Wireless Mesh Path Selection Using Link Layer Metrics
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Solution Overview
Problem
Conventional wireless mesh network protocols fail to efficiently select the optimal path to a mesh portal due to reliance on signal strength, which does not directly correlate with actual transmission success, leading to suboptimal data forwarding and potential collisions.
Innovation Solution
Each mesh point generates an ordered group of parent access points based on link layer metrics, assigning priority and minimum interframe spacing to ensure that the parent with the optimum metric for reaching the mesh portal forwards packets, even if it has a lower probability of receiving them, thereby implementing a directed acyclic graph and priority-based access protocol.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If mesh points select parent access points based on signal strength, then the selection process is simple, but the path to mesh portal is suboptimal and transmission success is reduced
Solution Approach 1:
The patent changes the selection parameter from signal strength to link layer metrics that directly correlate with transmission success. Mesh points evaluate parents based on metrics such as forward error correction capability, modulation scheme, and signal-to-noise ratio, which are more reliable indicators of actual transmission performance than raw signal strength alone.
Solution Approach 2:
The patent replaces the simple signal strength comparison mechanism with a more sophisticated evaluation system that uses link layer metrics. This substitution involves implementing a metric calculation module that processes multiple parameters (FEC capability, modulation type, SNR) to generate a comprehensive quality score for each potential parent access point.
2Reliability
If mesh points prioritize parents with highest reception probability, then packet reception is maximized, but path latency increases and optimal forwarding path is not used
Solution Approach 1:
The patent implements dynamic parent selection where mesh points can switch between different parent access points based on current network conditions and metric evaluations. The system maintains multiple parent candidates and dynamically selects the optimal parent for each packet transmission, allowing flexibility to balance reception probability and latency requirements.
Solution Approach 2:
The patent performs preliminary metric evaluation and parent ordering before actual data transmission. Mesh points pre-calculate and sort potential parent access points based on link layer metrics, establishing an ordered list of candidates. This preliminary action enables quick selection of optimal parents during transmission without real-time calculation delays.
3Reliability
If multiple parents forward packets simultaneously, then redundancy is increased, but collisions increase and network efficiency decreases
Solution Approach 1:
The patent segments the packet forwarding function across multiple parents with differentiated roles. The primary parent (highest metric) handles most forwarding, while secondary parents (lower metrics) provide optional redundancy only when the primary parent is unavailable or experiences failures. This segmentation reduces simultaneous transmissions and associated collisions while maintaining necessary redundancy.
Data Source
AI summary
In one embodiment, a method includes a mesh point receiving mesh advertisement messages from advertising mesh points of a wireless mesh network having a mesh portal with a wired connection to a wired network. Each mesh advertisement message specifies a corresponding metric for reaching the mesh portal and has a corresponding signal strength indicator. An ordered group of parent access points, ordered based on the respective metrics, is generated from among the advertising mesh points, starting with a first parent access point having a corresponding optimum metric for reaching the mesh portal and independent of the corresponding signal strength indicator. A registration message is sent to each of the parent access points identifying a corresponding specified priority based on a corresponding position in the ordered group, for use by the corresponding parent access point in selecting a minimum interframe spacing for forwarding a wireless packet received from the mesh point.