Access Point Channel Indication for DFS Scanning Success
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Solution Overview
Problem
Wireless local area network (WLAN) devices face challenges in scanning dynamic frequency selection (DFS) channels due to failed channel availability checks (CAC), leading to wasted air interface resources and reduced scanning success rates.
Innovation Solution
A method where an access point sends channel information to a station indicating whether a neighboring access point successfully performs CAC on a DFS channel, allowing the station to switch and scan only if the CAC is successful, thereby avoiding resource waste and improving scanning efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the STA scans DFS channels without CAC status information, then the STA may discover more channels, but the STA wastes air interface resources by switching to channels where CAC fails
Solution Approach 1:
The patent applies preliminary action by having the AP perform CAC before the STA scans the DFS channel. The AP sends channel information including CAC status to the STA in advance, so the STA only switches to channels where CAC has already succeeded, avoiding wasted scanning attempts on unavailable channels.
2Adaptability or versatility
If the STA switches to DFS channels for scanning, then the STA can find better APs, but the STA increases dwell time on channels that may fail CAC
Solution Approach 1:
The AP performs CAC in advance before the STA switches to the DFS channel for scanning. By providing CAC status information beforehand, the STA avoids unnecessary channel switching and dwell time on channels that would fail CAC, thus reducing overall time loss while maintaining adaptability.
3Adaptability or versatility
If the STA scans all available channels including DFS, then the STA has more options for AP selection, but the STA experiences frame freezing during unsuccessful scans
Solution Approach 1:
The patent resolves frame freezing by having the AP complete CAC before the STA scans DFS channels. The AP sends channel information with CAC status to the STA, ensuring that the STA only switches to channels confirmed to be radar-free, thus eliminating frame freezing caused by unsuccessful CAC during scanning.
Data Source
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AI summary
A channel indication sending method, a channel scanning method, and an apparatus are disclosed. The sending method includes: A first access point receives channel information from a second access point, where the channel information indicates that an operating channel of the second access point is a first channel, and whether the second access point successfully performs channel availability check (CAC) on the first channel, and the first channel is a dynamic frequency selection (DFS) channel. The first access point sends, on a second channel, a WLAN frame to a station associated with the first access point, where the WLAN frame includes an indication about the first channel and an indication of whether the second access point successfully performs the CAC on the first channel. In this method, the first access point sends, to the station associated with the first access point, the indication of whether the CAC succeeds. In this case, the station switches, only after determining that the second access point successfully performs the CAC, to the DFS channel on which the second access point is located. This ensures a success rate of scanning the switched-to DFS channel by the station.