HARQ ACK/NACK Bundling Scrambling in Dynamic TDD Systems

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Solution Overview

Problem

In dynamic TDD systems, determining the value of Nbundled for HARQ bit scrambling on PUSCH is challenging due to the unavailability of Downlink Assignment Index (DAI) in DCI format 0/4, leading to ambiguity in UL/DL configuration and inefficient resource allocation.

Innovation Solution

A method and apparatus for choosing or calculating a scramble code selecting parameter from a predefined set, associated with downlink subframes or based on detected downlink assignments, to scramble and descramble HARQ ACK/NACK bits on PUSCH, ensuring proper bundling and minimizing complex calculations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If DAI is not included in DCI format 0/4 for dynamic TDD, then UL/DL configuration flexibility is improved, but HARQ bit scrambling accuracy deteriorates

Engineering Contradiction:

ImproveUL/DL configuration flexibilityVSAvoidHARQ bit scrambling accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent introduces a reference TDD configuration as an intermediary element that mediates between the need for dynamic UL/DL configuration and the requirement for accurate HARQ bit scrambling. The reference configuration provides a stable baseline that both the eNB and UE can use to determine Nbundled values, even when the actual dynamic configuration changes. This intermediary reference allows the system to maintain scrambling accuracy without being constrained by fixed DAI inclusion in DCI formats.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the parameter determination approach from relying on DAI in DCI format 0/4 to using a combination of reference TDD configuration and detected downlink subframes. By changing how Nbundled is calculated - using the reference configuration as a baseline and adjusting based on actual detected subframes - the system achieves both dynamic adaptability and scrambling accuracy without the harmful constraint of including DAI in DCI formats.

Inventive Principle:

Principle #35Parameter changes

2Productivity

If dynamic TDD configuration is used, then resource allocation efficiency is improved, but determination of Nbundled value becomes ambiguous

Engineering Contradiction:

Improveresource allocation efficiencyVSAvoidNbundled value ambiguity

Core Design Contradiction:

ProductivityVSLoss of information

Solution Approach 1:

The patent applies preliminary action by establishing a reference TDD configuration before dynamic adjustments are made. This reference configuration is set in advance and provides a known baseline for determining Nbundled values. When dynamic configuration changes occur, the UE and eNB can both refer back to this pre-established reference to resolve any ambiguity about the correct Nbundled value, thus maintaining information integrity while enabling dynamic resource allocation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where the UE detects downlink subframes and uses this detection feedback, combined with the reference TDD configuration, to determine the Nbundled value. The feedback loop ensures that both the eNB and UE arrive at the same Nbundled value by independently calculating it based on the same reference configuration and detected subframes, eliminating ambiguity while preserving dynamic TDD benefits.

Inventive Principle:

Principle #23Feedback

3Stability of the object's composition

If fixed TDD configuration is used, then HARQ scrambling consistency is improved, but resource utilization flexibility deteriorates

Engineering Contradiction:

ImproveHARQ scrambling consistencyVSAvoidresource utilization flexibility

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent applies dynamics by introducing a reference TDD configuration that remains stable while allowing dynamic adjustments around it. The reference configuration provides the consistent foundation needed for HARQ scrambling consistency, while the ability to dynamically detect and adapt to actual downlink subframes enables flexible resource utilization. This dynamic approach allows the system to maintain consistency where needed (through the reference) while adapting where flexibility is required (through dynamic detection).

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS9860026B2Methods, user equipment and radio network node for HARQ ACK/NACK bundling on PUSCH in a dynamic TDD system

Publication Date: 2018.01.02 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

The present disclosure relates to a method for HARQ ACK/NACK bundling on a PUSCH in a TDD system. The method comprises choosing a scramble code selecting parameter from a predefined set of scramble code selecting parameters, wherein each scramble code selecting parameter is associated with one of one or more downlink subframes to be received and one or more HARQ ACK/NACK bits with respect to the one or more downlink subframes are to be transmitted in a predetermined uplink subframe, or calculating a scramble code selecting parameter based on the number of detected downlink subframes. The method also comprises scrambling one or more HARQ ACK/NACK bits using the chosen scramble code selecting parameter or the calculated scramble code selecting parameter for bundling on the PUSCH. The present disclosure also relates to corresponding UE and a radio network node for HARQ ACK/NACK bundling on a PUSCH in a TDD system.