Analysis of Routing Metrics for Wireless Mesh Networks To build Wireless Mesh Network To Investigate wireless link characteristics Whether link abstraction exists? What is the effect of interference? To Implement of ETT inside ‘OLSRD’ To analyze ETX and ETT What is the end-end delay, throughput? What is the effect of bandwidth? How interference plays its role here?

Accomplishments and Contributions There exists a considerable correlation between packet error rate and received signal strength. We attribute the high error rate to external interference. ETT outperforms ETX. Unless, the bandwidth of a path compensates for the interference effect, ETT chooses the same path as that of ETX. Characterization of a wireless link Implementation of ETT in ‘OLSRD’ Analysis of metrics in terms of delay, throughput and paths taken Effect of interference on ETT and ETX

Architecture

Network set up Transmit Power Transmit Rate Number of packets to send Duration of experiment Received Signal Strength at the receiver External Interference at the receiver Enabling IP forwarding Source of external interference Metrics (delay, throughput) for analysis

Link Layer Abstraction There exists a considerable correlation between packet error rate and received signal strength. We attribute the high error rate to external interference.

Effect of packet size With increase in packet size, the probability of packet being corrupted increases.

Routing metrics : Delay and Throughput ETT outperforms ETX in terms of delay and throughput given the same networking scenario.

Convergence of routing metrics ETT value takes into consideration the bandwidth and thus is able to identify the lower expected transmission time link.

Paths taken by routing metrics Packets get routed through intermediate node operating at 5.5Mbps taking advantage of ETT which considers bandwidth to calculate metric value. Unless, bandwidth compensates of interference ETT ends up choosing the same hop as ETX.

Lessons learnt and Future Work Taking wireless measurements is non-trivial job. Hands on experience of handling wireless devices and tools More number of hops WCETT and interference aware routing Deployment and applications

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