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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
Design and Validation of Data Transmission policies for Low-Power WSNs| Slide 2
2. Related Works 3. Experimental Setup 1. Introduction 4. Results 5. Optimization 6. Conclusions
Introduction
Vital signs datax
x
x Positions & Movements
Types & Composition
2. Related Works 3. Experimental Setup 1. 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
2. Related Works 3. Experimental Setup 1. 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
2. Related Works 3. Experimental Setup 1. 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
2. Related Works 3. Experimental Setup 1. 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
2. Related Works 3. Experimental Setup 1. 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
2. Related Works 3. Experimental Setup 1. 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
2. Related Works 3. Experimental Setup 1. 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%
2. Related Works 3. Experimental Setup 1. 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
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. Conclusions 1. Experimental Setup II 5. Future Work
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
Questions?
Design and Validation of Data Transmission policies for Low-Power WSNs| Slide 13
Thank you for your attention
Mónica Vallejo Velásquez [email protected]
http://artecs.dacya.ucm.es/
