PoE Classification Using Selective Frequency Filtering

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Current Power over Ethernet (PoE) standards, such as IEEE 802.3af and 802.3-2005, have limitations in classifying powered devices (PDs) due to their reliance on DC voltage detection and classification methods, which are not sufficient for accurately determining the power requirements of advanced devices, leading to inefficient power allocation.

Innovation Solution

A new classification technique using selective frequency filtering, where a power-sourcing equipment (PSE) provides an electronic signal with multiple frequency components over a wire, and the PD selectively filters these components to classify itself into one of several classes, allowing for more precise power allocation based on the pattern of frequency components present.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If DC voltage detection and classification methods are used, then compatibility with existing PoE standards is maintained, but the number of definable power classes is limited to 5

Engineering Contradiction:

Improvenumber of power classesVSAvoidclassification method complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the classification parameter from DC voltage levels to AC frequency components. By injecting AC signals at different frequencies and detecting which frequencies are present or suppressed in the response, the system can identify many more unique patterns, thereby increasing the number of definable power classes from 5 to potentially 24 or more.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent transitions from a one-dimensional classification (single DC voltage level) to a multi-dimensional classification system using multiple AC frequency components. This allows the system to encode more information in the classification signal, enabling differentiation among many more device classes while maintaining backward compatibility through optional use of both DC and AC methods.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If repetitive classification processes are used, then additional power classes can be detected, but the classification time and power consumption increase

Engineering Contradiction:

Improvepower class detection capabilityVSAvoidclassification time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent employs periodic AC signals at specific frequencies for classification. By using predetermined frequency components and detecting their presence or suppression in the device response, the system can perform comprehensive classification in a single periodic cycle rather than requiring multiple repetitive DC voltage applications, thus reducing classification time while maintaining or enhancing detection capability.

Inventive Principle:

Principle #19Periodic action

3Adaptability or versatility

If more frequency components are used for classification, then more power classes can be defined, but the signal processing complexity increases

Engineering Contradiction:

Improvenumber of power classesVSAvoidfrequency component detection complexity

Core Design Contradiction:

Adaptability or versatilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent segments the frequency spectrum into distinct, non-overlapping frequency components. Each frequency component can be detected independently using simple bandpass filters or frequency-selective circuits. This segmentation approach allows multiple frequency components to be processed in parallel with relatively simple circuitry, avoiding the need for complex simultaneous multi-frequency analysis.

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This technique enables more precise classification of PDs, potentially increasing the number of definable classes from 5 to 24 or more, improving power allocation efficiency and compatibility with newer standards like PoE+, by using frequency components to determine the power class of devices connected to the network.

Implementation Method 1

a powered device (PD) selectively filters the signal to classify itself into one of several classes according to a pattern of frequency components present

Methodology Applied

Scientific EffectSelective frequency filtering: Filter (electronic)

Data Source

PatentUS7873845B2Classification technique for powered devices using selective frequency filtering

Publication Date: 2011.01.18 CISCO TECHNOLOGY INC

AI summary

A method, performed by a power sourcing apparatus is provided. The method includes (a) providing an electronic signal to a powered device (PD) over a wire through a circuit device, the circuit device permitting current to flow at pre-determined frequencies, the pre-determined frequencies forming a first set of frequency components, (b) sensing the electronic signal over the wire to detect frequency components present in the electronic signal, the detected frequency components forming a second set of frequency components, and (c) classifying the electronic signal into one of a plurality of classes according to a pattern of frequency components present in the first and second sets. Apparatus for use in conjunction with the method are also provided.