HARQ Timing Selection for TDD Carrier Aggregation

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Solution Overview

Problem

The limitations of the 3GPP LTE-A Release 10 standard in supporting TDD Component Carrier aggregation lead to restricted data throughput due to fixed uplink/downlink TDD configurations, causing conflicts in HARQ ACK/NACK signal scheduling across different TDD configurations in carrier aggregation scenarios.

Innovation Solution

A method for selecting a reference TDD configuration that aligns common uplink subframes between primary and secondary serving cells, allowing for flexible HARQ timing sequence alignment to resolve scheduling conflicts and enhance data transmission efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If TDD Component Carrier aggregation is limited to the same uplink/downlink TDD configurations, then design and operation within the standard is simplified, but data throughput is limited

Engineering Contradiction:

Improvedesign simplicityVSAvoiddata throughput

Core Design Contradiction:

Ease of manufactureVSProductivity

Solution Approach 1:

The patent changes the TDD configuration parameter from being fixed and identical across all component carriers to being selectable and configurable per carrier. This allows each component carrier to have optimized TDD configurations (different UL-DL ratios) based on traffic characteristics, thereby increasing data throughput while maintaining standard compatibility through controlled parameter variation

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If different TDD configurations are used for uplink and downlink traffic characteristics, then resource utilization flexibility is improved, but HARQ ACK/NACK signal scheduling conflicts occur

Engineering Contradiction:

Improveresource utilization flexibilityVSAvoidscheduling conflict

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent segments the HARQ-ACK feedback mechanism into carrier-specific scheduling. Each component carrier maintains its own HARQ timing relationships and ACK/NACK resource allocation independent of other carriers. This segmentation prevents scheduling conflicts by ensuring that different TDD configurations on different carriers do not interfere with each other's HARQ processes

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary layer of carrier-specific HARQ configuration that mediates between the different TDD configurations of aggregated carriers. This intermediary mechanism allows the system to handle multiple TDD configurations simultaneously by establishing separate HARQ timing rules for each carrier, thereby preventing ACK/NACK scheduling conflicts while maintaining the flexibility of different UL-DL ratios

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP2774308B1Selection of acknowledgment timing in wireless communications

Publication Date: 2021.07.07 APPLE INC

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AI summary

Disclosed is a method including communicating, by a mobile device, with a base station via first and second component carriers having different frequency bands and time division duplexing (TDD) configurations. The method may include receiving one or more downlink transmissions via the second component carrier. The method may include selecting a hybrid automatic repeat request (HARQ) timing sequence based on the TDD configurations of the first and second component carriers. The method may include transmitting one or more positive acknowledgment and/or negative acknowledgement (ACK/NACK) signals, associated with the one or more downlink transmissions, according to the selected HARQ timing sequence. Other embodiments may be described and claimed.