samedi 28 janvier 2012 Architecture

(1)

Architecture

samedi 28 janvier 2012

(2)

Sensor Node Architecture

Battery

DC-DC

Sensor

ADC MCU

Memory

Radio

(3)

Available Devices

• MicaZ (Crossbow)

• 2.94 GHz IEEE 802.15.4 Zigbee radio

• 128 KB program memory

• 512 KB data memory

• ^{8 mA draw}

(4)

Available Devices

• Tmote Sky/invent (Moteiv)

• 2.94 GHz IEEE 802.15.4 Zigbee radio

• 8MHz processor

• ^{10 KB RAM}

• 48 KB Flash

(5)

Available Devices

• Stargate (Crossbow)

• Wired Ethernet

• Wifi/Cellular via PCMCIA

• INTEL PXA 255

• Linux Kernel

Environmental Monitoring Application Note

Data Interval (minutes)

Average MICA2 or MICA2DOT Current

(µA)

1 677

3 315

6 196

The XMesh network has been extensively tested both at indoor and outdoor locations. In a typical indoor test, nodes were placed at every 300 sq ft. to cover a 10,000 sq ft facility. To simulate larger distance between nodes, the radio transmit power was turned down to -6dBm. In outdoor tests nodes were spread across several acres of rugged terrain with an average density of 1 mote per 10,000 sq ft and at full radio power. Statistical analysis across many deployments shows on average greater than 90% of all traffic generated at any node will be collected at the base station without the use of end-end acknowledgements.

Stargate Base Station

Figure 4. Stargate gateway as a base station

The Crossbow Stargate gateway and microserver is an embedded Linux computer designed to be the primary access point for wireless sensor networks. The Stargate’s small form factor,

reliability, and optional communication interfaces makes it ideal for remote, environmental monitoring. A base station mote (MICA2) is connected to the 51-pin connector on the Stargate.

A resident program, XListen, takes an input stream of wireless sensor data from the base station mote and stores it in a local Postgres database.

The Crossbow Stagate can be connected to a wide-area or back-haul network in one of the following ways:

! Wired Ethernet connection

! WiFi, using a Compact Flash card (Netgear MA701, AmbicomWL1100C-CF, etc.)

! Long Range WiFi using PCMCIA card (ZComax or SMC Wireless SMC2532W-B).

! Cell phone modem card (Sierra Wireless Aircard 555D) for remote cellular access.

Page 7

(6)

Sensors

• Exterioceptors: information about the surroundings

• Proprioceptors: information about the

internal workings

(7)

Sensors

Measurand Transduction

Physical Pressure Piezoresistive, capacitive

Temperature Thermistor,

thermomechanical, thermocouple

Humidity Resistive, capacitive

Flow Pressure change, thermistor

(8)

Sensors

Measurand Transduction

Motion Position E-mag, GPS, contact

Velocity Doppler, Hall effect, optoelectronic

Angular velocity Optical encoder

(9)

Sensors

Measurand Transduction

Contact Strain Piezoresistive

Force Piezoelectric, piezoresistive

Torque Piezoresistive, optoelectronic

Vibration Piezoresistive, piezoelectric, optical fiber, sound,

ultrasound

(10)

Sensors

Measurand Transduction

Presence Tactile Contact switch, capacitive

Proximity Hall effect, capacitive, magnetic, seismic, acoustic,

RF

Distance E-mag (sonar, radar, lidar),

magnetic, tunelling

(11)

Sensors

Measurand Transduction

Biochemical Agents biochemical transduction

Identification Personal

features ^Vision

Personal ID Fingerprints, retinal scan, voice, heat plume, vision,

motion analysis

(12)

Sensor Node

Operating System

• TinyOS concepts

• Scheduler + Graph of components

• ^Component

• Constrained storage model

• Very Lean multithreading

• Efficient Layering

(13)

TinyOS Component

Commands

Events

Task State

Provides

Uses

(14)

TinyOS Application

Route Map Router Sensor Application

Active Messages

Radio Packet

Serial

Packet Temp Photo

Radio Byte

Application

Packet

Byte

(15)

Programming TinyOS

• TinyOS is written in NesC

• Applications are written as system components

• Syntax for concurrency and storage model

• Compositional support

• Separation of definition and linkage

(16)

Simulating TinyOS

• Target platform: TOSSIM

• Native instruction set

• Event driven execution mapped to event drivent simulator

• Storage model mapped to virtual nodes

• Radio and environmental models

(17)

Overview

(18)

Issues and Solutions

• Localization

• ^Routing

• Medium Access Control

• Applications

(19)

Localization

(20)

Localization

• Fine-grained

• ^Timing

• Signal strength

• Signal pattern matching

• Directionality

• Coarse-grained

(21)

Triangulation

(22)

Triangulation

C

(23)

Triangulation

A B

C

distance

a b

distance

(24)

Trilateration

(25)

Trilateration

r ₁

(26)

Trilateration

r ₁

r ₂

(27)

Trilateration

r ₁

r ₂

r ₃

(28)

Trilateration

r ₁

r ₂

r ₃

d

(29)

Trilateration

r ₁

r ₂

r ₃

d j

(30)

Trilateration

r ₁

r ₂

r ₃

d j

i

(31)

Trilateration

r ₁

r ₂

r ₃

d j

i

r ₁ ² = x ² + y ² + z ²

(32)

Trilateration

r ₁

r ₂

r ₃

d j

i

r ₁ ² = x ² + y ² + z ²

r ₂ ² = (x − d) ² + y ² + z ²

(33)

Trilateration

r ₁

r ₂

r ₃

d j

i

r ₁ ² = x ² + y ² + z ²

r ₃ ² = (x − i) ² + (y − j ) ² + z ² r ₂ ² = (x − d) ² + y ² + z ²

(34)

Trilateration

r ₁

r ₂

r ₃

d j

i

(35)

Trilateration

r ₁

r ₂

r ₃

d j

i

x = r ₁ ² − r ₂ ² + d ² 2d

(36)

Trilateration

r ₁

r ₂

r ₃

d j

i

x = r ₁ ² − r ₂ ² + d ² 2d

y = r ₁ ² − r ₃ ² + (x − i) ²

2j + j

2 + x ²

2j

(37)

Trilateration

r ₁

r ₂

r ₃

d j

i

x = r ₁ ² − r ₂ ² + d ² 2d

y = r ₁ ² − r ₃ ² + (x − i) ²

2j + j

2 + x ² 2j z = �

r ₁ ² − x ² − y ²

(38)

Centroid

(39)

Centroid

(40)

Centroid

(41)

Routing

(42)

Routing

• Classical flooding

• ^Implosion

• Resource management

• Negociation based protocols

• ^SPIN

• Directed Diffusion

(43)

Negociation Based Protocols

• SPIN: Sensor Protocols for Information via Negociation

• Information descriptors for negociation prior to data transmission

• Negociation relates to available energy

(44)

SPIN

• ADV: advertize that new data is available and described

• REQ: request to receive data

• DATA: actual data

(45)

SPIN-PP

S R

(46)

SPIN-PP

S R

ADV

(47)

SPIN-PP

S R

ADV

REQ

(48)

SPIN-PP

S R

ADV

REQ

DATA

(49)

SPIN-EC

S R

(50)

SPIN-EC

S R

ADV

(51)

SPIN-EC

S R

ADV

REQ

(52)

SPIN-EC

S R

ADV

REQ

DATA

(53)

SPIN-EC

S R

(54)

SPIN-EC

S R

ADV

(55)

SPIN-EC

S R

ADV

R

(56)

SPIN-BC

S

R

(57)

SPIN-BC

S

R

R R

ADV

(58)

SPIN-BC

S

R

(59)

SPIN-BC

S

R

R R

REQ REQ

(60)

SPIN-BC

S

R

(61)

SPIN-BC

S

R

R R

DATA

DATA DATA

(62)

SPIN-BC

S

R

(63)

Directed Diffusion

• Destination-initiated (sink) reactive routing technique

• Tasks are described by attribute-value pairs (interests)

• All nodes maintain interest cache for each requested interest

(64)

Interests

item name value

type four-legged animal

interval 20 ms

duration 10 s

rect [-100, 100, 200, 400]

(65)

Returned Data

item name value

type four-legged animal instance [125, 220]

intensity 0.6

confidence 0.85

timestamp 01:20:40

(66)

Directed Diffusion

N

N N

(67)

Directed Diffusion

S N

N

N N

N

(68)

Directed Diffusion

N

N N

(69)

Directed Diffusion

S N

N

N N

N

(70)

Directed Diffusion

N

N N

(71)

Directed Diffusion

S N

N

N N

N

(72)

Directed Diffusion

N

N N

(73)

Directed Diffusion

S N

N

N N

N

(74)

Interest Cache

• Periodically purged

• No information about sink

• Gradient table

• rate per neighbor

• ^timestamp

• ^expiration

(75)

Interest Forwarding

• When new received, add to cache

• Simplest policy: rebroadcast interest

• No way of distinguishing new interests from repeated ones

• Set up (very low rate) gradients between all neighbors

• Must distinguish between neighbors

(76)

Message propagation

• A node matching an interest generates replies at desired rate

• When receiving a reply, lookup interest cache

• Forward along given route(s) if found, drop otherwise

• Loop prevention

(77)

Directed Diffusion

S E

N

N N

N

(78)

Directed Diffusion

E

N

N N

(79)

Directed Diffusion

S E

N

N N

N

(80)

Directed Diffusion

E

N

N N

(81)

Directed Diffusion

S E

N

N N

N

(82)

Directed Diffusion

E

N

N Reinforcement N

request

(83)

Directed Diffusion

S E

N

N N

N

Reinforcement request

(84)

Directed Diffusion

E

N

N Reinforcement N

request

(85)

Directed Diffusion

S E

N

N N

N

Reinforcement request

(86)

Directed Diffusion

E

N

N Reinforcement N

request

(87)

Reinforcement

• Sink can reissue the same request with a higher rate

• “Draw down” higher quality data from a particular neighbor

• Other nodes react when receiving

• “Outflow” increased, must reinforce another node to increase “inflow”

(88)

Directed Diffusion

E

N

N S

(89)

Directed Diffusion

S E

N

N S

N

(90)

Directed Diffusion

E

N

N S

(91)

Directed Diffusion

S E

N

E

N N

N

(92)

Directed Diffusion

E

N

E

N N

(93)

Directed Diffusion

S E

N

E

N N

N

(94)

Directed Diffusion

E

N

N N

(95)

Directed Diffusion

S E

N

N N

N

(96)

Directed Diffusion

E

N

N N

(97)

Directed Diffusion

S E

N

N N

N

(98)

Directed Diffusion

E

N

N N

(99)

Directed Diffusion

S E

N

N N

N

(100)

Directed Diffusion

• Local algorithm policies

• Propagating interests

• flood, cache information, GPS

• Setting up gradients

• first heard neighbor, highest energy

neighbor

(101)

Directed Diffusion

• Local algorithm policies

• Data transmission

• single path, striped multi-path, multiple sources, etc.

• Reinforcement

• observer losses, resources levels, etc.

(102)

Energy Aware Routing

• Similar to Directed Diffusion

• destination initiated

• initial flooding to discover routes

• several sub-optimal paths can be used

(with a probabilistic distribution)

(103)

Energy Aware Routing

S E

N

N N

N

(104)

Energy Aware Routing

E

N

N N

(105)

Energy Aware Routing

S E

N

N N

N

0.3 0.3 0.4

1 1

1

(106)

Medium Access

Control

(107)

Classical Approaches

• FDMA: Frequency division multiple access

• TDMA: Time division multiple access

• CDMA: Code division multiple access

• CSMA: Carrier sense multiple access

• CD: Collision detection

• CA: Collision avoidance

(108)

Classical Approaches

• FDMA: Frequency division multiple access

• TDMA: Time division multiple access

• CDMA: Code division multiple access

• CSMA: Carrier sense multiple access

• CD: Collision detection

• CA: Collision avoidance

One frequency available

(109)

Classical Approaches

• FDMA: Frequency division multiple access

• TDMA: Time division multiple access

• CDMA: Code division multiple access

• CSMA: Carrier sense multiple access

• CD: Collision detection

• CA: Collision avoidance

One frequency available

One code available

(110)

Classical Approaches

• FDMA: Frequency division multiple access

• TDMA: Time division multiple access

• CDMA: Code division multiple access

• CSMA: Carrier sense multiple access

• CD: Collision detection

• CA: Collision avoidance

One frequency available

One code available

Can’t listen while transmitting

(111)

Hidden Terminal problem

S1 R S2

(112)

Hidden Terminal problem

S1 R S2

(113)

Hidden Terminal problem

S1 R S2

(114)

Hidden Terminal problem

S1 R S2

(115)

Hidden Terminal problem

S1 R S2

(116)

Exposed Terminal Problem

R1 S1 S2 R2

(117)

Exposed Terminal Problem

R1 S1 S2 R2

(118)

Exposed Terminal Problem

R1 S1 S2 R2

(119)

Exposed Terminal Problem

R1 S1 S2 R2

(120)

Exposed Terminal Problem

R1 S1 S2 R2

(121)

IEEE 802.11 RTS/CTS

S R

(122)

IEEE 802.11 RTS/CTS

S R

ADV RTS

(123)

IEEE 802.11 RTS/CTS

S R

ADV

REQ

RTS

CTS

(124)

IEEE 802.11 RTS/CTS

S R

ADV

REQ

DATA

RTS

CTS

(125)

IEEE 802.11 RTS/CTS

S1 R S2

(126)

IEEE 802.11 RTS/CTS

S1 R S2

(127)

IEEE 802.11 RTS/CTS

S1 R S2

(128)

IEEE 802.11 RTS/CTS

S1 R S2

(129)

IEEE 802.11 RTS/CTS

S1 R S2

(130)

IEEE 802.11 RTS/CTS

S1 R S2

(131)

IEEE 802.11 RTS/CTS

S1 R S2

(132)

IEEE 802.11 RTS/CTS

S1 R S2

(133)

IEEE 802.11 RTS/CTS

S1 R S2

(134)

IEEE 802.11 RTS/CTS

R1 S1 S2 R2

(135)

IEEE 802.11 RTS/CTS

R1 S1 S2 R2

(136)

IEEE 802.11 RTS/CTS

R1 S1 S2 R2

(137)

IEEE 802.11 RTS/CTS

R1 S1 S2 R2

(138)

IEEE 802.11 RTS/CTS

R1 S1 S2 R2

(139)

IEEE 802.11 RTS/CTS

R1 S1 S2 R2

(140)

IEEE 802.11 RTS/CTS

R1 S1 S2 R2

(141)

Energy Consumption

Idle Receive Transmit

[1] 1 1.05 1.4

[2] 1 2 2.5

[1] LAN MAN Standards Committee of the IEEE Computer Society, Wireless LAN medium access control (MAC) and

physical layer (PHY) specification.

[2]Mark Stemm and Randy H. Katz, “Measuring and

Reducing Energy Consumption of Network Interfaces in Hand-held Devices”

(142)

Duty Cycling

• Reduces idle listening time

• Sensors switch between sleep and active mode

• Suits low traffic networks

• If data rate is very low, it is not necessary to keep sensors listening all the time

•

(143)

Duty Cycling

Sleeping Listening 1 second

(144)

Duty Cycling

Sleeping Listening 1 second

Data sampling

(145)

Duty Cycling

Sleeping Listening 1 second

Data sampling

Extra Latency

(146)

Duty Cycling

Sleeping Listening

A

B

(147)

Duty Cycling

Sleeping Listening

A

B

Message Sending

(148)

Duty Cycling

Sleeping Listening

A

B

Message Sending Extra Latency

(149)

Duty Cycling

Sleeping Listening

A

B

Sleeping Listening

Listening Sleeping

(150)

Duty Cycling

Sleeping Listening

A ^Sleeping ^Listening

Sleeping Listening

B ^Sleeping ^Listening

(151)

Duty Cycling

Sleeping Listening

A ^Sleeping ^Listening

Sleeping Listening

B ^Sleeping ^Listening

long period

(duty period * #of hops)

(152)

Time Synchronization

(153)

Time synchronization

• Definition: providing a common time scale for local clocks of nodes in the

network

• Stamp event, duration between events, order events

• No global clock of shared memory

(154)

Time Synchronization

C _p (t) = a _p t + d _p a _p : clock frequency

d _p : oﬀset

(155)

Remote Clock Reading

B

A T ₀ T ₁

T _B

(156)

Remote Clock Reading

B

A T ₀ T ₁

T _B

T _B (T ₁ ) = T _B + T ₁ − T ₀

2

(157)

Time Transmission

B

A

T ₁

T ₁ T ₂

T ₂

T _n

T _n R ₁ R ₂ R _n

(158)

Time Transmission

B

A

T ₁

T ₁ T ₂

T ₂

T _n

T _n R ₁ R ₂ R _n

T _B (R _n ) = R _n −

� 1 n

� n

R _i − 1 n

� n

T _i

�

+ d

(159)

Offset Delay Estimation

B

A T ₀

T ₀

T ₁ T ₂

T ₃

T ₀ , T ₁ , T ₂

(160)

Offset Delay Estimation

B

A T ₀

T ₀

T ₁ T ₂

T ₃

T ₀ , T ₁ , T ₂

∆ = (T ₁ − T ₀ ) − (T ₃ − T ₂ )

2

(161)

Offset Delay Estimation

B

A T ₀

T ₀

T ₁ T ₂

T ₃

T ₀ , T ₁ , T ₂

∆ = (T ₁ − T ₀ ) − (T ₃ − T ₂ )

2 d = (T ₁ − T ₀ ) + (T ₃ − T ₂ ) 2

Drift Offset

(162)

Set Valued Estimation

B

A T ₀

T _B

T _r

(163)

Set Valued Estimation

B

A T ₀

T _B

T _r

C _A (t) = a _AB C _B (t) + d _AB

(164)

Set Valued Estimation

B

A T ₀

T _B

T _r

(t) = (t) +

T ₀ < a _AB T _B + d _AB T _r > a _AB T _B + d _AB

(165)

Set Valued Estimation

C _A (t)

C _B (t)

(166)

Set Valued Estimation

T ₀ ₁ T _r ₁

C _A (t)

(167)

Set Valued Estimation

T ₀ ₁ T _r ₁ d _AB

d _AB

C _A (t)

C _B (t)

(168)

Set Valued Estimation

T ₀ ₁ T _r ₁ d _AB

d _AB d _AB

C _A (t)

(169)

Time Synchronization

(170)

Conclusion

(171)

Sensor Networks

• Driven by applications

• Connexion between Computer Science and Biology, Environment, Rescue, etc.

• Hard problems yet to be solved

samedi 28 janvier 2012 Architecture

Architecture

Sensor Node Architecture

Battery

DC-DC

Sensor

ADC MCU

Memory

Radio

Available Devices

• MicaZ (Crossbow)

• 2.94 GHz IEEE 802.15.4 Zigbee radio

• 128 KB program memory

• 512 KB data memory

• 8 mA draw

Available Devices

• Tmote Sky/invent (Moteiv)

• 2.94 GHz IEEE 802.15.4 Zigbee radio

• 8MHz processor

• 10 KB RAM

• 48 KB Flash

Available Devices

• Stargate (Crossbow)

• Wired Ethernet

• Wifi/Cellular via PCMCIA

• INTEL PXA 255

• Linux Kernel

Sensors

• Exterioceptors: information about the surroundings

• Proprioceptors: information about the

internal workings

Sensors

Measurand Transduction

Physical Pressure Piezoresistive, capacitive

Temperature Thermistor,

thermomechanical, thermocouple

Humidity Resistive, capacitive

Flow Pressure change, thermistor

Sensors

Measurand Transduction

Motion Position E-mag, GPS, contact

Velocity Doppler, Hall effect, optoelectronic

Angular velocity Optical encoder

Sensors

Measurand Transduction

Contact Strain Piezoresistive

Force Piezoelectric, piezoresistive

Torque Piezoresistive, optoelectronic

Vibration Piezoresistive, piezoelectric, optical fiber, sound,

ultrasound

Sensors

Measurand Transduction

Presence Tactile Contact switch, capacitive

Proximity Hall effect, capacitive, magnetic, seismic, acoustic,

RF

Distance E-mag (sonar, radar, lidar),

magnetic, tunelling

Sensors

Measurand Transduction

Biochemical Agents biochemical transduction

Identification Personal

features Vision

Personal ID Fingerprints, retinal scan, voice, heat plume, vision,

motion analysis

Sensor Node

Operating System

• TinyOS concepts

• Scheduler + Graph of components

• Component

• Constrained storage model

• Very Lean multithreading

• Efficient Layering

TinyOS Component

Commands

Events

Task State

Provides

Uses

TinyOS Application

Route Map Router Sensor Application

• ^{8 mA draw}

• ^{10 KB RAM}

features ^Vision

• ^Component

• ^Routing

• ^Timing

r ₁

r ₁

r ₂

r ₁

r ₂

r ₃

r ₁

r ₂

r ₃

r ₁

r ₂

r ₃

r ₁

r ₂

r ₃