WTRU CQI Reporting During Handover

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Solution Overview

Problem

Existing 3GPP Release 6 specifications do not provide optimal support for Modulation Coding Scheme (MCS) selection and scheduling for the High Speed Downlink Shared Channel (HS-DSCH) in the new serving cell after a handover occurs, leading to inefficient resource utilization and potential decoding issues for the wireless transmit/receive unit (WTRU).

Innovation Solution

A method implemented in a WTRU to transmit channel quality indication (CQI) reports to a handover target Node B until a stop condition is reached, allowing the target Node B to quickly adapt to new channel conditions and determine optimal transmission rates and scheduling before initiating data transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If CQI reports are transmitted continuously after handover, then the target Node B can quickly adapt to new channel conditions, but the signaling overhead and resource consumption increase

Engineering Contradiction:

ImproveAdaptation speed to new channel conditionsVSAvoidSignaling overhead and resource consumption

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The patent implements periodic CQI reporting where the WTRU transmits CQI reports at regular intervals (e.g., every 10ms or 20ms) after handover instead of continuously. This periodic transmission maintains adequate channel quality feedback for the target Node B to adapt transmission parameters while significantly reducing signaling overhead and resource consumption compared to continuous reporting.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent sends CQI reports before the handover is complete and during the initial period after handover. This preliminary action ensures the target Node B has channel quality information available before data transmission begins, enabling faster adaptation without requiring continuous post-handover reporting.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If CQI reports are transmitted frequently after handover, then optimal MCS selection is achieved, but the processing complexity and delay increase

Engineering Contradiction:

ImproveChannel quality measurement accuracyVSAvoidProcessing complexity and reporting delay

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent employs periodic CQI reporting with configured intervals that balance measurement accuracy needs with processing complexity. By reporting at regular intervals rather than continuously or on every transmission opportunity, the system achieves sufficient channel quality measurement accuracy for optimal MCS selection while reducing the processing burden on both WTRU and Node B.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent allows dynamic adjustment of CQI reporting parameters such as reporting interval and frequency based on channel conditions and traffic requirements. When channel conditions change rapidly, more frequent reporting is triggered; when conditions are stable, reporting interval increases, thus adapting measurement precision to actual needs and reducing unnecessary processing complexity.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the target Node B waits for CQI reports before transmitting data, then transmission reliability improves, but the handover completion time increases

Engineering Contradiction:

ImproveTransmission reliabilityVSAvoidHandover completion time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent transmits CQI reports before the handover is fully complete and during the initial data transmission phase. This preliminary action ensures the target Node B receives channel quality information in advance, enabling reliable MCS selection and data transmission without requiring the Node B to wait for post-handover CQI reports, thus maintaining transmission reliability while minimizing handover completion time.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent ensures continuous CQI feedback during the handover transition and initial data transmission phase. By maintaining CQI reporting continuity through handover rather than interrupting it, the system provides uninterrupted channel quality information to the target Node B, enabling continuous adaptive transmission and avoiding delays that would result from waiting for CQI reports after handover completion.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS20250203644A1Determining and sending channel quality indicators (CQIS) for different cells

Publication Date: 2025.06.19 INTERDIGITAL PATENT HOLDINGS INC

AI summary

A wireless transmit/receive unit (WTRU) may periodically transmit control information in slots. The control information may include channel quality indicators (CQIs) for a plurality of cells. In response to expiration of a timer for a first cell of the plurality of cells or in response to a received layer 2 (L2) message associated with the first cell, the transmission of the control information including the CQIs may be ceased for the first cell and the periodic transmission of the control information may continue for a second cell of the plurality of cells.