Opportunistic clock synchronization for ad hoc networks

Carrasco, Maria B.

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https://hdl.handle.net/2142/26050 Copy

Description

Title

Opportunistic clock synchronization for ad hoc networks

Author(s)

Carrasco, Maria B.

Issue Date

2011-08-25T22:10:51Z

Director of Research (if dissertation) or Advisor (if thesis)

Mitra, Sayan

Department of Study

Electrical & Computer Eng

Discipline

Electrical & Computer Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Date of Ingest

2011-08-25T22:10:51Z

Keyword(s)

• clock synchronization
• Ad hoc
• opportunistic
• broadcasts
• window of opportunity
• randomized

Abstract

An ad hoc network is a collection of computing nodes communicating over wireless channels without relying on any fi xed infrastructure such as servers and towers. Such networks are useful in rescue operations, and in rural and military settings. Clock synchronization is an essential building block for many ad hoc wireless network applications. It provides the participating computing nodes with logical clocks whose di erences can be bounded. Several traditional distributed clock synchronization algorithms use strict communication structures such as spanning trees. In such protocols, a node corrects its logical clock when it receives a new time-stamped message from its parent. In this thesis, we present a new clock synchronization protocol that exploits the broadcast medium in wireless networks, allowing nodes to opportunistically correct their logical clocks in order to converge to a reference time provided by a designated root node. Our protocol does not rely on a communication structure and is lightweight due to its low overhead. We also propose a variation of our opportunistic protocol, which further reduces overhead through randomized broadcast techniques. Our simulation-based experimental evaluation of the protocols illustrates that our opportunistic algorithms improve the accuracy of the nodes' logical clocks, when compared to a tree-based protocol. However, we show that the level of improvement is a function of the density of the wireless network. Additionally, the results show that our algorithms can produce around half the overhead, compared to an existing protocol that achieves higher levels of precision.

Graduation Semester

2011-08

Permalink

http://hdl.handle.net/2142/26050

Copyright and License Information

Copyright 2011 Maria B. Carrasco

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