Network Clock Synchronization for Roaming Time-Sensitive Communication
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Solution Overview
Problem
In 5G communication systems, clock skew due to time zone differences or different master clocks between home and visited public land mobile networks (HPLMN and VPLMN) leads to inaccurate time control in time-sensitive communication, affecting data flow accuracy in roaming scenarios.
Innovation Solution
A method for ascertaining the time difference between system clocks of different networks and transmitting this information to control-plane network nodes to determine accurate time parameters, independent of specific Protocol Data Unit sessions, ensuring precise clock synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the V-SMF provides TSCAI to the RAN based on the H-SMF's generation process, then the RAN can perform time control on data flow, but clock skew between HPLMN and VPLMN causes inaccurate time parameters
Solution Approach 1:
The patent introduces a time difference compensation mechanism as an intermediary between the H-SMF and V-SMF. The V-SMF obtains the time difference between HPLMN and VPLMN system clocks and uses this compensation value to adjust the TSCAI parameters before providing them to the RAN. This intermediary compensation mechanism resolves the clock skew issue caused by direct H-SMF to V-SMF time parameter transmission.
2Adaptability or versatility
If different master clocks are used by HPLMN and VPLMN, then each network can operate independently, but time zone differences and different master clocks cause clock skew and inaccurate time synchronization
Solution Approach 1:
The patent changes the time parameter representation by introducing a time difference compensation value. Instead of directly transmitting time parameters generated by the H-SMF, the V-SMF adjusts these parameters by adding the time difference between HPLMN and VPLMN system clocks. This parameter transformation allows each network to maintain its independent master clock while achieving accurate time synchronization.
3Device complexity
If the V-SMF directly uses H-SMF generated TSCAI without time difference compensation, then the process is simple, but the time control accuracy deteriorates due to clock skew
Solution Approach 1:
The patent applies preliminary action by having the V-SMF obtain and calculate the time difference between HPLMN and VPLMN system clocks before providing TSCAI to the RAN. This preliminary time difference compensation ensures that the time parameters are accurate from the start, avoiding the need for complex post-processing or iterative adjustments.
Data Source
AI summary
A user-plane network node and a method for clock synchronization are provided. The method includes determining, with processing circuitry of the user-plane network node, a time difference between a system clock of an external network of the user-plane network node and a system clock of a network to which the user-plane network node belongs. The method includes transmitting, to a control-plane network node, information including the time difference. The time difference is used by the control-plane network node to determine a time parameter of the system clock of the network to which the user-plane network node belongs. The time parameter is time-sensitive communication assistance information. The transmitting the information is independent of a particular Protocol Data Unit (PDU) session.