SMF Latency Calculation for TSN-3GPP Interworking
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Solution Overview
Problem
Determining the accumulated latency of transmission between a terminal device (UE) and a UPF network element in a 3GPP network when interworking with a Time Sensitive Network (TSN) is a technical challenge, as existing methods require clock synchronization between all nodes, which is complex and difficult to implement.
Innovation Solution
The method involves the SMF network element calculating the second latency by summing the first latency from the TSN to the UPF and the third latency from the UPF to the UE, using PCC rules to determine the maximum transmission latency, thereby simplifying the calculation of accumulated latency without the need for extensive clock synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If clock synchronization is implemented between all nodes in the 3GPP and TSN network, then the accumulated latency can be accurately measured, but the system complexity and implementation difficulty increase significantly
Solution Approach 1:
The patent segments the latency measurement process into two independent parts: TSN network latency (first latency) and 3GPP network latency (third latency). Each part is measured separately using different methods appropriate to each network type, avoiding the need for complex end-to-end clock synchronization across heterogeneous networks. The SMF then combines these segmented measurements to determine the total accumulated latency.
Solution Approach 2:
The UPF network element acts as an intermediary that receives the first latency information from the TSN network and forwards it to the SMF. The SMF then acts as another intermediary that combines this with the third latency (determined via PCC rules) to calculate the second latency. This intermediary approach allows latency measurement without requiring direct clock synchronization between all end nodes.
2Measurement precision
If clock synchronization is implemented between all nodes, then the accumulated latency can be determined, but the implementation becomes difficult and complex
Solution Approach 1:
The measurement process is segmented into network-specific components that can be implemented independently. The TSN network measures latency using TSN-standard methods, while the 3GPP network uses PCC rules for QoS-based latency determination. This segmentation makes implementation easier by allowing each network domain to use its own established mechanisms rather than requiring a new complex synchronization system.
Solution Approach 2:
Each network domain (TSN and 3GPP) performs latency measurement independently using its own native mechanisms. The TSN network self-measures its contribution to total latency, and the 3GPP network self-determines its latency component through PCC rules. This self-service approach simplifies implementation by leveraging existing network capabilities rather than requiring external synchronization infrastructure.
3Device complexity
If the third latency is determined using PCC rules, then the accumulated latency calculation is simplified, but the precision may be affected by QoS policy variations
Solution Approach 1:
The patent changes the measurement parameter from direct physical clock synchronization to QoS-based latency values defined by PCC rules. Instead of measuring time directly through synchronized clocks, the system uses QoS parameters (such as packet delay budget) that are already part of the 3GPP network's policy framework. This parameter change simplifies the system by using existing QoS mechanisms while providing sufficiently precise latency information for TSN interworking.
Data Source
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AI summary
This application provides a communication method and a communications apparatus. In the communication method, an SMF network element determines, according to a PCC rule of a flow, a third latency of transmitting the flow from a UPF network element to UE, so that a second latency of transmitting the flow from a flow service provider in a TSN to the UE can be determined based on the third latency and a first latency of transmitting the flow from the flow service provider in the TSN to the UPF network element. The communication method and the communications apparatus provided in this application use a relatively simple implementation to determine an accumulated latency of transmitting the flow from the UPF network element to the UE, that is, use a relatively simple manner to determine an accumulated latency of transmitting the flow from the flow service provider in the TSN to the UE.