Default Search Space Set for 5G NR PDCCH Monitoring

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Solution Overview

Problem

In 5G NR communication systems, there is a challenge in efficiently switching between groups of search space sets for PDCCH monitoring, particularly during non-monitoring time periods, which can lead to undefined UE behavior and misalignment between the UE and gNB, affecting channel occupancy status detection and control information transmission.

Innovation Solution

Implementing a default search space set for PDCCH monitoring, allowing the UE to revert to this default set after non-monitoring periods, ensuring consistent monitoring functionality regardless of explicit or implicit SSS group switching instructions, and synchronizing with the gNB's channel occupancy status.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the UE switches between groups of search space sets based on explicit or implicit instructions, then the adaptability of PDCCH monitoring is improved, but the reliability of monitoring during non-monitoring time periods deteriorates due to undefined UE behavior

Engineering Contradiction:

Improveadaptability of PDCCH monitoringVSAvoidreliability of monitoring during non-monitoring time periods

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-configuring a default search space set group that the UE automatically reverts to after non-monitoring time periods. This default configuration is established in advance through RRC signaling, ensuring that the UE has a predetermined fallback state ready before any monitoring interruptions occur, thereby eliminating undefined behavior during transitions.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback mechanisms where the gNB provides explicit indications to the UE about which search space set group to use, and the UE provides feedback through HARQ acknowledgments. This closed-loop feedback ensures that both gNB and UE maintain aligned understanding of the active search space set group, preventing misalignment during switching transitions.

Inventive Principle:

Principle #23Feedback

2Reliability

If the UE monitors PDCCH continuously, then the reliability of control information reception is improved, but the energy consumption increases during non-monitoring time periods

Engineering Contradiction:

Improvereliability of control information receptionVSAvoidenergy consumption during non-monitoring time periods

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies periodic action by implementing discontinuous reception (DRX) cycles where the UE alternates between monitoring and non-monitoring periods. During non-monitoring periods, the UE suspends PDCCH monitoring to conserve energy, and automatically reverts to the default search space set group when monitoring resumes, ensuring reliable control information reception without continuous energy consumption.

Inventive Principle:

Principle #19Periodic action

3Adaptability or versatility

If multiple search space set groups are configured for different channel occupancy scenarios, then the adaptability to unlicensed spectrum operations is improved, but the device complexity increases

Engineering Contradiction:

Improveadaptability to unlicensed spectrum operationsVSAvoiddevice complexity of search space management

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies segmentation by dividing search space sets into multiple distinct groups (first group and second group), each optimized for specific channel occupancy scenarios. The gNB configures these groups separately through RRC signaling, and the UE switches between them based on gNB indications or default rules, making the complexity manageable through structured organization rather than monolithic configuration.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS12137465B2User equipment and base station involved in control channel signaling

Publication Date: 2024.11.05 PANASONIC INTELLECTUAL PROPERTY CORP OF AMERICA

AI summary

The present disclosure relates to a user equipment (UE) that comprises a processor that operates a monitoring function that involves monitoring of a downlink control channel of an unlicensed radio cell based on one of a plurality of groups of search space sets (SSS). The unlicensed radio cell operates in an unlicensed spectrum and is controlled by a base station that is in communication with the user equipment. Further, one of the plurality of groups of SSSs is configured to be a default group of SSSs. The processor determines one group of the plurality of SSS groups for performing the monitoring function, depending on the downlink control channel. The monitoring function is not performed during a non-monitoring time period. The processor determines to perform the monitoring function based on the default group of SSSs, when performing the monitoring function subsequent to the non-monitoring time period.