RF Propagation Analysis of MICAz Mote’s Antenna with

Ground Effect

Syed Hassan Ahmed, Safdar H. Bouk, Nadeem Javaid, and Iwao Sasase

IMNIC’12, RIU Islamabad.

2

AgendaWireless Sensor Networks

Crossbow MicaZ MotesSensor less Sensor NetworkWhy SL-WSN?Previous ApproachesOur Proposed Experimental SetupExperimental ResultsConclusion and Future Work

Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

3

Wireless Sensor NetworksA 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

Crossbow MicaZ MotesIEEE 802.15.4 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 rateSupported by Mote Works™ wirelesssensor network platform for reliable, ad-hoc mesh networkingPlug 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

What is RSSI ?? In an IEEE 802.11 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

Objective and Motivation:Object DetectionTracking & Locating Cost effectivenessLow Power Consumption

No Power needed for: Pre-ADC data processing Post-ADC data processing

New Research AreaNew and efficient methods are needed to effectively detect,

locate and track objects.Syed Hassan Ahmed. MS Computer Engineering,

EE Dept, CIIT Islamabad.

Why SL-WSN?

9

Previous ApproachesPrevious 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

Proposed ExperimentMeasurement of RSSI ( Receive Signal

Strength Indicator)Sensing different objects by monitoring

RSSI.Antenna OrientationDistance between base station and sensor

MicaZ RSSI Evaluation in Lab Environment.

Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad. 11

MicaZ Mote Configuration =0°

=45°

=90°

Z

AzimuthX

Y

AUT’s Z-axis during experimental analysis.

Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad. 12

XY

Z

=0°

=0°

XY

Z

=0°

=0°

=45°

=90°

3m 5m 7m

XY

Z

=0°

=0° XY

Z

=0°

=0°

=45°

=90°

3m 5m 7m

(a) Both MICAz motes with AUT and MA are placed on the ground.

(b) MICAz mote with MA is placed on the ground and AUT MICAz mote is placed on the stool.

AUT

MA

AUT

MA

Exp

eri

men

tal

Sce

nari

o Ι

an

d ΙΙ

Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad. 13

Radiation Patterns during Transmission of Mica Z

RF radiation pattern of MICAz with AUT in Scenario-I at 3m apart RF radiation pattern of MICAz with AUT in Scenario-II at 3m apart

Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad. 14

RF radiation pattern of MICAz with AUT in Scenario-I at 5m apart RF radiation pattern of MICAz with AUT in Scenario-II at 5m apart

Radiation Patterns during Transmission of Mica Z

Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad. 15

RF radiation pattern of MICAz with AUT in Scenario-I at 7m apart RF radiation pattern of MICAz with AUT in Scenario-II at 7m apart

Radiation Patterns during Transmission of Mica Z

16

17

0° 45° 90° 135° 180° 225° 270° 315°

-95

-90

-85

-80

-75

-70

0° 45° 90° 135° 180° 225° 270° 315°

-70

-65

-60

-55

-50

-45

-400° 45° 90° 135° 180° 225° 270° 315°

-90-85-80-75-70-65-60-55-50

0° 45° 90° 135° 180° 225° 270° 315°

-90-85-80-75-70-65-60-55-50

0° 45° 90° 135° 180° 225° 270° 315°

-90

-85

-80

-75

-70

-65

-60

0° 45° 90° 135° 180° 225° 270° 315°4

5

6

7

8

9

102m3m5m8m

Antenna Orientation in Elevation Direction

RSS

I- S

tand

ard

Dev

iati

on

• Major effect at in RSSI and it’s standard deviation 90° and 270°.

Effect of Distance and Antenna Orientation on RSSI: Without any Movement

Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

18

Conclusion and Future WorkWe 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.

Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad. 19

ThanksQ & A

Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

20

Sensing Board It includes the actual sensors which collects

the readings from physical environment and passes to sensor node attached to it.

MTS300 MDA 100 MDA 100 with MICAz node

- 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 - 42 unconnected solder points for breadboarding.

Syed Hassan Ahmed. MS Computer Engineering, EE Dept, CIIT Islamabad.

21

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.

22

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.

23

Effect of Car on RSSI: Conclusionwe 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.

24

RF Chip (cc2420)True single-chip 2.4 GHzIEEE 802.15.4 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.