1. Design and Validation of Data Transmission
policies for Low-Power WSNs
Group of Architecture and Technology of Computing Systems
Madrid, March 11 / 2013
Monica A. Vallejo, Joaquin Recas , Jose L. Ayala
Complutense University of Madrid, Spain

2. Design and Validation of Data Transmission policies for Low-Power WSNs| Slide 2
2. Related Works 3. Experimental Setup1. Introduction 4. Results 5. Optimization 6. Conclusions
Introduction
Vital signs datax
x
xPositions & Movements
Types & Composition

3. 2. Related Works 3. Experimental Setup1. Introduction 4. Results 5. Optimization 6. Conclusions
Introduction
1. Characterize the mechanisms that interfere on the links quality of the WBSNs
a) Analyze the effects of the dielectric properties of biological tissues
b) Analyze the effect of simple and complex body movements
c) Analyze the effect of different body types
2. Establish a set of predictive and reactive policies for energy optimization
guaranteeing it the transmission quality.
 Reactive policy approach: reduces the effects of body movement and body
type on link quality, by setting the transmitted power in reactive form.
This work addresses the following goals:
Design and Validation of Data Transmission policies for Low-Power WSNs| Slide 3

4. 2. Related Works 3. Experimental Setup1. Introduction 4. Results 5. Optimization 6. Conclusions
Dielectric properties of biological tissues
Design and Validation of Data Transmission policies for Low-Power WSNs| Slide 4
Place(a/b)
Scenarios
d variable
Skin
Fat
Muscle
Bone
25cms
Place
a) Anechoic chamber
b) Outdoor environment
Scenarios
a) LOS
b) NLOS by tissues
Tissues types
Skin, fat, muscle, bone
Tissues Organization
a) homogeneous
b) layered tissues /homo
c) layered tissues/ hetero

5. 2. Related Works 3. Experimental Setup1. Introduction 4. Results 5. Optimization 6. Conclusions
Measurement Results : biological tissues
Design and Validation of Data Transmission policies for Low-Power WSNs| Slide 5
heterogeneous
homogeneous
Lower water
content
Higher water
content
worst case
• Attenuation among 20dBm
to 30dBm for the NLOS in
relation to free space.
• Dielectric properties and
the presence of the
different interfaces
determine the reflected
and transmitted energy of
EM wave.
Observations

6. 2. Related Works 3. Experimental Setup1. Introduction 4. Results 5. Optimization 6. Conclusions
Measurement Results : biological tissues
Design and Validation of Data Transmission policies for Low-Power WSNs| Slide 6
• Layered tissue causes that the RSSI
decreases significantly compared
with homogeneous tissue.
• Signal strength can drop up 20 dBm.
• Fat tissue used are much thinner
than the corresponding penetration
depths (113 mm at 2.45GHz)
• The influence of a medium’s
thickness decreases as the medium
becomes thicker (fat3 vs fat 2)
worst
case
Observations

7. 2. Related Works 3. Experimental Setup1. Introduction 4. Results 5. Optimization 6. Conclusions
Measurement Results : biological tissues
Design and Validation of Data Transmission policies for Low-Power WSNs| Slide 7
worst case
threshold (-94dBm)
critical case
Packet loss

8. 2. Related Works 3. Experimental Setup1. Introduction 4. Results 5. Optimization 6. Conclusions
Body types, positions and movements
The coordinator is programmed to provide RSSI
reading, CRC bit reading, and the sequence
number for each data packet received. Then, from
the second beacon, the coordinator integrates and
sends this information on payload.
External node passively listens the
beacon packets and takes periodic
noise floor measurements
10sec
A Java application draws in real time the
RSSI of each packet and the noise floor
measured during the test
USB
interface
Design and Validation of Data Transmission policies for Low-Power WSNs| Slide 8
Configuration

9. 2. Related Works 3. Experimental Setup1. Introduction 4. Results 5. Optimization 6. Conclusions
Results: Types & Positions & Movements
Design and Validation of Data Transmission policies for Low-Power WSNs| Slide 9
 Subject 1 and Subject 2 (both
taller than the average)
exhibit greater percentage of
packet losses versus Subjects
3 and 4.
 In L1/P4 the signal has to go
through a big body section
and suffers more attenuation
for S1 (overweight) than S2
(average).
Observations
50%<PER<10%

10. 2. Related Works 3. Experimental Setup1. Introduction 4. Results 5. Optimization 6. Conclusions
PER=0%
threshold (-94dBm)
PER>50%
15%<PER<50%
measured
threshold
Lossy positions
Lossless positions
LOS & short distance
Design and Validation of Data Transmission policies for Low-Power WSNs| Slide 10
Results: Types & Positions & Movements

11. Optimization for Shimmer node
Design and Validation of Data Transmission policies for Low-Power WSNs| Slide 11
At optimum power for
every phase the total
energy is 29.9 J
At maximum power the
transmission is lossless
but consumes 46.27 J
At minimum power, total
energy is 48.75 J. Almost
95% are retransmissions
2. Results II 3. Optimization 4. Conclusions1. Experimental Setup II 5. Future Work

12.  Mónica Vallejo, Joaquín Recas, José L. Ayala: Channel Analysis and
Dynamic Adaptation for Energy-Efficient WBSNs. UCAmI 2012: 42-49
Publications
Design and Validation of Data Transmission policies for Low-Power WSNs| Slide 12

13. Questions?
Design and Validation of Data Transmission policies for Low-Power WSNs| Slide 13
Thank you for your
attention
Mónica Vallejo Velásquez
mavallejov@unal.edu.co
http://artecs.dacya.ucm.es/