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Power Saving Operations in Target Tracking and Surveillance Sensor Networks

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Many, cheap sensors. wireless easy to install. intelligent ... How long will a target travel without exposure to any sensor? 13. QoSurv on Moving Targets ... – PowerPoint PPT presentation

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Title: Power Saving Operations in Target Tracking and Surveillance Sensor Networks


1
Power Saving Operations in Target Tracking and
Surveillance Sensor Networks
  • Chao Gui, Prasant Mohapatra
  • Networks Lab. UC. Davis
  • Seminar, Jan 2004

2
Agenda
  • Target tracking and surveillance sensor networks
  • Power-saving operations and the network
  • Sleep planning during surveillance
  • Performance Evaluation

3
Multiple Target Tracking (MTT) Problem
  • Problem Statement (Sittler-1964, Sastry-2004)
  • A varying number of targets
  • Arise at random in space and time
  • Move with continuous motions
  • Persist for a random length of time and disappear
  • Positions of targets are sampled at random
    intervals
  • Measurements are noisy and
  • Detection probability lt 1.0 (missing
    observations)
  • False alarms
  • Goal For each target, find its track!!!

4
Wireless sensor networks
  • Wireless sensor node
  • power supply
  • sensors
  • embedded processor
  • wireless link
  • Many, cheap sensors
  • wireless ? easy to install
  • intelligent ? collaboration
  • low-power ? long lifetime

5
Cooperative Tracking with SN
  • Advantages
  • Easy deployment
  • Track multiple targets simultaneously
  • Difficulties
  • Very limited resources
  • Work with local information

6
Frisbee A Networks Model for Target Tracking
Applications
7
Frisbee A Networks Model for Target Tracking
Applications
  • Interesting events happen infrequently, and
    only take place at certain locations.
  • Make the sensors sleep during the long interval
    of inactivity.
  • When and where event occurs, only a limited zone
    of network is kept in full active state.
  • For moving target, the active zone moves along.

8
Agenda
  • Target tracking and surveillance sensor networks
  • Power-saving operations and the network
  • Sleep planning during surveillance
  • Performance Evaluation

9
Work cycle
  • Two states for a sensor node
  • Surveillance state
  • no events of interest in the field, but ready
    to detect any possible occurrences
  • Tracking state
  • reacts in response to any moving target,
    sensors collaborate in tracking
  • Power-saving operations be considered in full
    work cycle.

10
Research Issues
  • Intuitive and basic scheme
  • Sleep, wakeup periodically
  • Check for messages and sensing for targets
  • If target detected, stop sleeping
  • Basic scheme adopted
  • Two issues should be considered
  • Quality of surveillance
  • In-time, in-place transition between two work
    stages

11
Problems for Sleeping
  • Sleeping reduces the detectability of the network
  • When a target first enters the SN field, and all
    the nodes are not in ready-tracking state, how
    long will it travel without exposure to any
    sensor?

12
Quality of Surveillance
  • QoSurv in general
  • Coverage, p-coverage
  • Minimum exposure path (MEP)
  • Aka. maximum breach path
  • QoSurv on moving targets
  • Special metrics needed
  • Coverage --not necessary for moving object
  • MEP --cannot yield direct guideline on sensor
    deployment
  • Proposed metric
  • How long will a target travel without exposure to
    any sensor?

13
QoSurv on Moving Targets
Assumptions (1) No sleeping (2) Non-uniform but
static sensing range (3) Uniform and random
deployment of sensors (4) Area X not fully
covered.
14
Approximation of ALUL(X)
  • Theorem For any straight line of length l in the
    field, the expected number of intersections the
    line with the disc boundaries is
  • Proposition For any straight line of length l,
    and let e be expected number of intersections
    within disc boundaries, l/e approximates ALUL(X).

15
Experiment Result
16
Agenda
  • Target tracking and surveillance sensor networks
  • Power-saving operations and the network
  • Sleep planning during surveillance
  • Performance Evaluation

17
Role of Sleep Planning
  • QoSurv study guides sensor deployment
  • Number of nodes
  • Distribution
  • Over-deployment of sensor nodes
  • Make spare nodes sleep
  • Active nodes follow deployment guideline

18
Sleep Planning Methods
  • Random Independent Sleeping (RIS)
  • Independent decide when to wake-up
  • Randomized schedule
  • Neighbor Collaborative Sleeping (NCS)
  • Collaborate on whose turn to be on duty
  • Planned Distribution Methods
  • Use location info., make the active nodes
    distribute in a planned manner

19
Random Independent Sleeping
  • Alertness level
  • Each node remain active for a percent of total
    time.
  • Timeslots
  • Within each timeslot, active for aTslot
  • Randomized timeslot boundaries

20
Neighbor Collaborative Sleeping
  • PEAS (Ye-2003)
  • Each node initially sleep for random time
  • When wakeup, do Probe Environment
  • If find working node, decide next sleep time,
    then go sleep
  • If not found, become working node till energy
    used up

21
Examples
2
Reply
4
1
2
1
Rp
3
3
(a) 2 and 3 are working, 1 probes and starts
(b) 4 probes and 2 replies 4 goes back to
sleep
2
1
6
1
3
3
(c) 2 fails or exhausts energy
(d) 6 probes and replaces 2
22
Revised PEAS
  • Why revise
  • Once starts working, a node does not sleep
  • Goal Nodes take turn for duty, balance energy
    consumption among all nodes
  • PECAS Probe Environment and Collaborated
    Adaptive Sleeping

23
PECAS by example
2
Reply (Ts)
4
1
2
1
Rp
3
3
2 and 3 are working, 1 probes and starts
4 probes and 2 replies with Ts 4 goes back to
sleep for Tse
2
1
4
1
3
3
Ts time later, 2 goes to sleep
4 probes and replaces 2
24
Planned Distribution Methods 2-D Mesh
  • Only nodes at planned locations are active
  • Use 2-D mesh for spatial pattern
  • Parameters
  • r Sensing range,
  • lGGrid spacing

r
lU
lG
25
2-D Mesh
  • For i-th horizontal line, nodes with x-coordinate
    in range ilG-s, ilGs are active
  • Similar for j-th vertical line
  • Each line forms a covered stripe of width 2r2 s
  • Each uncovered area is approximately a square of
    side length lU
  • lUlG-2r-2 s

r
lU
lG
26
Deterministic ALUL(X)
  • Theorem Let X be the monitored area of size LL.
    The physical deployment of sensors is uniformly
    random distribution of adequate density. The
    distribution of active sensors follows the 2-D
    mesh planned pattern. Then, ALUL(X) is

27
Agenda
  • Target tracking and surveillance sensor networks
  • Power-saving operations and the network
  • Sleep planning during surveillance
  • Performance Evaluation

28
Performance Evaluation
29
Performance Evaluation
30
Performance Evaluation QoSv
31
Performance Evaluation QoSv
32
QoSv of mesh with errors
33
Performance Evaluation
  • Performance Metric
  • total energy consumed
  • delay of detection
  • Simulation Setup
  • 800 nodes,
  • transmission range 55.9 m,
  • sensing range 20m
  • target speed 10 m/s

34
Performance Evaluation Relative Energy Save
35
Performance Evaluation Path Exposure
  • Definition Path Exposure
  • Summation of networks sensing intensity at each
    point along a path.
  • Sensing intensity of a sensor x at a point p is
    defined as S(x,p) 1/ x, p4.

36
Performance Evaluation Path Exposure
37
Questions, remarks?
38
References
  • S. Tilak, N.B. Abu-Ghazaleh, W. Heinzelman, A
    Taxonomy of Wireless Micro-Sensor Network
    Models, Mobile Computing and Communications
    Review, Vol. 6, No. 2.
  • A. Cerpa, J. Elson, M. Hamilton, J. Zhao,
    Habitat Monitoring Application Driver for
    Wireless Communications Technology, First ACM
    Sigcomm Workshop on Data Communications in Latin
    America and the Caribbean, Apr. 2001
  • K. Mechitov, S. Sundresh, Y. Kwon, G. Agha,
    Cooperative Tracking with Binary-Detection
    Sensor Networks, Technical Report
    UIUCDCS-R-2003-2379, Computer Science, UIUC,
    Sept. 2003
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