Multi-mode Dynamic Frequency Selection for Wireless Mesh Networks
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Solution Overview
Problem
Wireless mesh networks in environments with limited broadband Internet infrastructure face challenges in dynamic frequency selection (DFS) due to radar interference, leading to false detection issues and disruptions, especially in crowded areas like buildings, where inner nodes frequently detect radar events inaccurately.
Innovation Solution
Implementing a multi-mode frequency selection system where cloud servers assign WAP devices as primary or secondary based on their location and directional antenna orientation to optimize DFS functionality, reducing false detections and channel switching latency by designating edge nodes as primary DFS owners and inner nodes as secondary, and utilizing a channel preference list for swift channel changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all WAP devices perform DFS detection independently, then radar detection coverage is improved, but false detection rate increases due to inner nodes detecting radar events inaccurately
Solution Approach 1:
The patent segments the WAP network into two functional groups: edge WAPs that perform DFS detection and inner WAPs that do not. This segmentation resolves the contradiction by assigning detection responsibilities only to edge nodes where radar detection is accurate, while inner nodes focus on client service, eliminating their false detections.
Solution Approach 2:
The patent introduces a controller as an intermediary that coordinates DFS operations. The controller receives radar detection information from edge WAPs, determines whether radar events are genuine or false, and manages channel switching decisions. This intermediary layer prevents false detections from inner nodes while maintaining accurate radar detection capabilities.
2Object-affected harmful factors
If WAP devices frequently switch channels due to radar detection, then interference avoidance is improved, but network disruption increases due to false positives
Solution Approach 1:
By segmenting DFS detection responsibilities to only edge WAPs, the system avoids false radar detections from inner nodes that would trigger unnecessary channel switches. This maintains network stability while still providing radar interference avoidance through accurate edge node detection.
Solution Approach 2:
The patent implements a feedback mechanism where edge WAPs report radar detection information to a controller, which then verifies the authenticity of radar events before triggering channel switches. This feedback loop prevents false positives from causing unnecessary network disruptions while maintaining responsive radar interference avoidance.
3Adaptability or versatility
If inner nodes are designated as primary DFS owners, then DFS capability is distributed, but false radar events increase due to their location in crowded areas
Solution Approach 1:
The patent inverts the conventional approach by designating edge WAPs (rather than inner nodes) as primary DFS owners. This inversion leverages the fact that edge nodes have better radar detection accuracy due to their location, while still maintaining DFS capability distribution across the network through the controller's coordination.
4Speed
If channel switching is performed rapidly in response to radar events, then interference avoidance speed is improved, but channel switching latency increases due to coordination overhead
Solution Approach 1:
The patent implements preliminary action by having edge WAPs continuously monitor for radar events and pre-identify alternative channels. When radar is detected, the controller can quickly coordinate channel switching using pre-prepared information, reducing the actual switching latency while maintaining fast interference avoidance response.
Data Source
AI summary
A wireless mesh network includes a first wireless access point (WAP) device designated as a primary device, where the first WAP device provides network connectivity to a plurality of client devices over a first dynamic frequency selection (DFS) channel. A second WAP device is designated as a secondary device to the first WAP device on the first DFS channel. In response to detection of a radar event by the first WAP device: the first WAP device transitions to being the secondary device on the first DFS channel; the second WAP device transitions to being the primary device on the first DFS channel; and the second WAP device performs a channel availability check (CAC) on a second DFS channel and communicates availability of the second DFS channel to the first WAP device.