1. Combined Human, Antenna Orientation in Elevation Direction and Ground Effect on RSSI in Wireless Sensor Networks
Syed Hassan Ahmed, Safdar H. Bouk, Nadeem Javaid, and Iwao Sasase
FIT’12, Comsats Institute of Information & Technology.
This work was partly supported by *Dr. Iwao Sasase, Dr Safdar Hussain Bouk & Dr Nadeem Javaid.
*Keio University 21st Century Center of Excellence Program on “Optical and Electronic Device Technology for Access Network” and Fujitsu Laboratories, Japan.
** Electrical Engineering Department, COMSATS Islamabad, Pakistan.

2. Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.
Agenda
Wireless Sensor Networks
Crossbow MicaZ Motes
Sensor less Sensor Network
Why SL-WSN?
Previous Approaches
Our Proposed Experimental Setup
Experimental Results
Conclusion and Future Work
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

3. Wireless Sensor Networks
A network that consists of sensor nodes (called “motes”) and base station(s) (gateway/sink node(s)).
Sensing module is either attached with the sensor node built-in in the sensor node that senses the environment.
Motes sense environmental parameters (e.g. light, temperature, motion, humidity, noise etc.) and forward readings to the sink node.
Sink node aggregates readings.
Fig : 01 WSN
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

4. Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.
Crossbow MicaZ Motes
IEEE compliant RF transceiver
2.4 to 2.48 GHz, a globally compatible ISM band
Direct sequence spread spectrum radio which is resistant to RF interference and provides inherent
250 kbps data rate
Supported by Mote Works™ wireless
sensor network platform for reliable,
ad-hoc mesh networking
Plug and play with Crossbow’s sensor boards.
Fig 02 : Sensor Architecture
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

5. Sensor less Sensor Network?
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

6. Sensor less Sensor Network
Sensor node with sensing module.
MDA 100 sensing board with temperature sensor. (It has expansion slots available to connect custom sensors)
It is known as appropriate sensor node.
Sensor node without sensing module.(SL-WSN)
Communication through RF chip.
RSSI values to be noticed during Experiment.
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

7. Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.
What is RSSI ??
In an IEEE system RSSI is the relative received signal strength in a wireless environment. RSSI is an indication of the power level being received by the antenna. Therefore, the higher the RSSI number (or less negative in some devices), the stronger the signal.
RSSI values will be focused in coming real time
scenarios.
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

8. Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.
Why SL-WSN?
Objective and Motivation:
Object Detection
Tracking & Locating
Cost effectiveness
Low Power Consumption
No Power needed for:
Pre-ADC data processing
Post-ADC data processing
New Research Area
New and efficient methods are needed to effectively detect, locate and track objects.
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

9. Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.
Previous Approaches
Previous research has shown that RSSI is not a good measure of distance, however they fail to analyze the effect of Antenna orientation on RSSI.
In past research, Sensor nodes were deployed at above the ground level. However, the RSSI Values are very strong above the ground level compared to the sensors deployed at the ground level.
Antenna orientation is not the main focus in past research.
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

10. Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.
Proposed Experiment
Measurement of RSSI ( Receive Signal Strength Indicator)
Sensing different objects by monitoring RSSI.
Antenna Orientation
Distance between base station and sensor
Human Mobility
Effect of passing human body with varying Speed
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

11. MicaZ Mote Configuration
 =0°
 =45°
 =90° Y X
Azimuth
AUT’s Z-axis during experimental analysis.
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

12. Effect of Human Mobility on RSSI: Experimental Setup
Antenna Orientation
Node(s) Placed on the ground
Fig : 03 Slow Pace with different Antenna Orientation Angles
Distance
Fig 04: 0° Antenna Orientation with varying Movement Paces

13. Experimental Results Fig. 05 Single Person Slow Pace
45° 0° 0°
45°
Fig. 05 Single Person Slow Pace
Fig. 06 Two Persons Slow Pace
Fig. 07 Single Person Medium Pace
Syed Hassan Ahmed
Fig. 08 Two Persons Medium Pace

14. Experimental Results (Continue……)0°
45° 0°
45°
Fig. 09 Single Person Fast Pace
Fig. 10 Two Persons Fast Pace
Fig. 11 Single Person Standard Deviation
Syed Hassan Ahmed
Fig. 12 Two Persons Standard Deviation

15. Conclusion and Future Work
We observed that:
Antenna orientation with ground effect has great impact on RSSI.
RF antenna propagation of MICAz mote is an important factor in planning the sensor network deployment and optimized WSNs area coverage solutions.
Future Work:
Object movement / Event detection using statistical approach(es) [e.g. Time Series Analysis]:
Moving Averages
Changes in Averages
Variations in continuous variance etc.
Adaptive & Efficient Computation and reduction of False Alarms.
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

16. Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.
Thanks Q & A
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

17. Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.
Sensing Board
It includes the actual sensors which collects the readings from physical environment and passes to sensor node attached to it.
- Light, Temperature - Microphone, Sounder - Tone Detection Circuit - Compatible with MICA, MICA2 and MICAz
- Precision thermistor, light sensor/photocell - Prototyping area supports connection to all 51 pins on expansion connector unconnected solder points for breadboarding.
MTS300
MDA 100
MDA 100 with MICAz node
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

18. MIB ( Mote Interface Board)
It is used for programming the sensor nodes and also work as a gateway or based station(sink node).
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

19. Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.
Outcomes……….
We found that antenna orientation has drastic effect on RSSI.
Fast moving objects can also have effect on RSSI.
The results show that antenna orientation must be considered seriously when sensor network is deployed in the real world scenario.
Object / Activity detection has different effect on different antenna orientation.
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

20. Effect of Car on RSSI: Conclusion
we experimentally analyzed the effect of fast moving vehicle on the RSSI in presence of the ground effect and antenna orientation in elevation direction.
It has been observed that the slow speed causes high deviation in RSSI compared to the faster speed.
Some irregularities in the RSSI fluctuations are also observed when antenna is elevated at 45 and 90.
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

21. Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.
RF Chip (cc2420)
True single-chip 2.4 GHz
IEEE compliant RF transceiver
designed for low power and low voltage
wireless applications.
CC2420 includes a digital direct sequence spread spectrum.
Baseband modem providing a spreading
gain of 9dB and an effective data rate of
250 kbps.
Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.