Access Controller Roaming Mechanism for WLAN Load Balancing
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Solution Overview
Problem
In Wireless Local Area Networks (WLANs), load balancing between access points is challenging due to uneven distribution of connected Stations (STAs), leading to insufficient bandwidth for heavily connected APs and idle resources on less connected APs, with STAs not actively roaming to adjacent APs with better signal strength unless the original AP's signal is weak.
Innovation Solution
A method where an Access Controller determines and switches STAs from overloaded APs to underloaded adjacent APs by channel switching, ensuring better signal strength and load balancing without disrupting communication, by using conditions such as set thresholds for STA numbers and load averages, and managing channel switching through specific packets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If STAs remain connected to their original AP even when adjacent APs have better signal strength, then connection stability is maintained, but load balancing deteriorates and bandwidth resources become insufficient for heavily connected APs
Solution Approach 1:
The system implements feedback mechanisms where APs continuously monitor their load status and STA connection information. When an AP becomes overloaded, it sends load adjustment indication information to the AC, which then coordinates with the STA to initiate roaming to a less loaded AP. This closed-loop feedback ensures connection stability is maintained while dynamically optimizing bandwidth resource utilization across the network.
Solution Approach 2:
The Access Controller (AC) serves as an intermediary between STAs and APs in the roaming process. Rather than allowing direct STA-to-AP roaming decisions, the AC receives load information from APs, determines optimal roaming targets, and controls the handover process. This intermediary coordination ensures that STAs roam to appropriate APs for load balancing while maintaining connection stability through controlled transitions.
2Productivity
If STAs actively roam to adjacent APs with better signal strength, then load balancing improves, but communication disruption occurs during the switching process
Solution Approach 1:
The system performs preliminary actions by establishing the air interface connection between the STA and the target AP before the source AP releases the STA. The AC controls the target AP to pre-establish connectivity, ensuring that when the STA switches channels, communication continues without interruption. This preliminary connection setup prevents communication gaps during roaming.
Solution Approach 2:
The roaming process is designed to maintain continuous useful action by ensuring data transmission can proceed through the target AP even before the STA fully completes the switching process. The source AP continues forwarding data to the target AP, and the STA can begin receiving data on the new channel while still maintaining logical connection continuity, thus eliminating communication disruptions.
3Measurement precision
If manual intervention is used for STA roaming decisions, then roaming accuracy improves, but system complexity and operational overhead increase
Solution Approach 1:
The system implements self-service by enabling APs to autonomously monitor their own load status and automatically send load adjustment indications to the AC when thresholds are exceeded. The AC then automatically determines roaming decisions and controls the handover process without manual intervention. This automation maintains high roaming decision accuracy while significantly reducing system operational complexity and human overhead.
Data Source
Figure 1~2A
Figure 2B~2C
Figure 3~4
AI summary
A method and a device for roaming a wireless STA are provided. The method and the device may be applied to an access controller (AC) in a wireless local area network. According to an example of the method, an STA of interest to be roamed from a first Access Point (AP) to a second AP is determined and the STA of interest is roamed from the first AP to the second AP by controlling the STA of interest to be switched from a working channel of the first AP to a working channel of the second AP.