Multi-TRP QCL Control for PDSCH Reception in NR Terminals
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Solution Overview
Problem
Existing NR specifications do not adequately account for multiple panels/TRPs, leading to inadequate determination of QCL parameters, which can result in degraded system performance such as decreased throughput.
Innovation Solution
A method for determining QCL parameters for multiple panels/TRPs by using TCI states and QCL assumptions, including higher layer signaling, MAC CE, and DCI to configure and activate TCI states for PDCCH and PDSCH, with default QCL assumptions based on CORESETs and time duration thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a terminal camps on a cell with a small downlink reception level, then the terminal can maintain connection in weak signal areas, but uplink transmission quality deteriorates due to path loss
Solution Approach 1:
The patent changes the parameter of reference signal selection by switching from downlink-based reference signals (CSI-RS, CRS) to uplink-based reference signals (SRS). This parameter change allows the network to accurately measure uplink channel quality even when the terminal is camped on a cell with poor downlink signal, thereby resolving the contradiction between maintaining connection in weak signal areas and ensuring uplink transmission quality.
2Reliability
If downlink reference signals are used for channel quality measurement, then the measurement can be performed in weak signal conditions, but the measurement accuracy deteriorates due to downlink-uplink asymmetry
Solution Approach 1:
The patent inverts the traditional approach by using uplink reference signals instead of downlink reference signals for channel quality measurement. Since uplink and downlink channels are reciprocal in TDD systems, measuring the uplink channel provides accurate information about the downlink channel quality, thereby resolving the contradiction between measurement capability in weak signal conditions and measurement accuracy.
3Reliability
If the terminal reports channel quality based on downlink reference signals, then reporting can be performed in weak signal areas, but the reported quality does not reflect actual uplink conditions
Solution Approach 1:
The patent replaces the mechanical system of downlink reference signal measurement with an electromagnetic field-based uplink reference signal measurement. By using SRS (Sounding Reference Signal) in the uplink, the system directly measures the actual uplink channel conditions, thereby eliminating the information loss that occurs when downlink measurements are used to infer uplink quality.
Data Source
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Figure 2A~2D
Figure 3A~3B
AI summary
A terminal according to one aspect of the present disclosure includes: a reception section that receives at least one of one downlink control information and a plurality of pieces of downlink control information, the one downlink control information being used to schedule a plurality of Physical Downlink Shared Channels (PDSCHs), and the plurality of pieces of downlink control information being respectively used to schedule the plurality of PDSCHs; and a control section that controls the reception of the plurality of PDSCHs in a given duration based on one of quasi-co-location associated with a first control resource set for the one downlink control information, and quasi-co-location associated with a second control resource set for the plurality of pieces of downlink control information.