Epoch-Based Interference Detection for LTE in Unlicensed Spectrum

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Solution Overview

Problem

LTE systems face challenges in efficiently operating in unlicensed spectrum due to lack of interference awareness, leading to channel collisions and spectrum underutilization, as they lack visibility into channel state and rely on eNB-driven channel access procedures that are not scalable or accurate in estimating interference from hidden terminals.

Innovation Solution

The Epoch-based Interference (ELI) method equips eNBs to accurately detect and measure interference, collects interference statistics in a scalable manner, and leverages this information through novel access techniques to improve channel access performance, using orthogonal frequency-division multiple access (OFDMA) to reduce measurement overhead and cluster clients with similar interference profiles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If LTE uses traditional eNB-driven channel access procedures, then channel access is simplified, but interference detection accuracy deteriorates

Engineering Contradiction:

Improvechannel access procedureVSAvoidinterference detection accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent segments the channel access procedure into two independent parts: the simplified eNB-driven scheduling for data transmission and the distributed client-based interference detection for hidden terminal awareness. This segmentation allows each component to optimize for its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces client feedback messages as an intermediary mechanism. Clients report their channel state and interference experiences back to the eNB, which then uses this information to adjust scheduling decisions. This intermediary feedback loop enables the eNB to gain interference awareness without changing the fundamental eNB-driven access procedure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If LTE operates in unlicensed spectrum without interference awareness, then system complexity is reduced, but channel collision increases

Engineering Contradiction:

Improvesystem complexityVSAvoidchannel collision

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent implements self-service at the client level, where each client independently performs clear channel assessment and back-off procedures before transmitting. This distributed self-service approach enables clients to autonomously avoid collisions without requiring complex centralized coordination or extensive system modifications.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent establishes a feedback mechanism where clients report their channel access success or failure to the eNB. This feedback loop enables the eNB to learn from client experiences and adjust its scheduling to avoid collisions, gradually building interference awareness without requiring complete system redesign.

Inventive Principle:

Principle #23Feedback

3Device complexity

If LTE lacks visibility into channel state, then implementation is simpler, but spectrum utilization deteriorates

Engineering Contradiction:

Improveimplementation complexityVSAvoidspectrum utilization

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent applies partial action by having clients perform channel state reporting only when necessary (e.g., when data transmission occurs or channel conditions change). This selective reporting approach provides sufficient interference information for scheduling decisions without requiring continuous monitoring or complex implementation across all system components.

Inventive Principle:

Principle #16Partial or excessive action

4Loss of time

If traditional channel access is used, then measurement overhead is minimized, but throughput is limited

Engineering Contradiction:

Improvemeasurement overheadVSAvoidthroughput

Core Design Contradiction:

Loss of timeVSProductivity

Solution Approach 1:

The patent merges multiple functions into the existing client feedback mechanism: channel state reporting, interference measurement, and scheduling information are combined into a single feedback exchange. This integration allows the system to gather necessary measurements for throughput optimization without adding separate measurement procedures that would increase overhead.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS10469188B2System and method for enabling interference-awareness for LTE operation in unlicensed spectrum

Publication Date: 2019.11.05 NEC CORP

AI summary

A computer-implemented method executed on a processor for employing an epoch-based approach to estimating interference in an unlicensed spectrum is presented. The method includes enabling communication between a long-term evolution (LTE) evolved node B (eNodeB) and a plurality of clients, detecting and measuring the interference in all existing non-overlapping channels, via the LTE eNodeB, caused by one or more hidden clients of the plurality of clients, collecting interference statistics from all of the plurality of clients across all different channels, and leveraging interference-awareness resulting in channel access performance improvement at a macro-time scale and a micro-time scale.