Distribution of synchronization in a synchronous optical environment

Claim 1

A method of passing synchronization through a network comprised of a plurality of nodes communicating with each other at a predetermined frame rate, the nodes communicating with each other through frames having predefined starts and with a line clock, the communication occurring by transmitting the frame and the line clock between nodes, the method comprising: generating at a first node a local timing reference signal at a frequency that is less than the frame rate; determining with the line clock at the first node the timing difference between a predetermined time of the frame and the local timing reference signal; and transmitting the timing difference to at least one other node in the network.

Claim 2

A method of passing synchronization through a network comprised of a plurality of nodes communicating with each other at a predetermined frame rate, the nodes communicating with each other through frames having predefined starts and with a line clock, the communication occurring by transmitting the frame and the line clock between nodes, the method comprising: generating at a first node a local timing reference signal at a frequency that is less than the frame rate; determining with the line clock at the first node the timing difference between a predetermined time of the frame and the local timing reference signal; and transmitting the timing difference to at least one other node in the network.

Claim 6

A method for maintaining synchronization in at least a portion of a network of a plurality of nodes, the network having a reference timing signal, each node in the network communicating with at least one other node in the network through frames having frame timing and each node generating a line clock and frame timing for communication with at least one other node, the method comprising: at at least one first node generating a local timing reference signal based at least in part upon the network reference timing signal; measuring the difference in timing at the first node between the frame timing for at least some frames being transmitted and the local timing reference signal; transmitting in at least some frames to at least one second node from the first node the measured time difference; and generating at the second node with the line clock, the frame timing and the transmitted measured time difference a reconstruction of the local timing reference signal such that at least one reconstructed local timing reference signal is synchronized to the network reference timing signal.

Claim 7

A method for maintaining synchronization in at least a portion of a network of a plurality of nodes, the network having a reference timing signal, each node in the network communicating with at least one other node in the network through frames having frame timing and each node generating a line clock and frame timing for communication with at least one other node, the method comprising: at at least one first node generating a local timing reference signal based at least in part upon the network reference timing signal; measuring the difference in timing at the first node between the frame timing for at least some frames being transmitted and the local timing reference signal; transmitting in at least some frames to at least one second node from the first node the measured time difference; and generating at the second node with the line clock, the frame timing and the transmitted measured time difference a reconstruction of the local timing reference signal such that at least one reconstructed local timing reference signal is synchronized to the network reference timing signal.

Claim 8

An apparatus for aiding the distribution of synchronization throughout a network comprising a plurality of nodes, each node generating a line clock having clock pulses at a predetermined frequency for transmitting information to another node and each node transmitting according to frames having a period based upon the timing of the frame that is being transmitted, the apparatus further including: a clock generator providing a timing reference signal having a period that is greater than the period of the frame rate; and a timing difference detector detecting a timing difference from time to time between a specific time in the frame and the timing reference signal.

Claim 9

An apparatus for aiding the distribution of synchronization throughout a network comprising a plurality of nodes, each node generating a line clock having clock pulses at a predetermined frequency for transmitting information to another node and each node transmitting according to frames having a period based upon the timing of the frame that is being transmitted, the apparatus further including: a clock generator providing a timing reference signal having a period that is greater than the period of the frame rate; and a timing difference detector detecting a timing difference from time to time between a specific time in the frame and the timing reference signal.

Claim 17

An apparatus for aiding the distribution of synchronization throughout a network comprised a plurality of nodes, each node regenerating a line clock at a predetermined frequency for receiving information from another node and each node receiving data according to frames having a period based upon the timing of the frame that is being received, the network further including transmission of information from a node related to the timing difference based upon the line clock between a predetermined portion of the frame and a timing reference signal, the apparatus further including: means for regenerating the line clock; means for regenerating timing associated with the received frame; and means for reconstructing the timing reference signal from the received information, the regenerated line clock and the regenerated frame timing.

Claim 18

An apparatus for aiding the distribution of synchronization throughout a network comprised a plurality of nodes, each node regenerating a line clock at a predetermined frequency for receiving information from another node and each node receiving data according to frames having a period based upon the timing of the frame that is being received, the network further including transmission of information from a node related to the timing difference based upon the line clock between a predetermined portion of the frame and a timing reference signal, the apparatus further including: means for regenerating the line clock; means for regenerating timing associated with the received frame; and means for reconstructing the timing reference signal from the received information, the regenerated line clock and the regenerated frame timing.

Claim 22

A method for generating synchronization throughout at least a part of a network based upon a master clock, each node of the at least part of the network having a node clock, whereby the phase timing of the node clock is synchronized to the timing of the master clock with network protocol including a predetermined timing relationship for the information being transmitted, the method including: measuring a timing difference between a reference signal and the predetermined timing relationship for the information being transmitted, the measurement being achieved with a predetermined granularity; transmitting the measurement to at least one other node where the measurement is received; synchronizing the clock of the node to the master clock using the received information, the timing relationship of the network and a filtering algorithm to provide a long term phase synchronization with the master clock at a resolution that is at least one order of magnitude smaller than the measuring granularity.

Claim 23

A method for generating synchronization throughout at least a part of a network based upon a master clock, each node of the at least part of the network having a node clock, whereby the phase timing of the node clock is synchronized to the timing of the master clock with network protocol including a predetermined timing relationship for the information being transmitted, the method including: measuring a timing difference between a reference signal and the predetermined timing relationship for the information being transmitted, the measurement being achieved with a predetermined granularity; transmitting the measurement to at least one other node where the measurement is received; synchronizing the clock of the node to the master clock using the received information, the timing relationship of the network and a filtering algorithm to provide a long term phase synchronization with the master clock at a resolution that is at least one order of magnitude smaller than the measuring granularity.

Claim 26

A method for transmitting timing information throughout at least part of a network, the network transmitting information during predetermined timing slots and a propagation delay existing in the network in the transmission of information between adjacent nodes, the method including: making a timing measurement based upon a timing reference and a timing information being transmitted during a first timing slot; transmitting the timing measurement during a subsequent timing slot; recovering the timing measurement at a second node during the immediately subsequent timing slot such that the timing information at the second node is recovered two timing slots plus a propagation delay after the first timing slot.

Claim 27

A method for transmitting timing information throughout at least part of a network, the network transmitting information during predetermined timing slots and a propagation delay existing in the network in the transmission of information between adjacent nodes, the method including: making a timing measurement based upon a timing reference and a timing information being transmitted during a first timing slot; transmitting the timing measurement during a subsequent timing slot; recovering the timing measurement at a second node during the immediately subsequent timing slot such that the timing information at the second node is recovered two timing slots plus a propagation delay after the first timing slot.

Claim 28

A method of passing synchronization through a network comprised of a plurality of nodes communicating with each other at a predetermined frame rate, the nodes communicating with each other through frames having predefined starts and with a line clock, the communication occurring by transmitting the frame and the line clock between nodes, the method comprising: generating at a first node a local timing reference signal; determining with the line clock at the first node the timing difference between a predetermined time of the frame being transmitted and the local timing reference signal; transmitting the timing difference to at least one other node in the network.

Claim 29

A method of passing synchronization through a network comprised of a plurality of nodes communicating with each other at a predetermined frame rate, the nodes communicating with each other through frames having predefined starts and with a line clock, the communication occurring by transmitting the frame and the line clock between nodes, the method comprising: generating at a first node a local timing reference signal; determining with the line clock at the first node the timing difference between a predetermined time of the frame being transmitted and the local timing reference signal; transmitting the timing difference to at least one other node in the network.

Claim 33

An apparatus for aiding the distribution of synchronization throughout a network comprising a plurality of nodes, each node generating a line clock having clock pulses at a predetermined frequency for transmitting information to another node and each node transmitting according to frames having a period based upon the timing of the frame that is being transmitted, the apparatus further including: a clock generator providing a timing reference signal; and a timing difference detector detecting a timing difference from time to time between a specific time in the frame being transmitted and the timing reference signal.

Claim 34

An apparatus for aiding the distribution of synchronization throughout a network comprising a plurality of nodes, each node generating a line clock having clock pulses at a predetermined frequency for transmitting information to another node and each node transmitting according to frames having a period based upon the timing of the frame that is being transmitted, the apparatus further including: a clock generator providing a timing reference signal; and a timing difference detector detecting a timing difference from time to time between a specific time in the frame being transmitted and the timing reference signal.