Sensor Networks & TinyDB Author: Roman Kolcun Supervisor: - PowerPoint PPT Presentation

Sensor Networks & TinyDB Author: Roman Kolcun Supervisor: Julie A. McCann

Index  Sensor Motes  Sensor Networks  Real world deployments  TinyDB 2

What a Sensor Can Sense? 3

What a Sensor Can Sense?  Temperature  Heart Rate  Humidity  Motion  Acceleration  Toxins  Noise  Nutrients  Light  Glucose Level  Magnetic Field  Oxygen Level  Gravity  Hormones  Pressure  Proteins 4

Sensor Mote  CPU ? 5

Sensor Mote  CPU  4 MHz  8 bit ATmega 128L, RISC  Memory ? 6

Sensor Mote  CPU  4 MHz  8 bit ATmega 128L, RISC  Memory  128KB Program Flash Memory  4KB RAM  512KB Flash – serial access, max. 10-100k rewritten  Wireless ? 7

Sensor Mote  CPU  4 MHz  8 bit ATmega 128L, RISC  Memory  128KB Program Flash Mem.  4KB RAM  512KB Flash – serial access, max. 10-100k rewritten  Wireless  IEEE 802.15.4 - 2.4GHz  250kbps 8  70 – 100m outdoor, 20 – 30m indoor

Beastie – Imperial  8k bytes Flash program memory  1k byte SRAM  512 bytes EEPROM  4MHz  FM radio at 434.65MHz  10kbps maximum data rate (run at 5kbps as standard)  Maximum range 500m 9

1 mm 3 Sensor  Designed at Michigan University  Measures pressure in an eye every 15 minutes  Average Power Consumption 15 nW  To charge batteries:  10 hours of artificial light  1.5 hours of sun light 10

Power Consumption  Typically supplied by small batteries  1000 – 3000 mAh  1 mAh – 1 milliamp current for 1 hour  Power = Watts (W) = Amps (A) * Volts (V)  Energy = Joules (J) = W * time  Power consumption  Processor: 8mA active, <15μA sleep  Radio: 19.7mA receive, 11 – 17.4mA xmit, ~20ms/packet  Sensor: 1μA – 100's mA, 1μs – 1s to sample 11

Example  Battery: 1000mAh  How long a node can last and how much data can a node receive? 12

Example  Battery: 1000mAh  How long a node can last and how much data can a node receive? 1000mAh / 19.7mA = ~50.7h 50.7h = 182 741s * 250kbps = ~5.7MB in real world approx. half of it = 2.85MB 13

Example  Battery: 1000mAh  Sense 1 value every 30 seconds, receive 1 packet and send 1 packet. How long will battery last? 14

Example  Battery: 1000mAh  Sense 1 value every 30 seconds, receive 1 packet and send 1 packet. How long will battery last? 8+29*0.015+1+19.7*0.02+13*0.02 = = ~10mA/30s = ~ 0.3363 mA/s 1000mAh = 3 600 000 mAs / 0.3363 = ~124 days 15

Sensor Networks - Problems  Lossy, Ad-hoc radio communication  Really lossy radio communication  Node / link failures  Severe power constraints  Asymmetric links – if I can hear you, it does not mean you can hear me  Interference  Hidden node problem 16

Sensor Networks 17

Sensor Networks 18

Sensor Networks - Problems  Duty cycling  Time synchronization  Node / link failure 19

Duty Cycling epoch time … zzz … … zzz … time wake-up period 20

Real World Deployments  Great Duck Island  temperature  relative humidity  infra-red termophile 21

Real World Deployments  Golden Gate Bridge  vibrations  temperature 22

Redwood Humidity vs. Time 36m 101 104 109 110 111 33m: 111 95 32m: 110 85 Rel Humidity (%) 30m: 109,108,107 75 65 55 20m: 106,105,104 45 35 10m: 103, 102, 101 Temperature vs. Time 33 28 23 18 13 8 7/7/03 7/7/03 7/7/03 7/7/03 7/7/03 7/8/03 7/8/03 7/8/03 7/8/03 7/8/03 7/8/03 7/9/03 7/9/03 7/9/03 7/9/03 9:40 13:11 16:43 20:15 23:46 3:18 6:50 10:21 13:53 17:25 20:56 0:28 4:00 7:31 11:03 Date 23

Imperial Deployment  Mobile Node (Mule) Experiment 24

Other Deployments  Monitoring Space  environmental and habitat monitoring (Duck Island, Redwood Trees)  precision agricultures  climate control  surveillance  intelligent alarms 25

Other Deployments (cont.)  Things  structural monitoring  ecophysiology  condition based maintenance (plane, bridges, buildings, pipes)  medical diagnostics  terrain mapping 26

Other Deployments (cont.)  Interactions with things and encompassing space  monitoring wildlife habitats  disaster management  emergency response  ubicomp  process flow 27

Motivations for TinyDB  Create an application which measures temperature. Make an average of temperatures over 15°C. 28

Motivations for TinyDB  Create an application which measures temperature. Make an average of temperatures over 15°C.  How would you change the application to make an average of temperatures over 20°C ? 29

Motivations for TinyDB  Create an application which measures temperature. Make an average of temperatures over 15°C.  How would you change the application to make an average of temperatures over 20°C ?  Recode the application and manually update every node.  Think about it while programming the application and let it accept commands from the basestation  Use TinyDB 30

TinyDB  Supports a subset of Stream SQL  Whole network could be seen as ”sensor” table  Query syntax: SELECT <aggregates>, <attributes> [FROM {sensors} | {buffer}] [WHERE <predicates>] [GROUP BY <expression>] [SAMPLE INTERVAL <const> | ONCE] [INTO buffer] 31 [TRIGGER ACTION <command>]

TinyDB  Example: SELECT light, mag FROM sensors WHERE light > c1 AND mag > c2 SAMPLE INTERVAL 1s [FOR 3600s] 32

TinyDB E(sampling mag) » E(sampling light)  Example: 1500 μJ vs 90 μJ SELECT light, mag FROM sensors In which order the predicates should be evaluated? WHERE light > c1 AND mag > c2 SAMPLE INTERVAL 1s 33

TinyDB  Do we need to notify all sensors in the network? SELECT light FROM sensors WHERE node_id > 20 SAMPLE INTERVAL 10s 34

What if the Result Depends on More than One Node? 35

What if the Result Depends on More than One Node? (cont.) 36

What We Do  Adjust power transmission in order to minimise interference using game theory  Duty-cycling  Time synchronization  Mules  In-network data processing (joining data & data filtering) 37

References [1] Decentralised & Volatile Self-Adaptive,Self Organising WSNs by Julie A. McCann [2] Implementation and Research Issues in Query Processing for Wireless Sensor Networks by Wei Hong & Sam Madden [3] Modelling the Golden Gate Bridge using Wireless Sensor Networks by Guilherme Rocha, Shamim Pakzad and Bin Yu [4] http://www.coa.edu/greatduckisland.htm – College of the Atlantic – Great Duck Island Project 38

Where You Can Find Us  Julie A. McCann: jamm@doc.ic.ac.uk  Roman Kolcun: rk1208@doc.ic.ac.uk  Lab: Huxley Building, 563 39