Date of Final Oral Examination (Defense)

8-2012

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Computer Science

Department

Computer Science

Major Advisor

Murali Medidi, Ph.D.

Abstract

Wireless Sensor Networks (WSNs) are employed for either continuous monitoring or event detection in the target area of interest. In event-driven applications, it is critical to report the detected events in the area, and with sudden bursts of traffic possible due to spatially-correlated events or multiple events, the data loss due to congestion will result in information loss or delayed arrival of the sensed information. Congestion control techniques detect congestion and attempt to recover from packet losses due to congestion, but they cannot eliminate or prevent the occurrence of congestion. Congestion avoidance techniques employ proactive measures to alleviate future congestion using parameters like queue length, hop count, channel conditions, and priority index. However, maintaining and processing such information becomes a significant overhead for the sensor nodes and degrades the performance of the network. We propose a congestion avoidance MAC protocol that uses the queue buffer length of the sensor nodes to estimate the congestion and diffuse traffic to provide a congestion-free routing path towards the base station. This protocol provides event reporting, packet delivery ratio, by dynamically diffusing the traffic in the network using multiple forwarders in addition to backup forwarding. We used the standard Network Simulator (NS2) to evaluate the performance of our protocol. Results show that our protocol significantly improves event reporting in terms of packet delivery ratio, throughput, and delay by avoiding congestion while diffusing the traffic effectively.

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