Cross-Layer Routing Metrics for Wireless Mesh Networks

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Solution Overview

Problem

Existing routing protocols in wireless mesh networks fail to maximize end-to-end throughput due to their reliance on simplistic metrics like hop count and signal-to-noise ratio, which do not account for congestion and interference, leading to performance degradation and inefficient route selection.

Innovation Solution

The solution involves combining link layer metrics, such as queued and transmitted packet delivery ratios, with network layer metrics like hop count to compute a routing metric that selects optimal routes by advertising a route cost and hop count, allowing routing nodes to choose parent nodes with reduced hop costs and congestion avoidance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If routing protocols use hop count as the routing metric, then routing decisions are simple and based on network layer information, but end-to-end throughput deteriorates due to congestion and interference not being considered

Engineering Contradiction:

Improverouting protocol complexityVSAvoidend-to-end throughput

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The patent merges network layer routing metrics (hop count) with link layer metrics (packet delivery ratio, queue depth) to create a composite routing metric. This combination allows the routing protocol to consider both simplicity and actual transmission quality, resolving the contradiction between protocol simplicity and throughput optimization.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent adds link layer dimensional information (packet delivery ratio, queue depth) to the traditional network layer routing decisions. By incorporating these additional dimensions of information, the system can make more informed routing decisions that account for congestion and interference while maintaining manageable protocol complexity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If routing protocols use signal-to-noise ratio (SNR) as the routing metric, then routes with higher SNR are selected, but inter-hop interference and congestion level are not accounted for

Engineering Contradiction:

Improvelink reliabilityVSAvoidend-to-end throughput

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent combines SNR-based link reliability metrics with congestion indicators (queue depth, packet delivery ratio) to create a comprehensive routing metric. This merging allows the system to select routes that are not only reliable but also avoid congested paths, thereby maximizing end-to-end throughput.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces intermediary metrics (packet delivery ratio, queue depth) that mediate between link layer reliability (SNR) and network layer routing decisions. These intermediary metrics provide a bridge that allows routing protocols to consider both reliability and congestion factors simultaneously.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If routing protocols combine SNR and hop count, then routing decisions consider multiple factors, but the combination still does not solve congestion and interference problems

Engineering Contradiction:

Improverouting metric comprehensivenessVSAvoidend-to-end throughput

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The patent changes the parameters used in routing decisions from simple hop count or SNR to more comprehensive metrics including packet delivery ratio and queue depth. By changing these parameters to better reflect actual network conditions, the system can adapt to congestion and interference dynamics, thereby improving throughput.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback mechanisms where routing nodes continuously monitor packet delivery ratios and queue depths, and use this feedback to dynamically adjust routing decisions. This feedback loop allows the system to respond to changing congestion conditions and optimize throughput in real-time.

Inventive Principle:

Principle #23Feedback

4Ease of manufacture

If routing decisions are based on approximate SNR thresholds, then implementation is simplified, but packet delivery probability prediction becomes inaccurate

Engineering Contradiction:

Improveprotocol implementation easeVSAvoidpacket delivery probability prediction

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent replaces simple threshold-based SNR comparison with more sophisticated packet delivery ratio measurement and routing metric calculation. This substitution maintains implementation feasibility while significantly improving the accuracy of packet delivery probability prediction through direct measurement of actual delivery outcomes.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS7936681B2Cross-layer design techniques for interference-aware routing configuration in wireless mesh networks

Publication Date: 2011.05.03 CISCO TECHNOLOGY INC

AI summary

Methods, apparatuses and systems directed to facilitating increased throughput in wireless mesh networks. Generally, according to one implementation of the present invention, routing nodes in a wireless mesh network combine metrics corresponding to the link and network layers to select a route to a root node in the wireless mesh network. In one implementation, for each neighbor, a given routing node computes a routing metric, which is based on the computed route cost and hop count, and selects a preferred neighbor as the parent routing node based on the best routing metric.