
<oai_dc:dc xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:oai_dc="http://www.openarchives.org/OAI/2.0/oai_dc/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://www.openarchives.org/OAI/2.0/oai_dc/ http://www.openarchives.org/OAI/2.0/oai_dc.xsd">
  <dc:title>COVERAGE AND CONNECTIVITY IN WIRELESS NETWORKS</dc:title>
  <dc:creator>Xu, Xiaohua</dc:creator>
  <dc:description>The limited energy resources, instability, and lacking central control in wireless networks motivates the study of connected dominating set (CDS) which serves as rout- ing backbone to support service discovery, and area monitoring and also broadcasting. The construction of CDS involves both coverage and connectivity. We ¯rst study sev- eral problems related to coverage. Given are a set of nodes and targets in a plane, the problem Minimum Wireless Cover (MWC) seeks the fewest nodes to cover the targets. If all nodes are associated with some positive prices, the problem Cheapest Wireless Cover (CWC) seeks a cheapest set of nodes to cover the targets. If all nodes have bounded lives, the problem Max-Life Wireless Cover (MLWC) seeks wireless coverage schedule of maximum life subject to the life constraints of individ- ual nodes. We present a polynomial time approximation scheme (PTAS) for MWC, and two randomized approximation algorithms for CWC and MLWC respectively. Given a node-weighted graph, the problem Minimum-Weighted Dominating Set (MWDS) is to ¯nd a minimum-weighted vertex subset such that, for any vertex, it is contained in this subset or it has a neighbor contained in this set. We will propose a (4+²)-approximation algorithm for MWDS in unit disk graphs. Meanwhile, for the connecting part, given a node-weighted connected graph and a subset of terminals, the problem Node-Weighted Steiner Tree (NWST) seeks a lightest tree connecting a given set of terminals in a node-weighted graph. We present three approximation algorithms for NWST restricted to UDGs. This dissertation also explores the applications of CDS, and develops e±cient algorithms for the applications such as real-time aggregation scheduling in wireless networks. Given a set of periodic aggregation queries, each query has its own period , and the subset of source nodes Si containing the data, we ¯rst propose a family of e±cient and e®ective real-time scheduling protocols that can answer every job of each query task within a relative delay under resource constraints by addressing the following tightly coupled tasks: routing, transmission plan constructions, node activity scheduling, and packet scheduling. Based on our protocol design, we further propose schedulability test schemes to e±ciently and e®ectively test whether, for a set of queries, each query job can be ¯nished within a ¯nite delay. We also conduct extensive simulations to validate the proposed protocol and evaluate its practical performance. The simulations corroborate our theoretical analysis.</dc:description>
  <dc:description>Ph.D. in Computer Science, May 2012</dc:description>
  <dc:contributor>Li, Xiang-Yang</dc:contributor>
  <dc:date>2012-04-25</dc:date>
  <dc:date>2012-05</dc:date>
  <dc:type>Dissertation</dc:type>
  <dc:format>application/pdf</dc:format>
  <dc:identifier>islandora:8954</dc:identifier>
  <dc:identifier>http://hdl.handle.net/10560/2861</dc:identifier>
  <dc:source>CS / Computer Science</dc:source>
  <dc:source>Illinois Institute of Technology</dc:source>
  <dc:language>en</dc:language>
  <dc:rights>In Copyright</dc:rights>
  <dc:rights>http://rightsstatements.org/page/InC/1.0/</dc:rights>
  <dc:rights>Restricted Access</dc:rights>
</oai_dc:dc>
