Recurrent Equivariant Inference for MIMO Channel Estimation

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Solution Overview

Problem

Current wireless communication systems face challenges in accurate channel estimation due to high overhead and interference in multiple-input and multiple-output (MIMO) communications, leading to inconsistent and inaccurate channel resource estimation.

Innovation Solution

The implementation of recurrent equivariant inference machines for channel estimation, which utilize pilot symbols like demodulation reference signals (DMRS) to generate multiple channel estimations per layer and refine them through iterative processes involving gradients and latent variables, reducing the need for tracking reference signals and accounting for cross-MIMO interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional channel estimation methods are used in MIMO communications, then channel estimation can be performed, but high overhead and interference lead to inconsistent and inaccurate channel resource estimation

Engineering Contradiction:
Improvechannel estimation accuracyVSAvoidcomputational overhead
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical signal processing methods with a neural network-based inference machine. The recurrent equivariant inference machine uses learned patterns from pilot symbols to directly predict channel characteristics, substituting complex iterative mathematical computations with a trained neural network model that achieves higher accuracy with reduced computational overhead.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent transforms the channel estimation problem by changing the parameter representation through latent variables. The neural network learns optimal parameter transformations that capture essential channel characteristics in a compressed latent space, enabling accurate estimation while reducing the dimensionality and complexity of the estimation process.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If multiple channel estimations per layer are generated and refined through iterative processes, then channel estimation accuracy is enhanced, but computational complexity increases

Engineering Contradiction:
Improvechannel estimation accuracyVSAvoidcomputational power
Core Design Contradiction:
Measurement precisionVSPower

Solution Approach 1:

The patent performs preliminary channel estimation using pilot symbols before actual data transmission. The recurrent equivariant inference machine pre-learns channel characteristics and patterns during training, so that during operation, it can rapidly generate accurate estimations without requiring extensive iterative computations at runtime, thus reducing real-time computational power requirements.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses pilot symbols as copies of known channel characteristics to infer unknown channel states. By comparing the known pilot symbol transmissions with their received versions, the system creates reference copies that the neural network uses to predict and refine channel estimations for data symbols, reducing the need for complex iterative processing.

Inventive Principle:
Principle #26Copying

3Measurement precision

If tracking reference signals are used to improve channel estimation, then estimation accuracy improves, but overhead increases

Engineering Contradiction:
Improvechannel estimation accuracyVSAvoidsignal overhead
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent makes the pilot symbols multi-functional by designing them to serve both as channel estimation references and as training data for the recurrent equivariant inference machine. The same pilot symbols are used for initial channel estimation and for the neural network to learn temporal and spatial channel patterns, eliminating the need for separate tracking reference signals and reducing overall overhead.

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

Solution Approach 2:

The system enables the pilot symbols to self-serve multiple purposes. The pilot symbols automatically provide both the initial channel state information and the training data needed for the neural network to learn and adapt to channel characteristics, making the system self-sufficient without requiring additional dedicated tracking reference signals.

Inventive Principle:
Principle #25Self-service

Data Source

PatentUS20240113917A1Recurrent equivariant inference machines for channel estimation
Publication Date: 2024.04.04 QUALCOMM INC
  • US20240113917A1 patent drawing
  • US20240113917A1 patent drawing
  • US20240113917A1 patent drawing

AI summary

Methods, systems, and devices for wireless communications are described. A wireless device may receive an assignment of a set of resources associated with a channel where the set of resources includes a first subset of resources allocated for data transmission and a second subset of resources allocated for a reference signal. The wireless device may generate multiple channel estimations per layer of the channel and perform a refinement operation utilizing the estimations to generate a channel estimation associated with multiple layers. Each iteration of the refinement operation may include generating respective gradients associated with each per layer channel estimation; generating a current set of values of a latent variable; and modifying the channel estimations.