Low Latency Beam Selection for TCI State Switching

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Solution Overview

Problem

Current methods for controlling Transmission Configuration Indicator (TCI) states in next-generation mobile communication systems, such as NR, require a relatively long time to change, leading to potential communication throughput reductions due to frequent changes.

Innovation Solution

Implementing a method for low latency beam selection that allows the user terminal to switch TCI states or beams without configuring a TCI state, using higher layer signaling to assume a common beam for multiple channels, thereby reducing communication overhead and latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a TCI state control method is implemented in NR to control channel transmission/reception processing, then the communication system can manage beamforming and channel characteristics, but the TCI state change requires relatively long time and creates communication overhead, leading to reduced communication throughput when frequent changes are needed

Engineering Contradiction:
ImproveTCI state control accuracyVSAvoidTCI state change time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The base station performs beam measurement and determines the optimal TCI state in advance before the actual TCI state change is needed. By preparing the TCI state information beforehand and storing it in the terminal, the system eliminates the time delay associated with real-time TCI state changes, allowing immediate switching when required without affecting communication throughput

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The TCI state control process is divided into separate stages: beam measurement stage, TCI state determination stage, and TCI state application stage. This segmentation allows each stage to be optimized independently, with the measurement and determination phases occurring in advance while the actual state change can be executed rapidly when needed

Inventive Principle:
Principle #1Segmentation

2Reliability

If a TCI state control method is implemented in NR to control channel transmission/reception processing, then the communication system can manage beamforming and channel characteristics, but communication overhead increases, leading to reduced communication throughput when frequent changes are needed

Engineering Contradiction:
ImproveTCI state control accuracyVSAvoidcommunication overhead
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The base station determines and notifies the terminal of the TCI state in advance through higher layer signaling before the TCI state change is executed. This preliminary notification reduces the need for frequent real-time signaling exchanges, thereby reducing communication overhead while maintaining accurate TCI state control for beamforming management

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The TCI state determination and measurement functions are extracted from the real-time communication path and performed in advance by the base station. By separating the measurement and decision-making processes from the actual data transmission path, the system minimizes the signaling overhead required during frequent TCI state changes

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If traditional TCI state control methods are used, then channel transmission/reception can be controlled, but the system cannot switch TCI states or beams at high speed, limiting communication throughput during frequent state changes

Engineering Contradiction:
Improvechannel control capabilityVSAvoidbeam switching speed
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The terminal stores multiple TCI state candidates in advance based on base station measurements and notifications. When a TCI state change is required, the terminal can immediately switch to the pre-determined state without performing new measurements or waiting for additional signaling, thereby achieving high-speed beam switching while maintaining reliable channel control

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements dynamic TCI state switching by maintaining multiple pre-configured TCI state candidates that can be rapidly activated based on communication conditions. This dynamic approach allows the system to adapt beam directions quickly in response to changing channel conditions while preserving the reliability of channel control through the base station's coordinated management

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3823337B1User equipment and base station
Publication Date: 2024.02.21 NTT DOCOMO INC
  • EP3823337B1 patent drawingFigure 1
  • EP3823337B1 patent drawingFigure 2
  • EP3823337B1 patent drawingFigure 3

AI summary

A user terminal according to one aspect of the present disclosure includes: a receiving section that receives a Physical Downlink Control Channel (PDCCH); and a control section that, when low latency beam selection is configured by a higher layer signaling, assumes that a same spatial domain filter is used for transmission of the PDCCH and transmission and reception of a specific channel. According to one aspect of the present disclosure, it is possible to switch a TCI state or a beam of a channel at a high speed.