A clock determining method includes: when both a second network device and a first network device are synchronous with a reference clock, simulating, by using delay information between the second network device and the first network device and clock frequency information of the second network device, a second virtual clock synchronized with a first virtual clock, where the first virtual clock is used to simulate a clock of the first network device. A clock of the second network device can thus be simulated to perform a subsequent operation by using the simulated clock. For example, the simulated clock may be used to estimate precision time protocol (PTP) message synchronization performance of the second network device. Therefore, the PTP message synchronization performance of the second network device may be pre-determined before a global navigation satellite system (GNSS) fails, to guide network operation and maintenance activities.

Provided are a time synchronization method using 5G reference time distribution and a network entity performing the same. The time synchronization method may include receiving, by a time sensitive communication time synchronization function (TSCTSF), a 5G reference time distribution request including time synchronization parameter values from an application function (AF); performing, by the TSCTSF, policy modification; and transmitting, by the TSCTSF, a setting of the 5G reference time distribution to the AF.

The invention relates to a method for providing a fault-tolerant global time via a time server in a distributed real-time computer system, wherein the time server comprises four components which are connected to one another via a bi-directional communication channel. At a priori defined periodic, internal synchronization times, each of the four components transmits an internal synchronization message, which is simultaneously transmitted to the other three components, from which each internal computer of a component determines a correction term for the tick counter contained in its component and corrects the reading of the local tick counter by this correction term.

Systems and methods for implementing a software emulation of a clock calibrated by the software based on sampling a hardware clock.

A method for processing a time synchronization packet is provided. In an embodiment a terminal device receives a time synchronization packet of a first clock source from an external device; receives first indication information from a network device, where the first indication information instructs the terminal device to enter a time synchronization activated state of the first clock source, or the first indication information instructs the terminal device to enter a time synchronization deactivated state of the first clock source; and processes the time synchronization packet of the first clock source based on the first indication information. When a clock source is activated and deactivated, the terminal device processes a time synchronization packet of the clock source in different manners, and signaling indicates whether the clock source is activated or deactivated.

Disclosed are systems, methods, and non-transitory computer-readable media for clock synchronization in half-duplex communication systems. Devices in a half-duplex system are synchronized based on time stamp values captured by each device that define a specified period of time that is of equal in length. The specified period of time spans two change-over periods to average the jitter and/or drift that occurs during each period. Each device uses these measured lengths to determine the variance in the rates at which the two internal clocks operates, which is then used to synchronizes the internal clocks of the two devices.

Embodiments of the present disclosure relate to methods, optical line terminals (OLTs), optical network units (ONUs), apparatuses and computer storage media for transmitting a time synchronization message. In some example embodiments, the OLT is configured to: determine a threshold rate to be N messages per second for transmission of a time synchronization message to an ONU, wherein N being greater than or equal to 0.1; and transmit, to the ONU, a time synchronization message at the threshold rate or a rate above the threshold rate, to enable the ONU to perform time synchronization with the OLT. In some other example embodiments, the OLT is configured to: select a plurality of ONUs for transmitting time synchronization information; and transmit, to the ONUs, a broadcast or multicast message the time synchronization information, to enable the plurality of ONUs to perform time synchronization with the OLT.

The present aspects relate to techniques of timing synchronization of audio and video (AV) data in a network. In particular, the techniques for a AV master to distribute AV data encoded with one or more time markers to a plurality of processing nodes. The one or more time markers may be indexed to a precision time protocol (PTP) time stamp used as a time reference. In one technique, the nodes extract the time markers to determine an offset value that is applied to a PLL to synchronize AV data packets at a distribution node or a processing node. In another technique the distribution node or the processing node determines the worst case path, which corresponds to a system offset value. The distribution node then reports the system offset value to the AV master, which in turn adjusts the phase based on the report.

Disclosed herein is a method, a computer program product, and a carrier for indicating one-way latency in a data network (N) between a first node (A) and a second node (B), wherein the data network (N) lacks continuous clock synchronization, comprising: a pre-synchronisation step, a measuring step, a post-synchronisation step, an interpolation step, and generating a latency profile. The present invention also relates to a computer program product incorporating the method, a carrier comprising the computer program product, and a method for indicating server functionality based on the first aspect.

A wireless media distribution system is provided comprising an access point (6) for broadcasting media and a plurality of stations (2) for reception and playback of media. Each station is configured for receiving and decoding a timestamp in a beacon frame transmitted repeatedly from the access point. This is used to control the output signal of a station physical layer clock (12) which is then used as a clock source for an application layer time synchronisation protocol. This application layer time synchronisation protocol can then be used in the station to control an operating system clock (8) for regulating playback of media.