Uplink Reference Signal Triggering for Unlicensed Spectrum Mobility

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Solution Overview

Problem

In wireless communication systems using unlicensed spectrum, the failure to transmit downlink reference signals due to occupied channels can lead to degraded mobility and handover performance, as devices lack a reference for measurements during handover operations.

Innovation Solution

An electronic device detects the absence of a downlink reference signal and initiates the transmission of an uplink reference signal based on predefined trigger criteria, allowing the network to maintain mobility and handover performance by notifying the base station, which can then perform actions such as reallocating frequencies or prolonging measurement gaps.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the base station applies Listen Before Talk (LBT) procedure in unlicensed spectrum, then channel access compliance is improved, but downlink reference signal transmission reliability deteriorates when channel is busy

Engineering Contradiction:

Improvechannel access complianceVSAvoiddownlink reference signal transmission reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

Instead of relying solely on downlink reference signals from the base station, the invention inverts the approach by having the electronic device transmit uplink reference signals to the base station. This allows the device to actively provide measurement references when downlink signals are blocked by LBT procedures, resolving the contradiction between channel access compliance and transmission reliability.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The invention introduces a notification mechanism as an intermediary between the electronic device and base station. When the device detects missing downlink reference signals, it sends a notification triggering uplink reference signal transmission. This intermediary communication channel ensures reliable reference signal availability regardless of downlink channel status.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-generated harmful factors

If the base station does not transmit downlink reference signals due to occupied channel, then channel collision is avoided, but mobility performance deteriorates due to lack of measurement reference

Engineering Contradiction:

Improvechannel collision avoidanceVSAvoidmobility performance

Core Design Contradiction:

Object-generated harmful factorsVSReliability

Solution Approach 1:

The invention reverses the traditional reference signal direction by implementing uplink reference signal transmission from electronic device to base station. This inversion ensures that mobility measurements can continue even when downlink channels are occupied, maintaining mobility performance while avoiding channel collisions through LBT compliance.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The electronic device serves itself by generating and transmitting uplink reference signals when downlink reference signals are unavailable. This self-service mechanism ensures continuous measurement capability without requiring successful downlink transmission, resolving the contradiction between collision avoidance and mobility performance.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If the electronic device monitors for downlink reference signals continuously, then detection accuracy is improved, but energy consumption increases

Engineering Contradiction:

Improvedownlink reference signal detection accuracyVSAvoidenergy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

Instead of continuous monitoring, the invention implements partial action by triggering uplink reference signal transmission only when downlink reference signals are detected as missing. This selective approach maintains detection accuracy for triggering decisions while reducing overall energy consumption by avoiding continuous transmission and processing.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The invention employs periodic action through measurement gaps where the device monitors for downlink reference signals at specific intervals rather than continuously. This periodic monitoring maintains sufficient detection accuracy for handover decisions while significantly reducing energy consumption compared to continuous monitoring.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS11665570B2Method and system for triggering an uplink reference signal transmission

Publication Date: 2023.05.30 SONY GROUP CORP

AI summary

An electronic device (14) detects when a downlink reference signal has not been received from a base station (12), and initiates transmission of an uplink reference signal (64) in response to determining that certain trigger criteria have been satisfied. Upon receiving the uplink reference signal (64) or a notification signal (60) from the electronic device (14), the base station (12) can perform various actions to maintain network mobility and handover performance. In this manner, the disclosed approach allows a network to maintain mobility and handover performance even when a base station (12) is unable to transmit downlink reference signals due to an occupied communication channel.