Wireless Sensor Networks

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Wireless Sensor Networks:

Wireless Sensor Networks A wireless sensor network (WSN) is a wireless network consisting of spatially distributed autonomous devices that use sensors to monitor physical or environmental conditions. These autonomous devices, or nodes, combine with routers and a gateway to create a typical WSN system. The distributed measurement nodes communicate wirelessly to a central gateway, which provides a connection to the wired world where you can collect, process, analyze, and present your measurement data.

Common Wireless Sensor Network Architecture:

Common Wireless Sensor Network Architecture

APPLICATIOns of wsn:

APPLICATIOns of wsn Remote monitoring Industrial measurements Indoor monitoring Power Quality and Consumption monitoring Solar monitoring Machine condition monitoring Process monitoring ….... …………….. ………………

Routing in WSN:

Routing in WSN They can be divided into two main categories Address Centric: Finding shortest path between pairs of addressable end-nodes. Data Centric : Finding routes from multiple sources to a single sink, allowing data aggregation

Address Centric:

Address Centric Source 1 Sink A C B Source 2

Data Centric:

Data Centric Source 1 A C B – aggregates data from 1 & 2 Source 2

Various Routing Protocols:

Various Routing Protocols Classic Flooding Gossiping Ideal Dissemination SPIN

Classing Flooding:

Classing Flooding B D E F G C A Send data to all neighbors.

Gossiping:

Gossiping Gossiping is an alternative to the classic flooding approach that uses randomization to conserve energy. At every step each node only forwards data on to one neighbor, which it selects randomly. After node D receives the data, it must forward the data back to sender (B), otherwise the data would never reach node C A B D C

Ideal Dissemination:

Ideal Dissemination Ideal Dissemination of observed data a and c. Each node in the figure is marked with its initial data and boxed number represent the order in which data is disseminated. In Ideal dissemination both implosion caused by B and C’s common neighbor and overlap caused by A and C’s overlapping initial data item do not occur. A B C D a,c a c c a

SPIN: Sensor Protocols for Information Negotiation:

SPIN: Sensor Protocols for Information Negotiation One of the most dominant form of routing in the wireless sensor networks. Name data, using meta-data Meta Data for each sensor data Same senor data -> same meta-data Different sensor data -> different meta-data Size of meta-data << Size of actual data Uses three types of messages: ADV – advertise data REQ – request for data DATA – data message, contains actual sensor data

SPIN1 and SPIN2:

SPIN1 and SPIN2 SPIN1 : Three way handshaking protocol. ADV, REQ, DATA. Each sensor node has resource manager Keeps track of resource consumption Applications probe the manager before any activity Cut down activity to save energy SPIN2 : energy constraint Adds energy-conservative heuristic to the SPIN1 protocol. Node initiates three stage protocol, only if it has enough energy to complete it. If below energy threshold, node can still receive messages, cannot send/ recv DATA messages

Sun spots:

Sun spots Sun SPOTs (Sun Small Programmable Object Technology) are small, wireless, battery-powered devices…….. Developed at Sun Labs to explore the next frontier of network computing……. Sun SPOTs are powered by a specially designed small-footprint Java virtual machine, called, that can host multiple applications concurrently, and requires no underlying operating system.

Sun spots Continue:

Sun spots Continue Stackable boards include application-specific sensors and actuators such as accelerometers, light detectors, temperature sensors, LEDs, push buttons and general I/O pins. The devices can be duty cycled to run for months on a single charge of their rechargeable battery.

Transmission & reception:

Transmission & reception It uses an integrated radio transceiver, the TI CC2420……… IC contains a 2.4GHz RF transmitter/receiver with digital direct sequence spread spectrum (DSSS) baseband modem with MAC support Separate TX and Rx 128 byte FIFOs Tx output power setting from -24dBm to 0dBm Rx sensitivity is -90dBm Accurate 16MHz crystal is used for frequency generation

Sensors:

Sensors There are different sensors in SUN SPOT Temperature Sensor Light Sensor Accelerometer

Temperature Sensor:

Temperature Sensor The ADT7411 ADC contain temperature sensor that is capable of tepmrature in range -40 t0 +125 degree Celsius with an accuracy of 0.25 degree Celsius.... +ve temp = ADC/4 (when ADC<512) -ve temp = (ADC-1024)/4 (when ADC>=512)

Light Sensor:

Light Sensor Light sensor convert light into voltage ranging from 0.1v to 4.3v (dark to light) Switching time is approximately 30 micro second

Accelerometer :

Accelerometer Inertial sensor LIS3L02AQ is used For each axis, max sample rate is 160Hz The accelerometer has three voltage outputs Vout_x, Vout_y, Vout_z representing acceleration in 3-axis… The force accelerating the SPOT in any dimension in g-force

flooding:

flooding

flooding:

flooding

flooding:

flooding

flooding:

flooding

flooding:

flooding

flooding:

flooding

flooding:

flooding

flooding:

flooding

Route request in AODV:

Route request in AODV

Route request in AODV:

Route request in AODV

Route request in AODV:

Route request in AODV

Reverse path setup in AODV:

Reverse path setup in AODV

Reverse path setup in AODV:

Reverse path setup in AODV

Reverse path setup in AODV:

Reverse path setup in AODV

Route reply in AODV:

Route reply in AODV

Forward path setup in AODV:

Forward path setup in AODV

Data delivery in AODV:

Data delivery in AODV

What is ZigBee?:

Copyright 2005 Software Technologies Group, Inc. All Rights Reserved. What is ZigBee ? A standard for mesh networking Built on the IEEE 802.15.4 standard Reliability through meshed connectivity Designed for low power applications Very long battery life Low data rate 20-250Kb/sec (depending on band) Very Secure AES-128 encryption available Self configuring Allows ad hoc networks Ease of installation and configuration

ZigBee Target Markets:

Copyright 2005 Software Technologies Group, Inc. All Rights Reserved. Security HVAC Lighting Control Access Control Lawn & Garden Irrigation Asset Mgt Process Control Environmental Energy Mgt Patient monitoring Fitness monitoring Security HVAC AMR Lighting Control Access Control TV VCR DVD/CD RF Remotes ZigBee Target Markets ZigBee Wireless Control that Simply Works RESIDENTIAL/ LIGHT COMMERCIAL CONTROL CONSUMER ELECTRONICS PC & PERIPHERALS INDUSTRIAL CONTROL PERSONAL HEALTH CARE BUILDING AUTOMATION Chart Copyright ZigBee Alliance 2004

The ZigBee Standard:

Copyright 2005 Software Technologies Group, Inc. All Rights Reserved. The ZigBee Standard Protocol Supports meshing of 802.15.4 nodes Support for rapid joining and leaving the network (joining in <30ms) Support for route discovery and route failure recovery Services Device and Service discovery Standardized Device Profiles

ZigBee in the wireless world:

Copyright 2005 Software Technologies Group, Inc. All Rights Reserved. ZigBee in the wireless world Chart Copyright ZigBee Alliance 2004

ZigBee in the wireless world:

Copyright 2005 Software Technologies Group, Inc. All Rights Reserved. ZigBee in the wireless world Band – 868, 902-928MHz, and 2.4GHz Topology – Ad-hoc, Star, Point to Point, Mesh Data Rate – 20/40Kb/s and 250Kb/s Power Consumption – Very Low Range – 10-100+ meters Security – very high; AES-128 level encryption Size – up to 64K nodes in a single logical network