Non-linear Precoding MU-MIMO Interference Reduction

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Solution Overview

Problem

Existing MIMO technologies in wireless networks, such as WLANs, face inadequate performance in terms of data throughput and link range, particularly due to limitations in multi-user multiple-input multiple-output (MU-MIMO) systems which struggle with interference and user ordering issues.

Innovation Solution

The implementation of non-linear coding based MU-MIMO systems, where a station or access point processes null packets to generate channel feedback, determines QR-dependent information, and sends data streams, utilizing modulo operations and QR decomposition to optimize user ordering and reduce interference, thereby enhancing bit-error rate performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If linear precoding is used in MU-MIMO systems, then implementation complexity is reduced, but interference between users increases and performance deteriorates

Engineering Contradiction:

Improveimplementation complexityVSAvoidMU-MIMO performance

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent changes the mathematical approach from linear precoding to non-linear precoding using QR decomposition. This parameter change in the signal processing method enables effective interference cancellation while maintaining practical implementation complexity through structured algorithms.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces QR decomposition as an intermediary mathematical tool that facilitates non-linear precoding. The QR factorization serves as a mediator between the channel state information and the precoded signals, enabling interference management without requiring direct complex non-linear operations.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If user ordering is not optimized, then system implementation is simpler, but bit-error rate performance deteriorates due to interference

Engineering Contradiction:

Improvesystem implementation simplicityVSAvoidbit-error rate performance

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent applies preliminary user ordering based on channel conditions before performing non-linear precoding. By pre-ordering users according to their channel characteristics, the system optimizes interference cancellation effectiveness and bit-error rate performance before the actual signal processing occurs.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements dynamic user ordering that adapts to changing channel conditions. The ordering strategy is not fixed but adjusts based on real-time channel state information, allowing the system to maintain optimal performance as channel conditions vary over time.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentEP2974067B1Station and access point for non-linear precoding based multiuser multiple input multiple output

Publication Date: 2019.11.06 INTERDIGITAL PATENT HOLDINGS INC

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AI summary

A station is used to implement non-linear coding based multiuser multiple-input multiple-output (MU-MIMO). The station includes a processor that may be configured to perform a number of actions. For example, the processor receives a null packet from an access point (AP). Channel feedback is generated using the null packet. The channel feedback is sent to the AP. QR dependent information is received from the AP. Data is sent to the AP according to the QR dependent information.