Dynamic Subcarrier Utilization in OFDM Networks

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Solution Overview

Problem

Current OFDM-based communication networks in Low Power and Lossy Networks (LLNs) face challenges such as low throughput and limited spectral efficiency due to the selection and allocation of subcarriers, which are not optimized based on current transmission activity, leading to inefficient use of bandwidth and increased latency.

Innovation Solution

The proposed solution involves monitoring and dynamically adjusting subcarrier utilization based on current transmission activity, allowing for simultaneous transmissions on unused subcarriers, and intelligently scheduling transmissions to optimize network performance, thereby treating the OFDM channel as multiple independent channels rather than a single channel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If OFDM transmits multiple data streams across orthogonal subcarriers simultaneously, then throughput increases, but spectral efficiency deteriorates due to non-optimized subcarrier selection and allocation

Engineering Contradiction:
ImprovethroughputVSAvoidspectral efficiency
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The patent implements dynamic subcarrier selection and allocation that adapts to current transmission activity. The system continuously monitors which subcarriers are currently in use and dynamically adjusts the set of active subcarriers based on real-time network conditions, transforming the static subcarrier allocation into a dynamic, adaptive process that optimizes both throughput and spectral efficiency

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the parameter of subcarrier utilization by treating the OFDM channel as multiple independent channels rather than a single channel. This parameter change enables selective activation of subcarriers based on current transmission activity, allowing the system to optimize spectral efficiency while maintaining high throughput through intelligent subcarrier management

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If subcarrier selection is not optimized based on current transmission activity, then device complexity is reduced, but latency increases due to inefficient bandwidth use

Engineering Contradiction:
Improvesubcarrier selection complexityVSAvoidlatency
Core Design Contradiction:
Device complexityVSLoss of time

Solution Approach 1:

The patent implements a feedback mechanism where the system monitors current transmission activity on subcarriers and uses this information to intelligently schedule future transmissions. This feedback loop enables the system to make informed decisions about subcarrier allocation, reducing latency by avoiding collisions and optimizing bandwidth utilization without requiring complex centralized control

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system enables subcarriers to effectively self-manage by allowing devices to independently identify and utilize unused subcarriers for simultaneous transmissions. This self-service approach reduces the need for complex centralized scheduling while minimizing latency through efficient, distributed subcarrier selection based on real-time channel conditions

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP2829032B1Dynamic subcarrier utilization and intelligent transmission scheduling
Publication Date: 2020.08.26 CISCO TECHNOLOGY INC
  • EP2829032B1 patent drawingFigure 1
  • EP2829032B1 patent drawingFigure 2
  • EP2829032B1 patent drawingFigure 3

AI summary

In one embodiment, a transmitting device monitors transmission activity of each of a plurality of subcarriers in a communication network, and determines a set of unutilized subcarriers of the plurality of subcarriers. As such, the transmitting device may then transmit a data frame on one or more of the unutilized subcarriers to a receiving device while transmission activity is present on one or more utilized subcarriers within the network. In another embodiment, the transmitting device may also determine timing information associated with the transmission activity, and may correspondingly schedule the transmitting to optimize network performance based on the timing information.