Mobile Station HARQ Buffer Flush for PUSCH Retransmission Control

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Solution Overview

Problem

In wireless communication systems, mobile station apparatuses experience repeated retransmissions of PUSCH due to decoding results not being properly handled when a downlink component carrier is excluded from downlink communication, leading to inefficient control of retransmissions.

Innovation Solution

Implementing a method where the mobile station apparatus flushes HARQ buffers associated with downlink component carriers not used for downlink communication, and sets ACK without receiving HARQ indicators, allowing for efficient control of PUSCH retransmissions by deactivating unused downlink component carriers based on commands or elapsed time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the mobile station apparatus continues to monitor PHICH for HARQ indicators on deactivated downlink component carriers, then it can receive decoding results, but it causes unnecessary retransmissions and reduces communication efficiency

Engineering Contradiction:

ImproveHARQ feedback receptionVSAvoidcommunication efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent extracts the monitoring function for deactivated downlink component carriers and removes it from the mobile station apparatus operation. When a downlink component carrier is deactivated, the mobile station stops monitoring the PHICH on that carrier, thereby eliminating unnecessary retransmissions while maintaining reliable HARQ feedback reception on active carriers.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent implements dynamic adjustment of PHICH monitoring behavior based on the activation state of downlink component carriers. The mobile station apparatus dynamically switches between monitoring and non-monitoring states for PHICH depending on whether the associated downlink component carrier is activated or deactivated, optimizing communication efficiency while maintaining reliability.

Inventive Principle:

Principle #15Dynamics

2Reliability

If the mobile station apparatus monitors all configured downlink component carriers for PHICH signals, then it ensures complete HARQ feedback reception, but it increases processing overhead and prevents efficient resource utilization

Engineering Contradiction:

ImproveHARQ feedback completenessVSAvoidprocessing overhead

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent extracts deactivated downlink component carriers from the set of carriers requiring PHICH monitoring. The mobile station apparatus only monitors PHICH on actively used downlink component carriers, removing the processing overhead associated with monitoring deactivated carriers while ensuring complete HARQ feedback reception for active carriers.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies partial monitoring action by having the mobile station apparatus monitor PHICH only on a subset of downlink component carriers that are currently activated. Instead of monitoring all configured carriers, it performs partial monitoring limited to active carriers, reducing processing overhead while maintaining necessary HARQ feedback completeness.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If the mobile station apparatus performs retransmission based on NACK feedback from deactivated carriers, then it maintains HARQ protocol compliance, but it causes unnecessary retransmissions and wastes uplink resources

Engineering Contradiction:

ImproveHARQ protocol complianceVSAvoiduplink resource utilization

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent extracts deactivated downlink component carriers from the set of carriers that trigger retransmission operations. When the mobile station apparatus determines that a downlink component carrier is deactivated, it excludes PHICH from that carrier from triggering retransmission, thereby maintaining HARQ protocol compliance for active carriers while eliminating unnecessary retransmissions to deactivated carriers.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies preliminary anti-action by having the mobile station apparatus proactively identify deactivated downlink component carriers and prevent retransmission operations before they occur. By detecting the deactivated state in advance, the system avoids initiating unnecessary retransmissions that would waste uplink resources, while still complying with HARQ protocols for active carriers.

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS9686047B2Wireless communication method, mobile station apparatus, wireless communication system and integrated circuit

Publication Date: 2017.06.20 SHARP KK

AI summary

To perform control of PUSCH retransmission efficiently in a wireless communication system where a mobile station apparatus and a base station apparatus communicate with each other using a plurality of downlink component carriers. In a mobile station apparatus which communicates with a base station apparatus using a plurality of downlink component carriers and a plurality of uplink component carriers, in case that the downlink component carrier corresponding to the uplink component carrier is set not to be used for downlink communication, the mobile station apparatus flushes HARQ buffers of the uplink component carrier associated with the downlink component carrier set not to be used for downlink communication.