Node Rank Determination in Multi-Hop Wireless Networks
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Solution Overview
Problem
In wireless mesh networks, especially in smart grid systems, the instability of wireless links due to fading effects and interference poses challenges for reliable and low-latency data routing, requiring intelligent routing protocols that can adapt to link state changes while maintaining simplicity and flexibility.
Innovation Solution
A DAG-based routing protocol is implemented, which includes a novel rank-determination method and a reverse path recording mechanism to establish reliable paths for both inward and outward traffic, allowing the network to quickly adapt to link instability and maintain efficient data transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DAG-based routing protocol is used to handle link instability, then reliability of data transmission is improved, but computational complexity for rank determination increases
Solution Approach 1:
The patent changes the parameter used for rank determination from complex multi-metric calculations to a simplified single-parameter approach based on Expected Transmission Time (ETX). Each node calculates its rank as R(i) = R(p(i)) + ETX(i, p(i)), where only the ETX of the direct link to parent needs to be computed, significantly reducing computational complexity while maintaining routing reliability
Solution Approach 2:
The patent segments the complex routing decision into two independent components: (1) ETX calculation for link quality assessment, and (2) rank determination based on parent node rank plus ETX. This segmentation allows each component to be computed separately and efficiently, reducing overall computational burden
2Adaptability or versatility
If rank determination based on ETX is implemented, then adaptability to link state changes is improved, but transmission time for rank updates increases
Solution Approach 1:
The patent implements periodic rank update mechanisms where nodes exchange DIO (DAG Information Object) messages at regular intervals to update their ranks based on current ETX measurements. This periodic action ensures the network adapts to link state changes while maintaining a predictable and manageable update schedule that prevents excessive transmission overhead
Solution Approach 2:
The patent uses feedback mechanisms where nodes continuously monitor link quality (ETX) and adjust their ranks accordingly. When ETX changes indicate significant link state changes, nodes trigger rank recalculation and propagate updates through the network, ensuring adaptability while avoiding unnecessary updates during stable conditions
Data Source
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AI summary
Embodiments of the invention disclose a system and a method for determining a rank of a node in a multi-hop wireless network, wherein the network includes a gateway node, client nodes, and relay nodes, wherein a node p(i) is a default parent of the node i having a rank, and the network uses a directed acyclic graph (DAG) topology. The method comprises steps of transmitting at least one data packet from the node to the default parent node over a wireless link; counting a number of successful transmissions of most recent transmissions of data packets; determining an expected transmission time (ETX) for the wireless link based on the number of successful transmissions in the most recent transmissions; and assigning a rank R(i) to the node based on the rank of the parent node and the ETX.