LTE User Terminal LBT Sensing Subframe Configuration

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Solution Overview

Problem

In LTE systems operating in unlicensed bands, there is a risk of significant cross-interference due to the lack of coordination between different operators and systems, as existing technologies do not have suitable frame configurations for Listen Before Talk (LBT) functions in uplink signals, making it difficult to prevent interference.

Innovation Solution

A user terminal equipped with a receiving process for detecting channel states in unlicensed bands using LBT in designated sensing subframes, with a control section managing these subframes based on specific sensing patterns to avoid interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If LTE systems operate in unlicensed bands without coordinated frame configuration for LBT, then frequency band utilization is improved, but cross-interference between different operators and systems increases significantly

Engineering Contradiction:

Improvefrequency band utilizationVSAvoidcross-interference

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by configuring specific subframes as sensing subframes before actual uplink transmission. User terminals perform LBT sensing in advance in these designated subframes to detect channel availability, ensuring interference-free transmission opportunities are identified and utilized before other systems attempt transmission.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent segments the unlicensed band spectrum into specific sensing subframes within the LTE frame structure. By designating certain subframes (e.g., uplink subframes or special subframes) as sensing subframes, the system creates structured opportunities for LBT operations, separating sensing functions from regular data transmission functions.

Inventive Principle:

Principle #1Segmentation

2Reliability

If LBT sensing is performed in all subframes, then interference prevention is improved, but system complexity and overhead increase

Engineering Contradiction:

Improveinterference preventionVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies local quality by applying LBT sensing operations selectively only in specific sensing subframes rather than uniformly across all subframes. This localized approach concentrates sensing resources where they are most needed for interference prevention while leaving other subframes for regular communication operations.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements partial action by performing LBT sensing in only a subset of subframes (the designated sensing subframes) rather than in every subframe. This partial sensing approach provides sufficient interference prevention capability while reducing the overall sensing overhead and system complexity compared to continuous sensing.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS11218883B2User terminal, radio base station, radio communication method and radio communication system

Publication Date: 2022.01.04 NTT DOCOMO INC

AI summary

A user terminal is disclosed that includes a processor that determines a predetermined period based on information about a configuration of sensing. The user terminal further includes a receiver that performs a sensing before transmitting signals in the predetermined period. A radio communication method for a user terminal is also disclosed that includes determining a predetermined period based on information about the configuration of sensing and performing a sensing before transmitting signals in the predetermined period.