UE Uplink Mode Switching for Unlicensed Spectrum LBT

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Solution Overview

Problem

In wireless communication systems, especially on Unlicensed Spectrum, non-codebook-based uplink transmissions are hindered by Listen Before Talk (LBT), leading to instability and failure in channel estimation and feedback, as the transmission of downlink reference signals cannot be guaranteed, preventing User Equipment (UE) from operating in non-codebook-based mode.

Innovation Solution

A method where the User Equipment (UE) receives signaling with a field indicating whether the transmission is non-codebook-based or codebook-based, allowing flexible switching between modes, and uses this information to determine the precoding matrix for uplink reference signals, enabling operation even when downlink reference signals are not received.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If non-codebook-based uplink transmission is used, then precoding accuracy is improved, but transmission reliability deteriorates due to LBT blocking downlink reference signals

Engineering Contradiction:

Improveprecoding accuracyVSAvoidtransmission reliability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent changes the transmission mode parameter from non-codebook-based to codebook-based precoding when downlink reference signals are blocked by LBT, allowing the system to adapt between different precoding modes based on channel conditions and LBT status

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The system dynamically switches between non-codebook-based and codebook-based uplink transmission modes based on whether downlink reference signals are successfully received, making the transmission mode flexible rather than fixed

Inventive Principle:

Principle #15Dynamics

2Stability of the object's composition

If codebook-based precoding is used, then transmission stability is improved, but signaling overhead increases due to channel state information feedback

Engineering Contradiction:

Improvetransmission stabilityVSAvoidsignaling overhead

Core Design Contradiction:

Stability of the object's compositionVSLoss of information

Solution Approach 1:

The system uses codebook-based precoding with partial channel state information feedback when stability is needed, rather than full feedback, reducing signaling overhead while maintaining adequate transmission stability

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent makes the uplink transmission system universal by supporting both codebook-based and non-codebook-based modes, allowing the same system to handle different scenarios (overhead-sensitive vs. stability-sensitive) with different precoding approaches

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Manufacturing precision

If UE operates in non-codebook-based mode, then precoding performance is improved, but adaptability deteriorates when downlink reference signals are blocked

Engineering Contradiction:

Improveprecoding performanceVSAvoidmode adaptability

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The system dynamically adapts between non-codebook-based and codebook-based transmission modes based on LBT outcomes and downlink reference signal reception status, making the UE adaptable to different channel conditions and spectrum access scenarios

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the transmission mode parameter based on channel conditions and LBT status, allowing the UE to switch between non-codebook-based (when downlink signals are available) and codebook-based (when downlink signals are blocked) modes

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11336411B2Method and device in UE and base station used for wireless communication

Publication Date: 2022.05.17 APOGEE NETWORKS LLC

AI summary

The present disclosure provides a method and a device in a User Equipment (UE) and a base station for wireless communications. The UE receives a first signaling, and then transmits a first radio signal in a first subband. The first signaling comprises scheduling information of the first radio signal; the first signaling comprises a first field, the first field in the first signaling being used for determining a first reference-signal-resource group or the first subband, the first reference-signal-resource group comprising K1 first-type reference signal resource(s); whether the scheduling information of the first radio signal is non-codebook-based or codebook-based is related to the first field in the first signaling; the first subband is one of M subbands. The above method allows UE to flexibly switch between non-codebook-based and codebook-based uplink transmissions, thus avoiding the problem that a single uplink transmission mode cannot work on Unlicensed Spectrum.