Multi-TRP Sidelink QCL Indication for CFO and Doppler Handling
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Solution Overview
Problem
Existing vehicle-to-everything (V2X) communications systems face challenges in efficiently sharing wireless communications resources, particularly in scenarios involving multiple transmission and reception points (TRPs) where carrier frequency offset (CFO) and Doppler shift/spread vary, leading to suboptimal signal processing and resource allocation.
Innovation Solution
The implementation of quasi-co-location (QCL) indication techniques for multi-TRP sidelink communications, where transmitting UEs determine and indicate QCL relationships between antenna ports of different TRPs, enabling receiving UEs to measure and confirm QCL assumptions based on CFO, Doppler shift, and delay characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-TRP sidelink communications are implemented without QCL indication, then system capacity and coverage are improved, but signal processing accuracy deteriorates due to varying CFO and Doppler shift across TRPs
Solution Approach 1:
The transmitting UE determines QCL relationships between antenna ports of different TRPs in advance and includes this information in SCI messages before actual data transmission. This preliminary indication allows the receiving UE to prepare appropriate reception parameters, resolving the contradiction by establishing accurate signal processing expectations before the signal arrives, thus maintaining measurement precision while enabling multi-TRP communications that improve system capacity.
2Measurement precision
If QCL indication is added to SCI messages for multi-TRP communications, then signal processing accuracy is improved, but message overhead and complexity increase
Solution Approach 1:
The QCL indication mechanism applies differentiated information provision based on local conditions: the transmitting UE determines QCL relationships specific to each pair of antenna ports and TRPs, and includes targeted QCL indication information in SCI messages only when multi-TRP transmission is configured. This localized approach provides necessary precision information without universally increasing message complexity for all transmissions, thus improving measurement precision while controlling device complexity.
3Productivity
If receiving UEs measure reference signals from multiple TRPs individually, then resource allocation efficiency is improved, but processing time and complexity increase
Solution Approach 1:
The receiving UE uses the QCL indication information received in advance from the transmitting UE to pre-configure measurement expectations and parameters for multiple TRPs. This allows the receiving UE to efficiently process reference signals from multiple TRPs by having predetermined QCL assumptions, reducing the time and complexity of real-time measurements while improving resource allocation efficiency through better-informed reception decisions.
Data Source
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AI summary
A method of wireless communication by a transmitting sidelink user equipment (UE) determines at least one quasi-co-location (QCL) relationship between antenna ports of the transmitting sidelink UE. The QCL relationship corresponds to carrier frequency offset (CFO), average delay, delay spread, Doppler shift, and/or Doppler spread across the antenna ports of the transmitting sidelink UE. Each port maps to a different transmission and reception point (TRP). The method also indicates the QCL relationship(s) to a receiving sidelink UE. A method of wireless communication by a receiving sidelink UE receives a message from TRPs of a transmitting sidelink UE. The message indicates a QCL assumption for the TRPs. The method also individually measures reference signals received from each transmission port of the TRPs. The method may also determine whether signaling from the TRPs satisfies all conditions for the QCL assumption, and report to the transmitting sidelink UE a result of the determining.