Presenter Ho-lin Chang
Dec 30, 2015
Presenter Ho-lin Chang
• Introduction• Design• Implementation• Evaluation• Conclusion and future Work
2
• Indoor location-based service
3
Healthcare Security Warehouse
• Existed indoor localization technique– UWB– Ultrasound– WiFi
4
UWB
WiFi
Ultrasound
• UWB (Ubisense)– Accuracy: 10 ~ 20 cm– Time difference of arrival– Expensive specialized
hardware (10,000 USD)
5
• Ultrasonic (Cricket)– Accuracy: 10 ~ 20 cm– Short range– Non-line of sight problem
6
• WiFi (Ekahau, RADAR)– RSS fingerprinting– Accuracy: 3 ~ 5m– Low cost– Offline training
7
Technologies Accuracy Properties
UWB 15 cm • Specialized hardware
Ultrasound 15 cm• Short range• Non-line of sight problem
WiFi 300~500 cm • Offline training
? cm range• Low cost• Radio• No offline training
8
• Develop a novel localization system – Spinning beacon (RF)– Indoor environment– Sub-meter accuracy• 50% < 39 cm• 90% < 70 cm
– Low cost• Low cost motes (100 USD)• Rotation motor
9
10
S
S
S
XX
RR
XX
11
The location of XThe location of X
X
S v
f vproject
12
X
Δf = 0 HzΔf = 0 HzΔf = 30 HzΔf = -30 Hz
timeΔf (t) = ?30Hz
0Hz
0Hz
-30Hz
vS
13
v(t)
S
X
α
x
y
dr
S : (r cosθ, r sinθ)v(t) = (-ωr sinθ, ωr
cosθ)
θ(t) = ωt+φ
X : (d cosα, d sinα)
14
S
v(t) X
αx
y
RRβ
15
16
S
S
S
XX
RR
XX
17
The location of X
18
500 Hz
A 900 MHz
900 MHz + 500 HzBThe location of X
19
The location of X
• Hardware–Crossbow MICA2
–Rotational motor
• Software– TinyOS 1.x–C/C++
20
• Testbed– 國發所地下室停車場– Three spinning beacons– 30 sample points (2m grid)
• 10 position samples (300 samples)• 3 angles (900 angles)
• Evaluation metrics– Positional error– Angular error
• Parameter Tuning
21
50% < 3 degrees
90% < 10 degrees
50% < 3 degrees
90% < 10 degrees
22
50% < 3 degrees
90% < 10 degrees
50% < 39 cm
90% < 70 cm
23
• Data collection time• Rotational velocity
• Interference frequency
• Angulation filtering threshold– Minimum distance as a quality indicator
24
25
26
Lower frequency estimation precision
27
28
• Track fast moving targets• Rotational device
29
• Develop a novel localization system– Spinning beacon– Indoor environment– Low cost– Sub-meter accuracy• 39cm / 70cm
30
• Reduce the localization latency–Reduce the routing time• Distributed version• Data compression
• Track the fast moving targets
31
34
r/d
0.10.30.5
0
35
36
37
k
A
B
Xv
fA
fB
|fA-fB||fA + ΔfX - fB|
R
S A
S
S
39
40
Time
Signal strength
• Each infrastructure perceives different Doppler shift.
• Localize the target by different Doppler shifts
Xv
41
I
I
I
II
I
Maximum Doppler shiftf : 900 MHz ω : 2.5 round/secr : 30 cm ~ 50 cm
42
0.3 ~ 1.5 sec 8 ~ 10 sec1st Doppler angulation
2nd Doppler angulation3rd Doppler angulation
Localization
43
v(t)
S
X
α
x
y
dr
S : (r cosθ, r sinθ, 0)v(t) = (-ωr sinθ, ωr cosθ, 0)
θ(t) = ωt+φ
X : (d cosα, d sinα, h)
44