Joint Access Point Selection in Multi-Hop Wireless Networks
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Solution Overview
Problem
Existing methods for selecting an access point or relay node in multi-hop wireless networks do not effectively consider both the path metric inside the network and the access link quality, leading to suboptimal communication performance.
Innovation Solution
An end device selects an access point or relay node based on a joint selection metric that combines the access link quality and the path quality from the access point or relay node to the gateway, using enhanced beacon and probe response frames to gather information and calculate the joint access point selection cost function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an end device selects an access point based only on received signal strength indicator (RSSI), then the access link quality is improved, but the overall communication performance deteriorates due to ignoring other factors such as AP load and path quality
Solution Approach 1:
The patent combines multiple selection metrics (access link quality measured by RSSI, AP load, and path quality) into a unified joint selection metric. This merging of previously separate considerations allows the end device to evaluate access points comprehensively, resolving the contradiction by ensuring that strong access links are paired with acceptable load conditions and path quality, thereby improving overall communication performance while maintaining reliable access.
2Quantity of substance
If an access point selection metric is based on the total number of users and average packet error rate, then the network load is considered, but the bandwidth contention among end devices and different link data rates are not captured
Solution Approach 1:
The patent introduces a refined measurement approach that changes the parameters used to evaluate AP selection. Instead of relying solely on the total number of users and average packet error rate, the invention incorporates end device-specific parameters including individual link data rates and bandwidth contention metrics. This parameter change enables more precise measurement of available bandwidth and contention levels, allowing end devices to make better-informed selection decisions that account for their specific transmission characteristics.
3Reliability
If a centralized method is used to determine end device-AP association to ensure network-wide max-min fair bandwidth allocation, then fairness is improved, but the system complexity increases due to requiring a central controller that knows the bandwidth of each end device
Solution Approach 1:
The patent implements a self-service mechanism where end devices autonomously perform AP selection without requiring a centralized controller. Each end device calculates its own joint selection metric using locally available information (RSSI, path quality) and broadcasts bandwidth information that other devices can use. This distributed self-service approach achieves fair bandwidth allocation through decentralized decision-making, eliminating the need for complex centralized control while maintaining network-wide fairness objectives.
4Ease of operation
If single-hop wireless network selection methods are used in multi-hop networks, then the implementation is simple, but the communication performance deteriorates because the path quality inside the network is not considered
Solution Approach 1:
The patent applies preliminary action by having access points pre-calculate and broadcast their path quality metrics to the gateway before end devices perform selection. This advance preparation of path quality information allows end devices to incorporate multi-hop path considerations into their selection decisions without adding complexity to the selection algorithm itself. The preliminary calculation and broadcasting of path metrics enables simple end device operations while achieving improved communication performance through informed selection based on complete path quality awareness.
Data Source
AI summary
A method and apparatus are described for selecting an access point in a wireless network, including initializing a channel index, recording a received signal power and information contained in one of a beacon message and a probe request response message, calculating an access link metric for each candidate access point, the access link 13 metric being between an end device and each candidate access point on the channel indexed by the channel index responsive to the received signal power and information receiving a path metric between each candidate access point and a gateway, estimating a function using the access link metric and the path metric, selecting one of the candidate access points based on the function and establishing a connection with the selected access point. Also described is a method and apparatus for maintaining a connection with an access point.