Multi-Beam LBT for Millimeter Wave MU-MIMO Interference

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Solution Overview

Problem

In millimeter wave multi-user multiple-input multiple-output (MU-MIMO) communications, the challenge lies in managing interference between independent communication streams, which can lead to self-interference, and existing listen before talk (LBT) procedures may not effectively handle simultaneous transmissions across multiple beams.

Innovation Solution

A method where a wireless device performs multiple LBT procedures based on different timers for various beams, allowing simultaneous MU-MIMO transmissions by ensuring that each beam is clear before data is sent, thereby avoiding interference and optimizing beam usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single LBT procedure is used for all beams, then the procedure is simple to implement, but it cannot handle simultaneous transmissions across multiple beams effectively

Engineering Contradiction:
ImproveLBT procedure complexityVSAvoidsimultaneous transmission capability
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The patent divides the single LBT procedure into multiple separate LBT procedures, with each procedure associated with a specific beam. This segmentation allows independent channel assessment for each beam, enabling simultaneous transmissions across multiple beams while maintaining manageable complexity through modular design

Inventive Principle:
Principle #1Segmentation

2Productivity

If multiple LBT procedures are performed for different beams, then simultaneous MU-MIMO transmissions are enabled, but the device complexity increases

Engineering Contradiction:
Improvesimultaneous transmission capacityVSAvoidnumber of LBT procedures
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent implements preliminary actions by performing LBT procedures before actual data transmissions. Each beam performs its LBT assessment in advance, allowing the system to prepare multiple simultaneous transmissions without interference. This preliminary channel assessment enables the complex multi-beam operation to be managed systematically

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent introduces dynamic management of multiple LBT procedures with timers that can be started, stopped, or restarted based on transmission needs. The system dynamically adjusts which beams are active and when LBT procedures should be performed, optimizing the balance between simultaneous transmission capability and system complexity

Inventive Principle:
Principle #15Dynamics

3Reliability

If beams are cleared individually before transmission, then interference is avoided, but transmission time is increased

Engineering Contradiction:
Improveinterference avoidanceVSAvoidLBT procedure duration
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent performs LBT procedures as preliminary actions before data transmissions. By completing channel assessments in advance for all intended beams, the system ensures interference-free transmissions while minimizing the time overhead, as the LBT procedures are completed before the actual data transmission window begins

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3704804B1Listen before talk for millimeter wave multi-user multiple-input multiple-output communications
Publication Date: 2023.09.27 QUALCOMM INC
  • EP3704804B1 patent drawingFigure 1
  • EP3704804B1 patent drawingFigure 2
  • EP3704804B1 patent drawingFigure 3

AI summary

Methods, systems, and devices for wireless communications are described. A wireless device may include a plurality of antenna panels. The wireless device may perform a first listen before talk (LBT) procedure for a configuration of a first antenna panel based at least in part on a first LBT timer and may perform a second LBT procedure for a configuration of a second antenna panel based at least in part on a second LBT timer. The wireless device may then perform a multiple user multiple-input multiple-output (MU-MIMO) transmission. The MU-MIMO transmission may include transmitting a first packet to a second wireless device using the configuration of the first antenna and transmitting a second packet to a third wireless device using the configuration of the second antenna.