Tellabs Oy

Coriant Oy

Jonas Lundqvist

Kenneth Hann

Heikki Laamanen

Mikko Laulainen

Markus Hurme

A device () for controlling a clock signal generator includes a processing system configured to form a control quantity at least partly on the basis of reception moments of data frames belonging to a given flow, the reception moments being time values based on a clock signal prevailing at a receiver. The processing system controls the clock signal generator with the control quantity so as to achieve synchronization between the clock signal and another clock signal in accordance of which the data frames have been transmitted. In order to identify data frames belonging to the relevant flow, the processing system checks whether pre-determined bits of a received data frame constitute a bit pattern that occurs when the data frame belongs to the relevant flow. Therefore, the reception moments of data frames belonging to the relevant flow are obtainable without deep inspection of the received data frames.

Method and a device for controlling a clock signal generator

A device for controlling a clock signal generator includes a processor () for forming at least two mutually different control quantities on the basis of reception moments of timing messages such as time stamps, where the reception moments are expressed as time values based on a first clock signal and the timing messages are transmitted in accordance with a second clock signal. The processor also calculates a weighted sum of the control quantities, and controls the clock signal generator with the weighted sum so as to synchronize the first clock signal and the second clock signal. The control quantities may represent, for example, a filtered value of observed phase-errors, a phase-error corresponding to a minimum observed transfer delay, and phase-errors corresponding to a given portion of the delay distribution. Using the weighted sum of the mutually different control quantities improves the utilization of the information content of the timing messages.

An arrangement for adjusting a clock signal in a network element of a communications network includes a processor device arranged to produce a control variable containing information about synchronization messages received from at least two other network elements. A situation in which the reception from a sending network element of synchronization messages of a good enough quality ceases will not significantly disturb the clock signal to be adjusted because only part of the control variable used for the adjustment depends on synchronization messages sent by an individual network element. In a preferred arrangement, the reference value of the control variable is changed in response to a situation where the reception from a sending network element of synchronization messages of a good enough quality ceases. Thus it is possible to reduce the change of the difference between the control variable and its reference value which further reduces disturbances caused in the clock signal to be adjusted.

Method and arrangement for adjustment of a clock signal

The invention relates to determining a quantity to be measured from a communication system, such as a transmission delay or the phase difference of clock times. Measurement messages are transmitted () between the two areas of the communication system in both transmission directions. Values of the time difference are calculated () for the measurement messages transmitted in at least one of the transmission directions, each of which values is the difference between the instant of reception measured at the reception and the instant of transmission measured at the transmission of the measurement message. The values of the time difference are used to calculate () an estimate of the distribution of the time difference, on the basis of which an estimate of the minimum value of the time difference is calculated ().

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Espoo, Finland

Jonas Lundqvist