HARQ Timing Design for TDD Systems

Solution Overview

Problem

In LTE networks, dynamic changes in TDD UL/DL configurations between consecutive radio frames can decrease throughput and cause delays in the HARQ process, making it challenging for user equipment (UE) to identify and adapt to these changes, thereby affecting data transmission efficiency.

Innovation Solution

The method involves identifying a reference TDD UL/DL configuration based on indications received for two consecutive radio frames, allowing the UE to adjust HARQ timing accordingly, using DCI messages transmitted in specific subframes to inform the UE of configuration changes and enabling timely data and acknowledgement signal transmissions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If dynamic TDD UL/DL reconfiguration is implemented to adapt to varying traffic conditions, then system adaptability is improved, but HARQ process timing is extended and throughput decreases

Engineering Contradiction:

ImproveTDD configuration adaptabilityVSAvoidHARQ process throughput

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent applies preliminary action by determining the TDD UL/DL configuration for the second radio frame in advance, before the HARQ process begins. The eNB configures and signals the TDD configuration pattern to the UE beforehand, allowing the UE to pre-determine HARQ timing based on the known configuration. This eliminates delays caused by real-time configuration changes during the HARQ process, thereby maintaining high throughput while enabling dynamic reconfiguration.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamics by introducing a dynamic TDD UL/DL reconfiguration mechanism where the eNB can change TDD configurations between radio frames based on traffic conditions. The system dynamically selects from multiple predefined TDD configuration patterns (0-6) and signals the chosen pattern to the UE. This allows the system to adapt to varying uplink/downlink traffic demands while maintaining deterministic HARQ timing within each configured frame.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If TDD UL/DL configuration changes between consecutive radio frames, then traffic handling flexibility is improved, but HARQ timing identification becomes complex and error-prone

Engineering Contradiction:

ImproveTraffic configuration flexibilityVSAvoidHARQ timing identification complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies dynamics by enabling the eNB to dynamically signal TDD configuration patterns to the UE for each radio frame. The UE receives the configuration pattern indicator and uses it to determine the appropriate TDD UL/DL configuration, which then guides HARQ timing identification. This dynamic approach allows flexible traffic handling while maintaining systematic and error-free timing identification through explicit signaling.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback by having the eNB explicitly signal the TDD configuration pattern to the UE through downlink control information. The UE uses this feedback to correctly identify HARQ timing based on the signaled configuration. This feedback mechanism ensures that both eNB and UE have consistent understanding of the current TDD configuration, eliminating timing identification errors that would arise from autonomous or implicit configuration determination.

Inventive Principle:

Principle #23Feedback

3Productivity

If real-time TDD configuration changes are made to optimize network performance, then network adaptability is improved, but data transmission throughput decreases due to extended HARQ delays

Engineering Contradiction:

ImproveNetwork performance optimizationVSAvoidHARQ process delay

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by determining the TDD UL/DL configuration for the second radio frame in advance, before the HARQ process begins. The eNB configures and signals the TDD configuration pattern to the UE beforehand, allowing the UE to pre-determine HARQ timing based on the known configuration. This eliminates delays caused by real-time configuration changes during the HARQ process, thereby maintaining high throughput while enabling dynamic reconfiguration.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9331759B2HARQ timing design for a TDD system

Publication Date: 2016.05.03 APPLE INC

AI summary

Disclosed are methods and apparatuses related to receiving one or more indications of time division duplex (TDD) uplink/downlink (UL/DL) configurations for two consecutive radio frames. Based on the indications of the TDD UL/DL configurations, a reference TDD UL/DL configuration may be identified for one or more Hybrid Automatic Repeat reQuest (HARQ) processes.