PT-RS Mapping for Correct Multi-TRP URLLC Signal Density
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Solution Overview
Problem
The existing NR R15 PT-RS mapping scheme for multi-TRP transmission in URLLC fails to ensure that each TRP has the correct density of phase-tracking reference signals, particularly in single-DCI based URLLC schemes, due to differing RF chains and resource allocation patterns.
Innovation Solution
A method for PT-RS mapping in single-DCI based URLLC schemes that ensures each TRP receives the correct density of PT-RS by frequency division multiplexing sets of PT-RSs associated with different TCI states, determined by the total number or minimum/maximum number of resource blocks or by individual allocation for each TRP, and time division multiplexing PT-RSs in different symbol sets based on DCI indications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a unified PT-RS mapping scheme is used for multi-TRP transmission, then the system complexity is reduced, but the phase-tracking reference signal density for each individual TRP cannot be ensured
Solution Approach 1:
The patent segments the PT-RS mapping into separate configurations for different TRPs. Each TRP (first and second TCI states) has its own PT-RS density parameters and resource block allocations, allowing independent optimization of phase-tracking reference signal density for each transmit point while maintaining overall system manageability through structured resource division.
2Measurement precision
If separate PT-RS configurations are used for each TRP, then the correct PT-RS density for each TRP is ensured, but the system complexity increases
Solution Approach 1:
The patent merges the separate PT-RS configurations for multiple TRPs into a unified resource block structure. By combining first and second resource block sets with their respective PT-RS mappings into a coordinated framework managed by single-DCI, the system achieves both individual TRP optimization and overall structural efficiency, reducing the burden on higher-layer signaling.
3Reliability
If frequency division multiplexing is applied to PT-RS for different TRPs, then interference between TRPs is reduced, but the resource allocation complexity increases
Solution Approach 1:
The patent applies local quality by assigning different PT-RS frequency densities to different resource block sets associated with different TRPs. The first resource block set uses a first frequency density while the second resource block set uses a second frequency density, allowing each TRP to have optimized phase-tracking reference signal characteristics tailored to its specific channel conditions and requirements.
Data Source
AI summary
Embodiments of the present disclosure are directed to methods and apparatuses for PT-RS mapping. In an embodiment of the present disclosure, the method includes transmitting a first set of phase-tracking reference signals in a first plurality of subcarriers within a first resource block set associated with a first TCI state with a first frequency density; transmitting a second set of phase-tracking reference signals in a second plurality of subcarriers within a second resource block set associated with a second TCI state with a second frequency density, where the first resource block set and the second resource block set are frequency division multiplexed in a time interval and a third resource block set composed of the first resource block set and the second resource block set is scheduled by a DCI.