Non-linear Modulation for HARQ Feedback in 5G Uplink

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Solution Overview

Problem

In wireless communication systems, particularly in 5G NR, the increasing frequency range and decreasing latency lead to increased overhead, necessitating more efficient mechanisms for communicating overhead information, such as using non-linear modulation to convey HARQ feedback without additional overhead resources.

Innovation Solution

The implementation of non-linear functions or models to modulate data, allowing user equipment (UE) to transmit HARQ feedback by applying different non-linear power amplifier models, which can be estimated by network nodes to determine the feedback, thereby eliminating the need for separate control channels and increasing available HARQ ACK/NACK bits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If non-linear modulation is used to convey HARQ feedback, then overhead efficiency is improved, but signal processing complexity increases

Engineering Contradiction:

Improveoverhead information efficiencyVSAvoidsignal processing complexity

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

The patent changes the modulation parameter from linear to non-linear by applying non-linear functions (such as power amplifier models with different saturation characteristics) to the reference signal. This allows HARQ feedback information to be embedded in the amplitude/power domain rather than requiring separate control channels, thereby improving overhead efficiency while the receiver estimates the non-linear function parameters to decode the feedback.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If separate control channels are used for HARQ feedback, then reliability is improved, but overhead resources increase

Engineering Contradiction:

ImproveHARQ feedback reliabilityVSAvoidoverhead resources

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent merges the HARQ feedback information with the uplink data transmission by modulating the reference signal embedded in the data stream. Instead of using separate control channels (PUCCH), the feedback is conveyed through non-linear modulation of the PUSCH reference signal, combining both data and control information in the same physical channel to reduce overhead resources.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The reference signal serves multiple functions: it enables channel estimation for data reception and simultaneously conveys HARQ feedback information through non-linear modulation. This multi-functionality eliminates the need for dedicated control channels, reducing overhead while maintaining reliable feedback transmission.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11770217B2Techniques for using a non-linear model to indicate data in wireless communications

Publication Date: 2023.09.26 QUALCOMM INC

AI summary

Aspects described herein relate to converting, by applying a non-linear function, a symbol indicating first data into an analog signal for transmitting to a network node, wherein applying the non-linear function indicates second data, separate from first data, and transmitting the analog signal to the network node. Additional aspects relate to receiving an analog signal from a user equipment (UE), and estimating a non-linear function applied to the analog signal in converting a symbol indicating first data into the analog signal, wherein estimating the non-linear function indicates second data, separate from first data.