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PERFORMANCE MEASUREMENTS OF WIRELESS SENSOR NETWORKS

PERFORMANCE MEASUREMENTS OF WIRELESS SENSOR NETWORKS. Gizem ERDOĞAN. WIRELESS SENSOR NETWORKS. Wireless Battery powered Ad-hoc Sense & monitor : temperature, humidity, light intensity, voltage, current, volume, acceleration, sound, pressure ,etc.

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PERFORMANCE MEASUREMENTS OF WIRELESS SENSOR NETWORKS

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  1. PERFORMANCE MEASUREMENTS OF WIRELESS SENSOR NETWORKS Gizem ERDOĞAN

  2. WIRELESS SENSOR NETWORKS • Wireless • Battery powered • Ad-hoc • Sense & monitor : temperature, humidity, light intensity, voltage, current, volume, acceleration, sound, pressure ,etc. • Various application fields: military, health care, traffic control, scientific monitoring • Important aspects: Energy efficiency, self configuration

  3. Studies of anastasi et al. • Berkeley family motes • (a) mica2 • (b) mica2dot • 4-Mhz, 8-bit Atmel microprocessor • 512 KB of non-volatile flash memory • 32-KHz clock • RFM ChipCon Radio bit rate of 19.2 Kbps • CSMA/CA • TinyOS

  4. Experimental environment • Different traffic conditions • Outdoor environment • Temperature • Humidity • Fog • Rain • 10 replicas in different times • Average values as well as upper &lower bounds • Virtual ground • Limits reflection and bad electromagnetic wave’s perturbation

  5. Parameters values

  6. definitions • Transmission Range (TX_range): the range within which a transmitted frame can be successfully received • the transmission power • the radio propagation properties • Carrier Sensing Range (CS_range) :the range within which the other sensor nodes can detect a transmission • sensitivity of the receiver • the radio propagation properties

  7. EXPERIMENTAL RESULTSavailable bandwidth • Maximum size message 56 bytes • 18-byte preamble • 2-byte synchronization + • 36 bytes data • Theoretical throughput

  8. EXPERIMENTAL RESULTSavailable bandwidth cont. • m : the amount of data to be transmitted. • For maximum size frame 36 bytes • Tframe : time required to transmit a MAC data frame at 19.2 Kbps. • 56*8 /19.2 * 10-3= 23.33 ms; • (Bmin + IBmax)/2 : the average backoff time • ( 15 +68.3)/2=41.65 ms • Expected throughput :4.43 Kbps • Estimated throughput: 4.4 Kbps

  9. EXPERIMENTAL RESULTSpower consumption

  10. EXPERIMENTAL RESULTSpower consumption cont.

  11. EXPERIMENTAL RESULTSpower consumption cont. • Real World Application • Mica2 motes • Sample the light in every 1 second • Transmit 8 byte message to another node • When no messages to be sent, the radio turns off and the motes power down. • Leaked current while sampling is 20mA • Leaked current while transmitting 18mA. • Leaked current when powered down 10uA. • Average current leaked in a cycle 0.19 mA, • Average power consumption 0.19*3=0.57mW • Lifetime of the network: more than a year!

  12. EXPERIMENTAL RESULTStransmission range • Two sensor nodes with the antennas in a back to back disposition • Sequence numbers in each packet transmitted • Vary the distance between the nodes, keep the track of the number of lost packets • Assume threshold as the distance at which the percentage of received packets are below 85% • Transmission range is approximately 55 m for mica2 and 135 m for mica2dot.

  13. EXPERIMENTAL RESULTStransmission range cont.

  14. EXPERIMENTAL RESULTStransmission range cont. • Factors that may affect the transmission range • Transmission power • Orientation of the antenna • Data rate • Sensor nodes location with respect to the ground • Environmental conditions • Transmission power: more than linear increase this increase for both kinds of motes. • At the maximum transmission power 5dBm • transmission range: 70 m for mica2 • Transmission range: 230 m for mica2dot

  15. EXPERIMENTAL RESULTStransmission range cont. • Influence of the antenna • Change the relative antennas’ disposition to see the effect of the communication quality in terms of received packets • mica2 antennas are very directional • mica2dot nodes are resistant

  16. EXPERIMENTAL RESULTStransmission range cont. • Influence of the data rate • Inversely proportional in IEEE 802.11 wireless networks • Does not have a significant influence on in mica2 and mica2dot • Different scale of data rates • Motes: Kbps whereas • IEEE802.11 stations: Mbps.

  17. EXPERIMENTAL RESULTStransmission range cont.

  18. EXPERIMENTAL RESULTStransmission range cont. • Effect of sensor node’s height • When the nodes are close to the ground under 1 meter, significant power loss. • This loss is due to the interference between the ground.

  19. EXPERIMENTAL RESULTStransmission range cont. • Influence of environmental conditions • Slight variations of temperature or humidity do not have any significant influence • In the presence of fog or rain, we saw that transmission range decreased significantly • Due to signal attenuation caused by the interference of fog and rain particles with the electromagnetic waves

  20. EXPERIMENTAL RESULTScarrier sensing range • Fixed distance between the nodes in a couple • Vary the distance between the two couples • Until no correlation is measured between the couples • Until Throughput achieved =4.4 Kbps

  21. EXPERIMENTAL RESULTScarrier sensing range • 275 m :end of the carrier sensing range • Minor interference • 450 m: interference becomes negligible

  22. MAC PROTOCOLS • S-MAC • Reduce energy consumption caused by idle listening • Schedule coordinated transmission and listen periods • Overhead due to coordination and schedule maintenance. • B-MAC • Wake up for a very small time and sleep for a longer time. • Poll the channel, if nothing interesting, go back to sleep • Long preamble guaranteed to intersect with polling • SCP-MAC • Ultra-low duty cycle • Synchronizing the polling times

  23. DATA DISSEMINATION • PUSH BASED STRATEGY • Nodes detecting the interesting event broadcast the relevant information • Efficient when there is constant need of information • Broadcast bandwidth is wasted when the demand for the information is low • PULL BASED STRATEGY • Querier broadcasts a query for the information when it is needed. • Nodes that have the relevant information send the information back. • Communication takes place only when it is needed.

  24. DATA DISSEMINATION cont. • COMB-NEEDLE STRATEGY • Integrates both push and pull based techniques • Each sensor node pushes its data through some number of • The querier pulls the data in a certain neighborhood • In most cases it is more efficient than both pure push and pure pull strategies.

  25. Any Questions? THANK YOU!

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