UE HARQ Decoding Power Reduction via Periodic Wake-Up

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Solution Overview

Problem

In wireless communication networks, user equipment (UE) continues to decode acknowledgement channels even after receiving a positive acknowledgement, leading to increased power consumption as it cannot stay in a low power state, potentially resulting in packet loss if a negative acknowledgement is misinterpreted.

Innovation Solution

The UE is allowed to stay in a low power state for a specified time after receiving an acknowledgement, ignoring subsequent acknowledgement channels, and then wake up to decode them in time for retransmissions, thereby reducing power consumption while minimizing packet loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE continues to decode acknowledgement channels after receiving a positive acknowledgement, then the reliability of packet transmission is improved, but the power consumption increases and the UE cannot stay in a low power state

Engineering Contradiction:
Improvepacket transmission reliabilityVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The UE periodically wakes up from low power state to decode acknowledgement channels at specific intervals (e.g., every 4 subframes) rather than continuously decoding. This periodic action allows the UE to maintain reliability by detecting retransmission grants while consuming less power by staying in low power state between decoding intervals.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The UE performs preliminary decoding of acknowledgement channels only when necessary (upon waking from low power state) rather than continuously. By anticipating when decoding is needed and preparing in advance, the UE can enter low power state sooner and wake up only when a retransmission grant is expected, reducing overall power consumption while maintaining transmission reliability.

Inventive Principle:
Principle #10Preliminary action

2Use of energy by moving object

If the UE enters a low power state immediately after receiving an acknowledgement, then the power consumption is reduced, but the risk of packet loss increases if a negative acknowledgement is misinterpreted

Engineering Contradiction:
Improvepower consumptionVSAvoidpacket transmission reliability
Core Design Contradiction:
Use of energy by moving objectVSReliability

Solution Approach 1:

The UE uses feedback from periodically decoding acknowledgement channels to verify whether the initial positive acknowledgement was correct. By waking up at intervals to check for retransmission grants or negative acknowledgements, the UE can detect misinterpreted ACKs and correct errors, maintaining reliability while spending most time in low power state to reduce consumption.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The UE dynamically adjusts its decoding behavior based on the received acknowledgement state. After receiving an ACK, the UE transitions to low power state but maintains the capability to wake up and decode if needed. This dynamic state transition allows the UE to optimize between power savings and reliability based on actual network conditions and HARQ process status.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP2756716B1Methods and apparatus to reduce power consumption for HARQ decoding
Publication Date: 2018.07.04 QUALCOMM INC
  • EP2756716B1 patent drawingFigure 1
  • EP2756716B1 patent drawingFigure 2
  • EP2756716B1 patent drawingFigure 3

AI summary

Certain aspects of the present disclosure may help reduce power consumption by allowing a UE to remain in a low power state by not attempting to decode ACK/NACK transmissions after receiving a positive acknowledgement (ACK).