This application discloses a time synchronization fault processing method, apparatus, and system, and belongs to the communication field. The method includes: When time of a first translator in a first network is not synchronized with a clock source in the first network, the first translator stops communicating time information with at least one other translator in the first network than the first translator, where the time information is used for obtaining time synchronized with a clock source in a second network.

A communication method and apparatus are provided. The method includes: receiving a first time difference from a second communication apparatus; determining a round trip time RTT based on the first time difference and a second time difference; and sending a second message to a terminal device, where the second message includes the RTT, an air interface propagation delay, or terminal device side timing information, a value of the air interface propagation delay is equal to half of a value of the RTT, and the terminal device side timing information is determined based on the air interface propagation delay. According to the method and the apparatus in embodiments of this application, high-precision timing between a network device and the terminal device in a CU-DU separation architecture can be implemented.

A method includes receiving a current velocity and a current position of a mobile node relative to a fixed node. The method also includes identifying a receive time slot for the fixed node to receive a transmission of a data packet from the mobile node and determining a propagation delay for the data packet between the mobile node and the fixed node based on the current position of the mobile node. The method includes determining a transmission time based on the receive time slot and the propagation delay and determining a Doppler shift based on the current velocity of the mobile node. The method includes determining a transmission frequency based on the Doppler shift and a clock rate correction. The method also includes transmitting the data packet to the fixed node at the determined transmission time using the determined transmission frequency compensated by the determined clock rate correction.

Disclosed are techniques for handling of radio frequency (RF) front-end group delays for roundtrip time (RTT) estimation. In an aspect, a network node transmits first and second RTT measurement (RTTM) signals to a user equipment (UE) and receives first and second RTT response (RTTR) signals from the UE. The network node measures the transmission times of the RTTM signals and the reception times of the RTTR signals, and the UE measures the transmission times the RTTM signals and the transmission times of the RTTR signals. The group delays of the transmit/receive chains of the network node and the UE are determined for one set of transmit/receive chains based on the first RTTM signal and first RTTR signal. The group delays of the transmit/receive chain used for the second RTTM signal and the second RTTR signal are determined relative to the group delay of the one set of transmit/receive chains.

The present disclosure provides a method, performed by a user equipment (UE), of determining a propagation delay value, the method including requesting a propagation delay from a base station, transmitting a time measurement signal on a time measurement resource allocated by the base station, receiving, from the base station, a response including an extended timing advance (TA) command, and based on the received response, applying time information and starting a timer. The present disclosure provides a method, performed by a UE, of performing communication in an unlicensed spectrum, the method including determining whether to transmit data via a configured grant (CG), comparing priorities of the CG and an uplink resource, and changing the priority of the CG, based on a listen before talk (LBT) failure.

This application provides a downlink transmission method. A session management network element obtains duration, namely, a first delay, between an expected moment at which a downlink service packet arrives at an access network element and an estimated moment at which the downlink service packet arrives at the access network element, the expected moment is within a first scheduling window, and a next scheduling window adjacent to the first scheduling window is a downlink scheduling window. Then, the session management network element sends the first delay to an application network element, where the first delay is used by an application server to determine a second moment at which the downlink service packet is sent, and a moment at which the downlink service packet sent at the second moment arrives at the access network element is within the first scheduling window.

Techniques are provided for signaling timing error group (TEG) updates for positioning. An example for providing reference signal measurement values with a mobile device incudes measuring one or more reference signals, determining a timing error change associated with one or more reference signal measurement values, and transmitting the one or more reference signal measurement values and an indication of the timing error change.

High-frequency communications in 5G and especially 6G will require precise synchronization of user devices with the base station, including setting the user device clock time and clock rate. The base station can assist user devices by periodically providing a guard-space timestamp point, at which a phase or amplitude of the timing signal abruptly changes in the middle of the guard-space of a particular resource element or a particular OFDM symbol. A receiver can determine precisely the time of arrival of the timestamp point, and correct its clock setting to agree with the time of the timestamp point. The receiver can then provide uplink messages aligned with the base station's clock, by adding a previously determined timing advance to each uplink transmission. In addition, the user device can measure two guard-space timing signals with a predetermined separation, thereby adjusting the clock rate.

Systems and methods are disclosed herein that relate to determining Timing Advance (TA) value validity in a cellular communications system. In some embodiments, a method performed by a wireless device comprises measuring a reference time of arrival (TOA) value for a reference base station (BS) for a time T.sub.0 at which the wireless device has a valid timing advance, TA(T.sub.0), value, measuring TOA values for a set of other BSs for T.sub.0, and computing and storing time difference of arrival, TDOA.sub.X(T.sub.0), values for the other BSs for T.sub.0. The method further comprises measuring a reference TOA value for the reference BS for a time T.sub.1, measuring TOA values for the other BSs for T.sub.1, and computing time difference of arrival, TDOA.sub.X(T.sub.1), values for the other BSs for T.sub.1. The method further comprises determining whether the TA(T.sub.0) value is valid at T.sub.1 based on the TDOA.sub.X(T.sub.0) and TDOA.sub.X(T.sub.1) values.

An automation system has a master control unit, a first radio subscriber, a first radio device and a clock master. The first radio device has a first synchronization element, a first radio module and a first connection for the bus system. The first radio module can establish a radio connection to the first radio subscriber for data exchange with a bus system provided by the master control unit. The first radio connection has a first radio channel with a first frequency range. The first synchronization element is set up to output a synchronization signal to the first radio module, based on a signal received from the clock master via the first connection. The first radio module is set up to change a frequency of the first radio channel based on the synchronization signal, within the first frequency range, on the basis of a first hopping table.