Listen Again After Talk Collision Detection in Wireless Broadcast

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Solution Overview

Problem

Current wireless communication systems face challenges in detecting collisions during multi-cast and broadcast transmissions using Listen-Before-Talk (LBT) procedures, particularly in unlicensed access mediums, leading to potential collisions and inefficient medium utilization.

Innovation Solution

Implementing a Listen Again After Talk (LAAT) procedure, where wireless devices adjust their transmission schedules and LBT parameters based on detected collisions, using modified transmission frames with randomized timing and configuration to detect collisions and optimize access medium usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If Listen-Before-Talk (LBT) procedure is used to determine whether accessing the carrier is allowed, then medium access control is improved, but collision detection capability deteriorates

Engineering Contradiction:
Improvemedium access controlVSAvoidcollision detection capability
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The patent introduces a preliminary listening period within the transmission frame structure, where the wireless device listens for collisions before actually transmitting data. This preliminary action (listening) is taken in advance of the main transmission activity, allowing the device to detect potential collisions early and adjust its transmission schedule accordingly, thus resolving the contradiction between maintaining LBT-based medium access control and improving collision detection capability

Inventive Principle:
Principle #10Preliminary action

2Device complexity

If transmission frames are scheduled at fixed intervals, then transmission scheduling simplicity is improved, but collision probability increases

Engineering Contradiction:
Improvetransmission scheduling simplicityVSAvoidcollision probability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent makes the transmission frame timing dynamic by introducing randomization within a defined window. Instead of fixed periodic scheduling, the transmission frames are scheduled at randomized times within a configurable window, which maintains reasonable scheduling simplicity while significantly reducing collision probability through temporal dispersion of transmissions

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the timing parameter from a fixed value to a randomized value within a window. This parameter change allows the system to maintain the simplicity of scheduled transmission while introducing variability that reduces collision probability, directly resolving the contradiction between scheduling simplicity and collision avoidance

Inventive Principle:
Principle #35Parameter changes

3Measurement precision

If Listen Again After Talk (LAAT) procedure is implemented with randomized timing, then collision detection accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvecollision detection accuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the transmission frame into distinct functional parts: a listening period for collision detection and a data transmission period. This segmentation allows the device to perform collision detection with improved accuracy during the listening period while keeping the overall device complexity manageable by clearly defining the boundaries and purposes of each segment

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3629666B1Listen again after talk for broadcast/multi-cast communications
Publication Date: 2024.01.17 APPLE INC
  • EP3629666B1 patent drawingFigure 1A~1B
  • EP3629666B1 patent drawingFigure 2
  • EP3629666B1 patent drawingFigure 3

AI summary

Apparatuses, systems, and methods for a wireless device to perform methods to implement mechanisms for performing a listen again after talk procedure to detect collisions over an access medium. The wireless device may determine a frequency and configuration of modified transmission frames for transmission over an access medium (licensed or unlicensed) and may further determine a timing of the modified transmission frames within a transmission occasion. The wireless device may detect, during a listening period of the modified transmission frame, a collision and may adjust, based, at least in part, on the detected collision, a remaining transmission schedule for the transmission schedule and/or LBT parameters.