SRS-TRS Association for Doppler Shift Pre-compensation
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Solution Overview
Problem
High-speed train scenarios with Single Frequency Network (SFN) deployments face significant performance degradation due to high Doppler shifts caused by high speeds and frequencies, leading to varying Doppler shifts experienced by User Equipments (UEs) from different Transmission and Reception Points (TRPs), which existing technologies fail to effectively pre-compensate for.
Innovation Solution
The method involves implicitly reporting Doppler shifts by associating Sounding Reference Signal (SRS) resources with Tracking Reference Signal (TRS) resources, allowing TRPs to pre-compensate for Doppler shifts by transmitting SRS with the same frequency as the receive frequency of the TRS, thereby enabling consistent signal transmission across multiple TRPs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Doppler shift pre-compensation is enabled at TRP side for SFN-based DL transmission, then communication performance is improved, but device complexity increases due to additional frequency adjustment mechanisms
Solution Approach 1:
The UE autonomously determines the SRS transmit frequency based on the received TRS frequency, without requiring explicit Doppler shift feedback or complex processing at the gNB side. The UE simply transmits SRS at the same frequency it received TRS, enabling self-service frequency adjustment that simplifies the overall system complexity while maintaining communication performance.
2Reliability
If SRS is transmitted with the same frequency as TRS receive frequency, then Doppler shift pre-compensation is achieved, but measurement precision requirements increase
Solution Approach 1:
The TRS acts as an intermediary signal that carries frequency information. Instead of requiring the UE to directly measure and report Doppler shift with high precision, the TRS provides a reference signal that the UE can simply copy to its SRS transmission frequency. This intermediary approach reduces the direct measurement precision burden on the UE while achieving accurate Doppler compensation at the gNB side.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively pre-compensates for Doppler shifts, improving communication performance by ensuring consistent signal reception and transmission across multiple TRPs, reducing performance degradation in high-speed train SFN deployments.
Implementation Method 1
The significant difference of the Doppler shifts experienced simultaneously by the UE will cause great performance degradation. One important enhancement method is to enable Doppler shift pre-compensation at TRP side (i.e. at gNB side) for SFN-based DL transmission so that UE will not experience significant different Doppler shifts from different TRPs.
Data Source
AI summary
Methods and apparatuses for implicitly reporting Doppler shift are disclosed. A method comprises receiving a configuration that indicates a TRS resource associated with a SRS resource for Doppler shift reporting; and transmitting the SRS resource, with a transmit frequency that is the same as a receive frequency of the TRS resource.