger signal is generated each time in which the strobe value counts out.

9. The apparatus of claim 1 further comprising a clock oscillator, said clock oscillator for generating the time reference signal, values of which said network time register is coupled to receive.

10. The apparatus of claim 9 further comprising interface circuitry coupled to said clock oscillator and to said network time register, said interface circuitry coupled to receive an externally-generated master clock signal, and said interface circuitry for selectively biasing the clock oscillator to alter the time reference signal generated thereat.

11. The apparatus of claim 10 wherein said network time register, said data formatter, said clock oscillator, and said interface circuitry are formed at a selected one of the first communication station and the at least the second communication station and wherein the externally-generated master clock signal is generated by an other of the first and at least second communication stations, respectively.

12. In the wireless mesh network of claim 11, a further improvement of apparatus for the other of the first and at least second communication stations, said apparatus comprising an extractor for extracting the indicia associated with the updated values of the reference time when the data is communicated to the other of the first and at least second communication stations.

13. The apparatus of claim 12 wherein said network time register comprises a first network time register formed at the selected one of the first and at least second communication stations and a second time register formed at the other of the first and at least second communication stations, and wherein said data formatter comprises a first data formatter formed at the selected one of the first and at least second communication stations and a second data formatter formed at the other of the first and at least second communication stations.

14. In a method for communicating in a wireless mesh network having a first communication station and at least a second communication station, an improvement of a method for time-synchronizing communication of data between the first and at least second communication stations, respectively, said method comprising:

buffering and maintaining updated values of a reference time responsive to reception of a time reference signal of values representative of a reference time; and

formatting the data to be communicated between the first and at least second communication stations of the wireless mesh network, the data, once formatted, including indicia associated with the updated values of the reference time buffered during said buffering,

further comprising the operation of latching a buffered value of the reference time buffered during said buffering.

15. The method of claim 14 further comprising the operation of selectably generating a trigger signal and wherein said operation of latching is performed responsive to generation of the trigger signal.

16. The method of claim 15 wherein said operation of selectably generating the trigger signal is performed responsive to occurrence of a selected event.

17. The method of claim 14 wherein the data to be communicated between the first and at least second communication stations comprises packet data and wherein said operation of formatting comprises adding the indicia associated with the updated values of the reference time to at least select ones of data packets of the packet data.

18. The method of claim 17 wherein said operations of buffering and formatting are performed at the first communication station and wherein said method further comprises the operations of:

sending the packet data to the second communication station;

extracting the indicia associated with the updated values of the reference time from the at least selected ones of the data packets; and

using the indicia extracted during said operation of extracting to synchronize the second communication station to the reference time buffered during said operation of buffering and maintaining.