Puncturing Radar in Wide DFS Channels

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Solution Overview

Problem

Wireless access points (APs) operating in Dynamic Frequency Selection (DFS) channels face inefficiencies in spectrum utilization when detecting radar signals, as existing methods either switch to different channels or lower bandwidth, leading to suboptimal use of large bandwidths, and legacy client devices may not support puncturing processes, potentially violating regulatory requirements due to poor filtering.

Innovation Solution

The AP classifies client devices' filtering quality and maintains service for both puncturing-capable and incapable devices by utilizing puncturing to avoid radar collisions, allowing eligible devices to use the full bandwidth while steering ineligible devices to smaller subsets, and announcing suitable bandwidths based on client capabilities and filtering qualities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the AP switches to a different channel when radar is detected, then radar interference is avoided, but spectrum utilization efficiency deteriorates due to loss of the entire channel bandwidth

Engineering Contradiction:
Improveradar interference avoidanceVSAvoidspectrum utilization efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent segments the 160 MHz channel into multiple 20 MHz sub-channels. When radar is detected in one sub-channel, only that specific sub-channel is avoided while other sub-channels continue to operate, thereby maintaining high spectrum utilization efficiency while avoiding radar interference.

Inventive Principle:
Principle #1Segmentation

2Reliability

If the AP lowers bandwidth to avoid radar, then radar collision is avoided, but spectrum utilization efficiency deteriorates due to reduced bandwidth usage

Engineering Contradiction:
Improveradar collision avoidanceVSAvoidspectrum utilization efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies local quality by treating different sub-channels differently based on radar detection results. Sub-channels without radar interference maintain full bandwidth operation, while only the specific sub-channel with radar interference is excluded, optimizing local spectrum usage rather than reducing overall bandwidth.

Inventive Principle:
Principle #3Local quality

3Productivity

If the AP uses puncturing to avoid radar in specific sub-channels, then spectrum utilization efficiency improves, but device complexity increases due to need to classify client device capabilities

Engineering Contradiction:
Improvespectrum utilization efficiencyVSAvoidclient device classification complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent performs preliminary classification of client devices during the association phase, before radar detection occurs. This preliminary action stores capability information that can be quickly referenced later when radar is detected, avoiding the need for complex real-time classification and reducing overall system complexity.

Inventive Principle:
Principle #10Preliminary action

4Reliability

If the AP steers ineligible devices to smaller bandwidth subsets, then regulatory compliance is maintained for legacy devices, but spectrum utilization efficiency deteriorates due to underutilization of available bandwidth

Engineering Contradiction:
Improveregulatory complianceVSAvoidspectrum utilization efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent segments the client device population into eligible and ineligible groups based on puncturing capability. Eligible devices can utilize the full available bandwidth excluding radar-affected sub-channels, while ineligible devices are assigned to appropriate smaller bandwidth subsets, optimizing spectrum usage for each device type according to its capabilities.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP3821631B1Bypassing radar in wide dynamic frequency selection (DFS) channels utilizing puncturing
Publication Date: 2024.09.18 CISCO TECHNOLOGY INC
  • EP3821631B1 patent drawingFigure 1
  • EP3821631B1 patent drawingFigure 2
  • EP3821631B1 patent drawingFigure 3

AI summary

Bypassing radar in wide Dynamic Frequency Selection (DFS) channels utilizing puncturing may be provided. A first client device may be classified as eligible for puncturing and a second client device may be classified as not eligible for puncturing. Next, it may be determined that a subchannel in a bandwidth range should not be used. Then, in response to determining that the subchannel in the bandwidth range should not be used, the first client device may be steered to a first subset of the bandwidth range and the second client device may be steered to a second subset of the bandwidth range. The second subset of the bandwidth range may be smaller than the first subset of the bandwidth range.