Uplink Link Adaptation Using Q-Learning for MCS Prediction

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Solution Overview

Problem

Current 5G NR systems rely on static look-up tables for link adaptation, which fail to account for individual cell environment and UE parameters, leading to inefficient resource consumption and robustness, and are dependent on estimated SINR values.

Innovation Solution

A method using Q-learning to predict a second MCS value based on a first MCS value, transmission type, and feedback acknowledgement, adjusting the MCS to optimize uplink transmissions and reduce Block Error Rate (BLER).

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If static look-up tables are used for link adaptation, then the system is simple to implement, but it fails to adapt to individual cell environment and UE parameters, leading to poor transmission performance

Engineering Contradiction:
ImproveImplementation simplicityVSAvoidTransmission performance
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent transforms the static link adaptation system into a dynamic one by implementing a machine learning model that continuously learns from transmission outcomes (ACK/NACK feedback) and adapts MCS selections to specific cell environments and UE characteristics. The system evolves its decision-making process over time, moving from fixed look-up tables to adaptive predictions based on learned patterns.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the fundamental parameter selection approach from static table-based indexing to dynamic machine learning predictions. The system learns optimal MCS values by analyzing relationships between channel conditions, UE parameters, and transmission outcomes, allowing flexible adaptation to varying conditions rather than relying on pre-defined static mappings.

Inventive Principle:
Principle #35Parameter changes

2Use of energy by moving object

If static look-up tables are used for link adaptation, then the system requires minimal computational resources, but it is highly dependent on estimated SINR values and ignores important environmental information

Engineering Contradiction:
ImproveComputational resource consumptionVSAvoidCell environment and UE parameter information
Core Design Contradiction:
Use of energy by moving objectVSLoss of information

Solution Approach 1:

The patent introduces a machine learning model as an intermediary between raw input features (SINR, UE parameters, transmission type) and MCS selection. This intermediary processes and integrates multiple information sources, learning complex relationships and patterns that static tables cannot capture, thereby reducing information loss while maintaining reasonable computational requirements.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The machine learning model serves multiple functions simultaneously: it processes SINR estimates, incorporates UE-specific parameters, accounts for transmission type (new vs. retransmission), and learns cell-specific patterns. This multi-functional approach consolidates what would otherwise require separate processing systems, achieving comprehensive information utilization with efficient resource consumption.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Stability of the object's composition

If traditional link adaptation methods are used, then the system maintains fixed BLER targets, but it cannot adapt to changing channel conditions and transmission outcomes

Engineering Contradiction:
ImproveFixed BLER targetVSAvoidAdaptation to changing conditions
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent implements a feedback mechanism where the machine learning model receives ACK/NACK outcomes from previous transmissions and uses this information to refine future MCS selections. The system learns from past performance, adjusting its predictions based on whether transmissions succeeded or failed, thereby adapting to changing channel conditions while maintaining stable operational goals.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The machine learning model performs preliminary learning during system operation, accumulating knowledge about cell-specific characteristics and UE behavior patterns. This preliminary action of learning and adaptation occurs continuously in the background, enabling the system to proactively adjust to changing conditions rather than reactively responding to performance degradation.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS20250385747A1Method and network node for link adaptation
Publication Date: 2025.12.18 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • US20250385747A1 patent drawing
  • US20250385747A1 patent drawing
  • US20250385747A1 patent drawing

AI summary

The invention relates to a method for performing a link adaptation in an uplink transmission between a user equipment, UE, and a network node in a telecommunication network, the method comprising:obtaining a first value of a Modulation and Coding Scheme, MCS, for a future transmission at transmission time interval k in the uplink transmission, the first value of MCS being determined on the basis of a Signal to Interference and Noise Ratio, SINR, estimated by the network node for the future transmission at transmission time interval k; andpredicting a second value of the MCS for the future transmission at transmission time k by using a Q-learning process having as input the first value of MCS, first data indicating whether the future transmission at transmission time k is a first transmission or a retransmission, and second data indicating whether a feedback acknowledgement, ACK/NACK, of a transmission that took place at transmission time interval k−1 is equal to ACK or NACK.