Mobi-Sync: Efficient Time Synchronization for Mobile Underwater Sensor Networks

ABSTRACT:

Time synchronization is an important requirement for many services provided by distributed networks. A lot of timesynchronization protocols have been proposed for terrestrial Wireless Sensor Networks (WSNs). However, none of them can be directlyapplied to Underwater Sensor Networks (UWSNs). A synchronization algorithm for UWSNs must consider additional factors such as longpropagation delays from the use of acoustic communication and sensor node mobility. These unique challenges make the accuracy ofsynchronization procedures for UWSNs even more critical. Time synchronization solutions specifically designed for UWSNs are neededto satisfy these new requirements. This paper proposes Mobi-Sync, a novel time synchronization scheme for mobile underwater sensornetworks. Mobi-Sync distinguishes itself from previous approaches for terrestrial WSN by considering spatial correlation among themobility patterns of neighboring UWSNs nodes. This enables Mobi-Sync to accurately estimate the long dynamic propagation delays.Simulation results show that Mobi-Sync outperforms existing schemes in both accuracy and energy efficiency.

EXISTING SYSTEM:

This paper addresses the time synchronization problem, acritical service in any sensor network. Nearly all UWSNapplications depend on time synchronization service. Forexample, data mining requires global time information,TDMA, one of the most commonly used Medium AccessControl (MAC) protocols, often requires nodes to besynchronized. Furthermore, most of the localization algorithms for underwater and terrestrial sensor networks assume the availability oftime synchronization service.Numerous times synchronization protocols for terrestrialWireless Sensor Networks (WSNs) have been proposed inthe literature synchronization accuracy and energy efficiency for land-basedapplications is cogent. However, most of these approachesassume that the propagation delay among sensors isnegligible. This is not the case in UWSNs, which sufferfrom the low propagation speeds of acoustic signals(roughly 1,500 m/s in water). Sensor node mobility alsocontributes to long and variable propagation delay inUWSNs. These additional complicating factors renderprevious approaches less suitable for adaptation to UWSNs.Furthermore, the batteries of underwater sensor nodes aredifficult to recharge and it is often impractical to replace dueto their relative inaccessibility. This lack of serviceabilityimposes even more stringent requirements. The UWSN willneed to be energy efficient. This set of distinguishingcharacteristics introduces new challenges into the design oftime synchronization schemes for UWSNs.

DISADVANTAGES OF EXISTING SYSTEM:

  • Low communication bandwidth, long propagation delays, higher error probability, and sensor node mobility.
  • The batteries of underwater sensor nodes are difficult to recharge and it is often impractical to replace due to their relative inaccessibility. This lack of serviceability imposes even more stringent requirements.
  • The UWSN will need to be energy efficient. This set of distinguishing characteristics introduce new challenges into the design of time synchronization schemes for UWSNs

PROPOSED SYSTEM:

This paper proposesMobi-Sync, a high energy efficient time synchronizationscheme specifically designed for mobile UWSNs.The distinguishing attribute of Mobi-Sync is how itutilizes information about the spatial correlation of mobilesensor nodes to estimate the long dynamic propagationdelays among nodes. The time synchronization procedureconsists of three phases: delay estimation, linear regression,and calibration. Phase I acquires information about thespatial correlations of the mobile sensor nodes to accuratelyestimate the propagation delays. In Phase II, sensor nodesperform linear regression based on MAC layer time stampsand corresponding propagation delays to produce initialestimates of the clock skews and offsets. These initial resultsserve as inputs to Phase III, which calibrates the estimates,further improving the synchronization accuracy. Duringcalibration, the final clock skew and offset estimates areobtained by updating certain parameters and repeating thedelay calculations and linear regressions. Extensive simulations demonstrate the effectiveness of the proposedapproach for time synchronization, confirming that it doesnot suffer from mobility. The results indicate that MobiSync outperforms existing schemes with respect to bothaccuracy and energy efficiency

ADVANTAGES OF PROPOSED SYSTEM:

Extensive simulations demonstrate the effectiveness of the proposedapproach for time synchronization, confirming that it doesnot suffer from mobility. The results indicate that MobiSync outperforms existing schemes with respect to bothaccuracy and energy efficiency.

SYSTEM CONFIGURATION:-

HARDWARE REQUIREMENTS:-

Processor-Pentium –III

Speed- 1.1 Ghz

RAM- 256 MB(min)

Hard Disk- 20 GB

Floppy Drive- 1.44 MB

Key Board- Standard Windows Keyboard

Mouse- Two or Three Button Mouse

Monitor- SVGA

SOFTWARE REQUIREMENTS:-

Operating System: WINDOWS XP

Front End: C#.NET

TOOL: VISUAL STUDIO 2008

Database: SQL SERVER 2005

REFERENCE:

Jun Liu,Student Member, IEEE Computer Society, Zhong Zhou, Member, IEEE Computer Society, Zheng Peng,Member, IEEE Computer Society, Jun-Hong Cui, Member, IEEE Computer Society, Michael Zuba,Student Member, IEEE Computer Society, and Lance Fiondella,Member, IEEE Computer Society “Mobi-Sync: Efficient Time Synchronization for Mobile Underwater Sensor Networks” IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS, VOL. 24, NO. 2, FEBRUARY 2013.