Access Point Probe Requests for Handover Control
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Solution Overview
Problem
Current mobile communication networks face challenges in efficiently managing handovers between access points, leading to uneven load distribution, poor association decisions based on fixed attributes, and lack of network control over the association process, resulting in suboptimal quality of service and increased costs due to the need for dedicated hardware for link quality assessment.
Innovation Solution
The method allows network operators to control the association and handover process between mobile terminals and access points by enabling access points to perform off-channel link quality assessments, using probe requests and responses to determine connection quality, and selectively accept or reject association requests, thereby optimizing load balancing and quality of service without modifying existing mobile equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If access points use fixed attributes for association decisions, then the association process is simple, but the quality of service is suboptimal
Solution Approach 1:
The patent performs link quality assessments before the actual handover occurs. Access points conduct probe requests and evaluate connection quality metrics in advance, so that when handover is needed, the decision is already based on pre-collected data about neighboring access points' link qualities, eliminating the need for complex real-time evaluations during handover
Solution Approach 2:
The patent introduces an intermediary assessment mechanism where access points send probe requests to mobile terminals and evaluate the responses to determine link quality. This intermediary process provides objective quality metrics that mediate between simple association rules and complex quality requirements, enabling better service quality without proportionally increasing complexity
2Productivity
If mobile terminals autonomously select access points based on signal strength, then the association process is fast, but the load distribution is uneven
Solution Approach 1:
The patent implements feedback mechanisms where access points monitor link quality metrics and use this information to control whether they accept or reject association requests. The system feedback loop includes measuring RSSI, evaluating link quality, and adjusting acceptance decisions accordingly, enabling load balancing while maintaining fast association through predefined acceptance/rejection rules
Solution Approach 2:
The patent changes the decision parameter from simple signal strength threshold to a composite link quality assessment that includes RSSI, interference levels, and current load conditions. By modifying the parameters used for acceptance decisions, the system achieves better load distribution without significantly impacting association speed, as the evaluation is based on pre-measured parameters
3Measurement precision
If dedicated hardware is used for link quality assessment, then the measurement precision is high, but the system cost increases
Solution Approach 1:
The patent uses software-based probe request mechanisms that replicate the functionality of dedicated hardware assessment tools. Instead of requiring specialized hardware, the system uses standard wireless communication protocols to send probe requests and measure link quality, creating a software copy of hardware assessment capabilities that achieves sufficient precision without additional hardware costs
Solution Approach 2:
The patent makes existing wireless communication interfaces multi-functional by using them for both data transmission and link quality assessment. The same wireless interface that handles normal communication also performs probe requests, RSSI measurements, and link quality evaluations, eliminating the need for dedicated assessment hardware while maintaining measurement precision through software control
4Object-generated harmful factors
If access points operate on different non-overlapping channels, then interference between access points is minimized, but the handover control capability is reduced
Solution Approach 1:
The patent performs link quality assessments on the current operating channel before handover is initiated. By measuring RSSI and evaluating link quality in advance on the existing channel, the system maintains control capability without requiring channel switching for assessment, thus preserving both interference avoidance and automation capability
Data Source
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AI summary
In a wireless communication system comprising a mobile terminal and at least two access points, each access point is adapted to provide data communication with the mobile terminal within a service area of the access point through a wireless interface over a selected one of a number of channels. A method of controlling selection of an access point comprises controlling one or more further access points having service areas adjacent or overlapping with a service area of a first access point, to which a first mobile terminal is associated, to send probe request messages to the first mobile terminal, and determining, for each of the one or more further access points and from a response received from the first mobile terminal in response to the corresponding probe request message, a respective first value representing a quality of a connection between the respective access point and the first mobile terminal. Selected ones of the one or more further access points are controlled to accept a future association request from the first mobile terminal, while the not selected access points are controlled to reject a future association request from the mobile terminal.