User Terminal QCL Determination for Multi-TRP Downlink
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Solution Overview
Problem
In next-generation mobile communication systems, specifically in NR, the existing specifications do not adequately support the use of multiple panels/TRPs, leading to inadequate control of quasi-co-location assumptions, which limits spatial diversity gain and communication throughput.
Innovation Solution
A user terminal is equipped with a receiving section for downlink shared channels and a control section that determines the number of default Quasi-Co-Locations (QCLs) based on downlink control information, enabling effective communication even with multiple panels/TRPs by managing QCL assumptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If existing NR specifications are followed, then device complexity is reduced, but spatial diversity gain and communication throughput cannot be implemented
Solution Approach 1:
The patent changes the parameter of QCL assumption by introducing a new default QCL assumption mechanism specifically for multi-TRP scenarios. When DCI format 1_1 is used without a TCI field, the system defaults to assuming two QCLs instead of one, enabling spatial diversity without requiring complex configuration changes to existing devices.
Solution Approach 2:
The system enables self-service by allowing the UE to automatically determine the number of QCLs based on the DCI format received. The UE itself decides whether to apply one or two default QCLs based on whether DCI format 1_1 with or without TCI field is used, eliminating the need for complex external configuration.
2Reliability
If multiple panels/TRPs are used, then spatial diversity gain is improved, but QCL assumption control becomes inadequate
Solution Approach 1:
The patent modifies the QCL assumption parameter by establishing a default of two QCLs for DCI format 1_1 without TCI field. This parameter change enables the system to automatically support multiple panels/TRPs operation, improving spatial diversity gain while maintaining ease of operation through automatic determination.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the default QCL assumption behavior before actual communication occurs. The UE is pre-instructed to assume two QCLs when receiving DCI format 1_1 without TCI field, so that when multiple panels/TRPs are used, the correct QCL control is already in place without requiring real-time configuration.
3Ease of operation
If DCI format 1_1 without TCI field is used, then ease of operation is improved, but number of QCLs cannot be appropriately controlled
Solution Approach 1:
The patent resolves this contradiction by changing the default QCL parameter based on the DCI format type. When DCI format 1_1 without TCI field is used (simple format), the system automatically sets the default number of QCLs to two, maintaining both ease of operation and QCL assumption accuracy through format-based parameter selection.
Data Source
AI summary
A user terminal according to an aspect of the present disclosure includes: a receiving section that receives a downlink shared channel (Physical Downlink Shared Channel (PDSCH)), based on one piece of downlink control information; and a control section that determines a number of default Quasi-Co-Locations (QCLs) to be applied to the PDSCH, based on the downlink control information. According to an aspect of the present disclosure, DL communication can be preferably carried out even in a case where multiple panels/TRPs are used.