Aggressive NACK Timing Configuration for Wireless Packet Recovery

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Solution Overview

Problem

In wireless communication systems, particularly in LTE, there is a delay in sending negative acknowledgments (NACKs) after a user equipment (UE) tunes away from an active network and returns, leading to a significant delay in recovering missed packets due to the reliance on a default reordering timer.

Innovation Solution

The UE modifies its NACK timing configuration to an aggressive configuration for a configurable period, allowing for faster transmission of NACKs upon detecting missed packets after tuning back, thereby reducing the delay in recovering missed data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE uses the default reordering timer configuration, then the system maintains stability and proper packet reordering, but the recovery of missed packets experiences significant delay

Engineering Contradiction:
Improvepacket reordering reliabilityVSAvoidmissed packet recovery delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the NACK timing configuration adjustable rather than fixed. The system transitions from a static default configuration to a dynamic configuration that can switch between default and aggressive modes based on whether packets are received out of order, allowing the NACK timing behavior to adapt to actual network conditions

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the timing parameter of NACK transmission by introducing an aggressive NACK timing configuration with shorter delays compared to the default configuration. This parameter change allows the system to send NACKs more quickly when needed, reducing the recovery delay for missed packets while maintaining the option to use the original default timing when appropriate

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the UE sends NACKs immediately upon detecting missed packets, then the recovery speed improves, but the risk of premature NACK transmission increases

Engineering Contradiction:
Improvepacket recovery speedVSAvoidNACK transmission accuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent applies preliminary action by pre-configuring multiple NACK timing configurations (default and aggressive) before they are needed. The system prepares the aggressive configuration in advance, so when out-of-order packets are detected, it can immediately switch to using the pre-prepared aggressive timing without any additional processing delay

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses feedback by monitoring packet reception order and using this information to dynamically select the appropriate NACK timing configuration. When packets are received out of order, the system feedback-indicates that the aggressive configuration should be used; otherwise, the default configuration remains in effect, ensuring NACKs are only accelerated when actually needed

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3130098B1Methods and apparatus for sending fast negative acknowledgements (NACKS)
Publication Date: 2020.02.19 QUALCOMM INC
  • EP3130098B1 patent drawingFigure 1
  • EP3130098B1 patent drawingFigure 2
  • EP3130098B1 patent drawingFigure 3

AI summary

Certain aspects of the present disclosure relate to methods and apparatus for sending fast negative acknowledgements (NACKs) after a user equipment (UE) tunes back to a first network after tuning away from the first network. The UE may determine that a trigger event has occurred, and in response to the determination, modify a NACK timing configuration from a default configuration. Modifying the NACK timing configuration may include using an aggressive NACK timing configuration for a configurable period of time, in response to detecting a trigger event. The trigger event may include detecting missed packets after a tune back, unavailability of sufficient memory to hold packets until a gap created by missed packets may be filled, or tuning back to a network.