# University of Houston

## Department of Computer Science

In Partial Fulfillment of the Requirements for the Degree of

Doctor of Philosophy

## Oluwasoji O. Omiwade

Will defend his dissertation

## Data Recovery in Wireless Sensor Networks

#### Abstract

Prior to uploading sensed data to a sink, nodes in a wireless sensor
network can store any one locally sensed data using robust distributed
storage solutions. A variety of replication and erasure coding methods
exist to store data in such systems so that when a subset of nodes in
the system fails, the original data can still be reconstructed from
live nodes. Our work concerns data recovery with minimal energy costs
as nodes fail in an unknown sequence. In particular, we propose
algorithms to maximize the network recovery capacity--the total number
of successful data recoveries until an insufficient number of nodes
exist to reconstruct the original data. We propose an online
polynomial-time algorithm, RECO that is within a constant
approximation ratio of the optimal oracle algorithm having complete
knowledge of failures patterns. Then we propose a more
computation-efficient polynomial-time algorithm, THAM, that with a
constant approximation ratio in acyclic networks. Our simulation
results show that THAM performs well even in general networks.

**Date:** Friday, July 29, 2011

**Time:** 11:00 AM

**Place:** 376-PGH

Faculty, students, and the general public are invited.

Advisor: Prof. Rong Zheng