摘要:
A device for controlling frequency synchronization includes a processor (101) for controlling a phase-controlled clock signal to achieve phase-locking between the phase-controlled clock signal and a reference clock signal, and for controlling a frequency-controlled clock signal so as to achieve frequency-locking between the frequency-controlled clock signal and the reference clock signal. The processor is also configured to monitor a deviation between the frequency- and phase-controlled clock signals, detect a change of circumstances such as temperature changes causing frequency drifting of the frequency-controlled clock signal, and replace or correct the frequency-controlled clock signal with or on the basis of the phase-controlled clock signal when both the monitored deviation and the detected change of circumstances show correlation confirming frequency drift of the frequency-controlled clock signal. Thus, the phase-controlled clock signal together with the information about possible changes in the circumstances is used for improving the quality of the frequency-controlled clock signal.
摘要:
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 (501, 502) between the two areas of the communication system in both transmission directions. Values of the time difference are calculated (503) 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 (504) 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 (504).
摘要:
A device for controlling frequency synchronization includes a processor for controlling a frequency-controlled clock signal on the basis of received timing messages so as to achieve frequency-locking between the frequency-controlled clock signal and a reference clock signal. For the purpose of finding such timing messages which have experienced similar transfer delays and thus are suitable for the frequency control, the processor is configured to control a phase-controlled clock signal on the basis of the timing messages so as to achieve phase-locking between the phase-controlled clock signal and the reference clock signal, and to select the timing messages to be used for the frequency control on the basis of phase-error indicators related to the phase control. Thus, the phase-controlled clock signal is an auxiliary clock signal that is utilized for performing the frequency control.
摘要:
A device for controlling a clock signal generator includes a processor (101) 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.
摘要:
The invention relates to transferring of a time of day value between network elements of a data transfer network. It has been surprisingly detected that the phase reference signals available to various network elements can be utilized in the synchronization of time of day values between these network elements. In the solution according to the invention, a first network element sends to a second network element a difference variable (401, 402, 403) that indicates how much the timing phase of the time of day value maintained in the first network element differs from the timing phase of the phase reference signal available to the first network element. In the second network element that receives the message, an estimate of the time of day value is formed (404, 405) based on the difference variable and the timing phase of the phase reference signal available to the second network element.
摘要:
A method and apparatus for monitoring and limiting the transmission speed of a data traffic flow in a situation where the traffic flow also includes delay-critical traffic. With the sending of each protocol data unit it is determined whether the sending of the next protocol data unit should be delayed in order to meet a condition set on the transmission speed. It is also determined whether the transfer speed of delay-critical traffic meets a preset condition. If the transfer speed meets the condition, delay-critical protocol data units will not be delayed but if the condition is not met, delay-critical protocol data units will be delayed just like non-delay-critical protocol data units. Thus the transfer speed of non-delay-critical traffic adapts to variations in the transfer speed of delay-critical traffic and, furthermore, the transmission speed of the traffic flow can be monitored and limited.
摘要:
In a data communication system according to the invention the functionality of the gateway device is distributed in a data communication network thereby reducing the need to direct the data traffic from and to terminals (212, 213, 214) through a single point in the data communication network. A first data communication device (207) is arranged to make, through signalling, second data communication devices (204, 205, 206) capable of directing the data communications of the terminals to the starting points of the respective logical data communication tunnels (215, 216, 217). This way there is no need for all logical data communication tunnels to start from, or depending on the direction, to end at, the same point in the data communication network.
摘要:
In a system, the functionality is decentralized in a data transmission network so that the need of communications produced by and addressed to data terminals to pass by way of a single point in the data transmission network is diminished. A first data transmission installation is adapted to signal second data transmission installations, each of which is part of a ring-shaped data transmission topology, to be capable of building logical data transmission tunnels directed to the data terminals. Thereby, all the logical data transmission tunnels need not commence or, depending on the direction, terminate at the same point of a data transmission network. In addition, the data transmission installations present in a ring-shaped data transmission topology need not necessarily be taught routing information in order to enable each of these data transmission installations to send data transmission frames to be transmitted to another one of these data transmission installations.