eMMB and URLLC Link Adaptation with Selective HARQ Retransmission

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Solution Overview

Problem

Existing data transmission systems in telecom networks face challenges in maintaining high reliability while avoiding packet delays beyond the allowed packet delay budget (PDB) and increasing failure rates due to conservative link adaptation methods and HARQ retransmissions.

Innovation Solution

Implement a modified outer loop link adaptation (OLLA) method that selectively adjusts the SINR for a single HARQ process based on recent ACK feedback, allowing proactive retransmissions and optimizing data transmission rates without increasing latency or failure rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conservative link adaptation methods are used to ensure high reliability, then reliability is improved, but data transmission efficiency deteriorates and unnecessary retransmissions increase

Engineering Contradiction:

ImprovereliabilityVSAvoiddata transmission efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies different link adaptation strategies to different HARQ processes based on their individual performance characteristics. Instead of using a single conservative approach for all processes, the system identifies and treats successful HARQ processes differently from unsuccessful ones, allowing aggressive adaptation for reliable processes while maintaining caution for unreliable ones, thus resolving the contradiction between reliability and transmission efficiency

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements dynamic link adaptation by continuously monitoring HARQ feedback and adjusting the modulation and coding scheme (MCS) in real-time. The system dynamically switches between conservative and aggressive adaptation strategies based on recent HARQ outcomes, enabling the system to optimize between reliability and efficiency according to current channel conditions and recent performance trends

Inventive Principle:

Principle #15Dynamics

2Reliability

If HARQ retransmissions are used to improve reliability, then reliability is improved, but packet delay increases and latency requirements are not met

Engineering Contradiction:

ImprovereliabilityVSAvoidpacket delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary actions by proactively adjusting the MCS before transmission based on predicted channel conditions and recent HARQ feedback patterns. By anticipating potential failures and pre-adjusting parameters, the system reduces the need for reactive retransmissions and minimizes delay, resolving the contradiction between reliability improvement through retransmission and latency requirements

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent enables skipping unnecessary retransmission steps by identifying HARQ processes that are likely to succeed based on channel conditions and recent performance, allowing the system to rush through successful transmissions without waiting for potential retransmissions. This selective skipping of retransmission steps reduces overall packet delay while maintaining reliability

Inventive Principle:

Principle #21Skipping (Rushing through)

3Productivity

If aggressive link adaptation is used to increase transmission rate, then productivity is improved, but failure rate increases and reliability deteriorates

Engineering Contradiction:

Improvetransmission rateVSAvoidfailure rate

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies partial aggressive action by selectively using aggressive link adaptation only for HARQ processes that demonstrate recent success and reliable channel conditions. Instead of applying aggressive adaptation universally (which would increase failure rate), the system applies it partially to suitable processes while maintaining conservative adaptation for unreliable processes, thus resolving the contradiction between transmission rate and failure rate

Inventive Principle:

Principle #16Partial or excessive action

4Measurement precision

If multiple HARQ processes are monitored for link adaptation, then adaptation accuracy is improved, but system complexity increases

Engineering Contradiction:

Improveadaptation accuracyVSAvoidsystem complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the monitoring task by focusing adaptation accuracy on a subset of HARQ processes rather than all processes uniformly. By segmenting the monitoring scope to prioritize recently successful processes, the system achieves high adaptation accuracy for critical transmissions without the overwhelming complexity of monitoring every single HARQ process in detail

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS20250300771A1PERFORMANCE OPTIMIZATIONS FOR eMMB and URLLC APPLICATIONS WITH HIGH RELIABILITY REQUIREMENTS

Publication Date: 2025.09.25 MAVENIR US INC

AI summary

A system and method for optimizing data transmission rates in telecom systems requiring very high reliability that accounts for retransmissions of data and corresponding HARQ feedback and using HARQ retransmission to: avoid packets being delayed beyond their allowed PDB for associated radio bearers, avoid increasing failure rate, and avoids increasing latency due to the stop and wait protocol employed for HARQ retransmission, by transmitting NACK via RLC protocol avoiding multiple retransmissions on receiving a HARQ NACK for a selected HARQ process.