Fine-Grained Dynamic Localization in Ad-Hoc Networks of Sensors
Andreas Savvides, Chih-Chieh Han and Mani B. Strivastava Networked and Embedded Systems Lab Department of Electrical Engineering University of Calfornia, Los Angeles
ABSTRACT
Keywords
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1. INTRODUCTION 1.1 Sensor Networks and Location Discovery
166
1.2 Our Work
1.3 Paper Organization
2. BACKGROUND AND RELATED WORK 2.1 Background
167
C a B b A c
Sines Rule
(a)
Cosines Rule
(b)
(c)
2.2 Related Work
168
2.6 x 10
4
Measured P=7 LS fit P=7 Measured P=13 LS fit P=13
3.
RESEARCH METHODOLOGY
2.4
2.2 Received Signal Strength
2
3.1 Ranging Characterization
3.1.1 Received Signal Strength
1.8
1.6
1.4
1.2
0
5
10 Distance(m)
15
20
25
169
3.1.2 ToA using RF and Ultrasound
Transmitter
Radio Signal T1 Ultrasound Pulse T2 Distance = (T2-T1) x S Distance
Receiver
3.2 Signal Strength vs. ToA ranging
140
120
MCU time measurement
100
80
60
40
20
0
50
100
150 Distance (cm)
200
250
300
4. LOCALIZATION ALGORITHMS
170
4.1 Atomic Multilateration
11 00 11 00 1111 1111 0000 0000 11 00 11 00 1111 1111 0000 0000 1111 1111 0000 0000 1111 1111 0000 0000 1111 1111 0000 0000 1111 1111 0000 0000 11 1111 1111 00 0000 0000 00 111111 000000 11 111111 000000 11 00 11 00 11 00 11 00
(a)
11 00 1 111 000 11 00 111 000 111 000 111 000 111 000 111 000 111 000 111 0002 111 000 111 000 11 00 11 00 11 00 11 00 11 00 11 00 11 00 11 00 11 00 3 11 00 11 00
(b)
5 11 00 11 00 11 00 11 00 11 00 11 00 11 00 11 00 11 4 00 11 00 11 00 1111 0000 1111 0000 1111 0000 1111 0000 1111 0000 6 11 00 1111 0000 11 00
11 00 11 00
Unknown Location Beacon Node
X'
11 00 11 00
11 00 11 00
X
11 00 11 00
(c)
171
Ranging Error 0.18 0.16 Error Distance (m) 0.14 0.12 0.1 0.08 0.06 0.04 0.02 0
12 20 21 24 26 28 34 36 13 40 42 44 47 49 16 18 31 38
Ranging + Beacon Error
Node Id
4.2 Iterative Multilateration
4.3 Collaborative Multilateration
172
4.4 Further Optimizations
173
5.
NODE AND BEACON PLACEMENT
174
1 P(n=0) P(n=1) P(n=2) P(n>=3)
0.9
0.8
0.7
0.6 P(n)
0.5
0.4
0.3
0.2
0.1
0
0
50
100
150
200
250 Nodes
300
350
400
450
500
6.2 Location Information Dissemination and Routing
100
percentage of resolved nodes
80
60
40
20
0 300 250 200 150 100 50 total nodes 0 0 20 percent of initial beacons 40 60 80 100
6.
IMPLEMENTATION AND EXPERIMENTATION 6.1 Medusa Node Architecture
175
6.3 Experimental Setup
18 2.4kbps OOK 2.4kbps ASK 19.2kbps OOK 19.2kbps ASK RX mode
17
16
Consumed power(mW)
15
14
13
12
11
10
9
1
2
3
4
5
6
Power Level
I sensor = Vtest Rtest
DR 3000 Sensor
HP 1660 Power Supply
6.4 Power Characterization
VSensor = Vsup ply - Vtest Power = I sensor Vsensor
C1 C2
ADC
VSensor
Rtest Vtest
Energy = Power time
AS90LS8535
ISensor
...