Subband Switching for Unlicensed Spectrum Reliability

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Solution Overview

Problem

In 5G NR systems, the dynamic switch method for BWP is not applicable in standalone LAA scenarios due to unknown unoccupied BWPs, leading to potential collisions and congestion, and the uncertainty of Listen Before Talk (LBT) restricts the transmission of dynamic signaling and important system information.

Innovation Solution

A method where the base station switches UEs to K1 target subbands before the maximum channel occupy time expires, using orthogonal subbands for system information transmission, and dynamically indicates the end of MCOT to ensure continuous downlink transmission, while using K2 candidate subbands for UE-specific information to avoid collisions and ensure reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If dynamic BWP switching is used in 5G NR systems, then flexibility and timeliness of configuration are improved, but the method becomes inapplicable in standalone LAA scenarios due to unknown unoccupied BWPs

Engineering Contradiction:

Improveflexibility and timeliness of BWP configurationVSAvoidapplicability in standalone LAA scenarios

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system divides the frequency spectrum into multiple subbands, each capable of independent LBT and transmission. This segmentation allows the base station to identify unoccupied subbands independently and switch UEs to specific target subbands within the MCOT, making dynamic adaptation possible in LAA scenarios where complete BWP unoccupancy cannot be assumed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The system implements dynamic subband indication through physical layer signaling that specifies target subbands for UE transmission within the current MCOT. This dynamic mechanism allows real-time adaptation to channel conditions and LBT outcomes, enabling flexibility comparable to BWP switching while being applicable to LAA's partial occupancy scenario.

Inventive Principle:

Principle #15Dynamics

2Productivity

If multiple UEs are scheduled on unoccupied BWPs simultaneously, then system throughput is improved, but collisions and congestion occur without proper distribution

Engineering Contradiction:

Improvesystem throughputVSAvoidcollision avoidance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

Each UE is assigned specific target subbands indicated by the base station through signaling. This local quality assignment ensures that UEs transmit on different subbands rather than competing for the entire bandwidth, distributing load locally across multiple subbands and preventing collisions while maintaining high throughput.

Inventive Principle:

Principle #3Local quality

3Reliability

If Listen Before Talk is performed on multiple BWPs, then channel access reliability is improved, but the transmission of dynamic signaling and system information is restricted by MCOT

Engineering Contradiction:

Improvechannel access reliabilityVSAvoidtransmission time for signaling and system information

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The base station performs LBT on multiple subbands before the MCOT begins and identifies target subbands in advance. This preliminary action allows the base station to prepare and indicate target subbands to UEs through signaling within the MCOT, ensuring both reliable channel access and timely delivery of control information without exceeding MCOT limits.

Inventive Principle:

Principle #10Preliminary action

4Reliability

If all information is transmitted in a fixed frequency band, then UE detection reliability is improved, but transmission may fail due to LBT failure on that specific band

Engineering Contradiction:

ImproveUE detection reliabilityVSAvoidtransmission flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Instead of relying on a single fixed frequency band, the system uses multiple subbands as alternative dimensions for information transmission. The base station indicates target subbands through signaling, allowing UEs to detect information on the indicated subband within the MCOT. This multi-dimensional approach ensures detection reliability while providing flexibility to adapt to LBT outcomes on different subbands.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS11374722B2Method and device used in UE and base station for wireless communication

Publication Date: 2022.06.28 APOGEE NETWORKS LLC

AI summary

The disclosure provides a method and a device in a User Equipment (UE) and a base station for wireless communication. The UE receives a first signaling in a first time-frequency resource, and receives a first radio signal in a second time-frequency resource; the first signaling is used for indicating K1 target subband(s), the K1 target subband(s) comprise(s) K1 target time-frequency resource(s) respectively, and the second time-frequency resource is one of the K1 target time-frequency resource(s); the first signaling and the first radio signal are both specific to the UE; time domain resources occupied by the first time-frequency resource belong to a first time window. Through the design of the K1 target subband(s), the disclosure guarantees the transmission of important information such as system information and subband indicator signaling on unlicensed spectrum, thereby improving overall performances of the system.