Download Location Tracking in a Wireless Sensor Network by Mobile Agents

Location Tracking in a WSN
by Mobile Agents and
Its Data Fusion Strategies
Yu-Chee Tseng, Sheng-Po Kuo, Hung-Wei Lee, and Chi-Fu
Huang
Young-sam Kim / M.D Course
School of Information Technology
Dept. of Computer Engineering
Korea University of Technology and Education
Contents
 Abstract
 Introduction
 Network Model & Problem Statement
 The Location Tracking Protocol
 Fusion & Delivery of Tracking Results
 Prototyping Experiences and Simulation Results
 Conclusion
 Q/A
- Abstract -
Abstract (1)
1. WSN (Wireless Sensor Network)
 Providing ubiquitous sensing, computing and communication
capability -> greatly facilitate human life
2. Location Tracking (1)
 One of the central issues in sensor networks.
 To monitor the roaming path of a moving object.
Abstract (2)
3. Location Tracking (2)
 Similar to the location-update problem in PCS networks.
 Location Tracking is more challenging in two senses.
1) Central control mechanism & backbone network. (X)
2) Wireless communication bandwidth is very limited.
4. Proposed paradigm
 Novel protocol based on the mobile agent paradigm.
 The communication & sensing overheads are greatly reduced.
 Based on IEEE 802.11b, NICs
- Introduction -
WSN (1)
Wireless communication
Rapid progress
Wireless Sensor Network
MEMS technologies
Inexpensive node
Environmental
Info
collecting
processing
storing
WSN (2)
1. Sensor are connected
 Past : wire lines.
 Today : wire lines + wireless ad hoc network
1) The flexibility of installation & configuration is greatly improved.
2) Research activities have recently been commenced in SN
WSN (3)
2. Issues remain to be resolved
 Scalability
- coverage and exposure problems
 Stability
- stable and fault-tolerant
 Power-saving
- since no plug-in power is available
- energy consumption of communications might be a major factor
- mobile agent-based solutions are sometimes more power-efficient
Proposed paradigm
3. Novel protocol based on the mobile agent paradigm
 To solve the location tracking problem
 Advantage
1) sensing, computing & communication overheads can be greatly
reduced. -> delivery & fusion of the tracking results
2) on-site or follow-me services may be provided
Network Model &
Problem Statement
Network Model (1)
 Sensor network (2D)
 Triangular network (regular)
Network Model (2) & Problem Statement
 Sensing scope is r
 Working Area is A0, Backup Area is A1, A2, A3
Practice errors may exist, and thus
more sensors will be needed to
improve the accuracy.
The Location Tracking Protocol
Basic Idea
 Proposed protocol is derived by the
cooperation of sensors. (master 1, slave 2)
Protocol Details (1)
 Assume that …
1) Sensors can distinguish one object from the other
2) Each object periodically send a unique ID
3) focus on only one particular object
Protocol Details (2)
 Master agent : closets to the object
- go to master state & protocol
 Slave agents : nearby sensors
- go to slave state & protocol
 Once the object enters the backup areas,
the roles of master & slave may be changed
Protocol Details (3)
For track3,
track1, the
track2,
onlymaster
the slave
discovers
agent inone
two
slaves
S1
slave
willas
losing
bewell
revoked,
the
as itself
target
and
losing
new the
one will
simultaneously.
be
target
invited.
Master
Protocol Details (4)
 Each sensor will keep an object list (OL).
unique identity, denote by ID, two sub-field
 Two sub-field : status & time-stamp
1) ID.state : Master, Slave, Standby, Inhibited
2) time-stamp is the time when the record is last
updated.
Protocol Details (5)
 Seven types of control messages
1) bid-master(ID, sig)
2) assign_slave(ID, si, t)
3) revoke_slave(si)
4) inhibit(ID)
5) release(ID)
6) move_master(ID, si, hist)
7) data(ID, sig, ts)
Basic Protocol
Election Protocol
Master Protocol
Slave Protocol
Extension to Irregular Network
Topologies
The election process does not need to be
changed.
The rules to migrate masters/slaves need to
be modified.
Sensors need to know the locations of at
least their two-hop neighbors.
Still use one master and two slaves to track
an object.
Extension to Irregular Network
Topologies
 How to define the master & slaves ?
The problem can be solved by a divide-and-conquer
solution in time complexity
Fusion & Delivery of
Tracking Results
Fusion & Delivery of Tracking Results
(1)
Assume that…
one of the sensors in the network serves as the
gateway connecting to a location server in the
wireline network.
Fusion & Delivery of Tracking Results
(2)
 Propose three data delivery solutions.
1) Non-Agent-Based (NAB) strategy.
Each sensor works independently and forwards its
sensing results back to the gateway
2) Threshold-Based (TB) strategy.
3) Distance-Based (DB) strategy.
The delivery action may be taken only when the
master agent moves.
Prototyping Experiences
Prototyping Experiences
IEEE 802.11b NICs
Sensor 0
Object
Sensor 1
Sensor 2
Prototyping Experiences
Prototyping Experiences
 Position approximation algorithm
Prototyping Experiences
Prototyping Experiences
Prototyping Experiences
Prototyping Experiences
Simulation Results
Simulation Results (1)
Simulation Results (2)
Conclusions
Conclusion
A mobile-agent approach, A data fusion
model and several data delivery strategies are
significantly reducing the communication &
sensing overheads.
Q/A
Thank you