Wireless LAN Scanning Method Using Probe Frame Merging
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Solution Overview
Problem
Existing WLAN technologies face challenges in rapid initial link setup times due to lengthy Medium Access Control (MAC) procedures, particularly in wide-area WLANs, which hinder the efficient access of Stations (STAs) to Access Points (APs).
Innovation Solution
The proposed scanning method involves an AP receiving a probe request frame from a STA, unicasting a probe response frame, and starting a timer, allowing for efficient broadcasting or unicasting of subsequent probe response frames based on a timer or specific time intervals, optimizing the scanning process by reducing overhead and increasing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional active scanning is used in WLAN, then STAs can discover APs, but the initial link setup time becomes very long
Solution Approach 1:
The patent combines active scanning and passive scanning operations into a unified process. The AP responds to probe requests from multiple STAs using a single broadcast probe response frame that contains information for multiple STAs simultaneously, merging what would traditionally be separate unicast responses into one efficient operation.
Solution Approach 2:
The patent implements preliminary actions by having the AP maintain a list of STAs that have sent probe requests and prepare broadcast probe response frames in advance. The AP starts a timer upon receiving the first probe request and prepares to send consolidated responses before all STAs have necessarily transmitted their requests, reducing overall setup time.
2Ease of operation
If the AP unicasts probe response frames to each STA individually, then each STA receives its response, but the overhead and time consumption increase
Solution Approach 1:
The patent merges multiple unicast probe response operations into a single broadcast operation. The AP sends one probe response frame that contains service set identification information and other relevant data that can be used by multiple STAs simultaneously, eliminating the need for separate unicast transmissions to each STA.
Solution Approach 2:
The broadcast probe response frame serves multiple functions and multiple STAs simultaneously. A single frame transmission provides response information to all STAs in the active scanning list, making the response mechanism universal rather than individual-specific, thereby reducing overhead and time consumption.
3Productivity
If the AP broadcasts probe response frames to all STAs, then the response reaches multiple STAs efficiently, but unnecessary frames are transmitted to STAs not in the scanning list
Solution Approach 1:
The patent applies local quality by differentiating the response method based on the specific STA and its state. The AP unicasts probe responses to STAs that are in the active scanning list while using broadcast for consolidated responses to multiple STAs simultaneously. This localized approach ensures that each STA receives appropriate responses without unnecessary transmissions to STAs not involved in scanning.
Solution Approach 2:
The patent implements dynamic response behavior where the AP adjusts its scanning response strategy based on real-time conditions. The AP maintains a dynamic list of STAs in active scanning state and uses timers to manage the scanning process, switching between unicast and broadcast modes depending on the number of STAs and their scanning status, thereby optimizing energy efficiency.
Data Source
AI summary
Disclosed are a scanning method and scanning apparatus in a wireless LAN. The scanning method in a wireless LAN comprises: a step in which an access point (AP) receives a first probe request frame from a first station (STA); a step in which the AP unicasts a first probe response frame to the first STA as a response to the first probe request frame; a step in which the AP receives a second probe request frame from a second STA for a specific time interval after unicasting the first probe response frame to the first STA; and a step in which the AP broadcasts a second probe response frame as a response to the second probe request frame for a specific time interval. Thus, scanning processes can be quickly performed.