Wireless sensor networks

ABSTRACT:-

          Wireless sensor networks are attracting increased interest for a wide range of applications, such as environmental monitoring and vehicle tracking. However, developing sensor network applications is notoriously difficult, due to extreme resource limitations of nodes, the unreliability of radio communication, and the necessity of low power operation. Our goal is to simplify application design by providing a set of programming primitives for sensor networks that abstract the details of low-level communication, data sharing, and collective operations.

          We present abstract regions, a family of spatial operators that capture local communication within regions of the network, which may be defined in terms of radio connectivity, geographic location, or other properties of nodes. Regions provide interfaces for identifying neighboring nodes, sharing data among neighbors, and performing efficient reductions on shared variables. In addition, abstract regions expose the tradeoff between the accuracy and resource usage of communication operations. Applications can adapt to changing network conditions by tuning the energy and bandwidth usage of the underlying communication substrate. We present the implementation of abstract regions in the TinyOS programming environment, as well as results demonstrating their use for building adaptive sensor network applications. 

  INTRODUCTIONTypical multi-hop wireless sensor network architecture

A wireless sensor network (WSN) consists of spatially distributed autonomous sensors to monitor physical or environmental conditions, such as temperature, sound,vibration, pressure, motion or pollutants and to cooperatively pass their data through the network to a main location. The  more modern networks are bi-directional, also enabling control of sensor activity. The development of wireless sensor networks was motivated by military applications such as battlefield surveillance; today such networks are used in many industrial and consumer applications, such as industrial process monitoring and control, machine health monitoring, and so on.

The WSN is built of "nodes" – from a few to several hundreds or even thousands, where each node is connected to one (or sometimes several) sensors. Each such sensor network node has typically several parts: a radio transceiver with an internal antenna or connection to an external antenna, a microcontroller, an electronic circuit for interfacing with the sensors and an energy source, usually a battery or an embedded form of energy harvesting. A sensor node might vary in size from that of a shoebox down to the size of a grain of dust, although functioning "motes" of genuine microscopic dimensions have yet to be created. The cost of sensor nodes is similarly variable, ranging from a few to hundreds of dollars, depending on the complexity of the individual sensor nodes. Size and cost constraints on sensor nodes result in corresponding constraints on resources such as energy, memory, computational speed and communications bandwidth. The topology of the WSNs can vary from a simple star network to an advanced multi-hop wireless mesh network. The propagation technique between the hops of the network can be routing or flooding.

In computer science and telecommunications, wireless sensor networks are an active research area with numerous workshops and conferences arranged each year.

TYPES OF WSN:

•          Environmental

•          Medical

•          Military

•          Urban

–         Civic

–         Industrial

–         Residential

 

SYSTEM  BLOCK  DIAGRAM:

APPLICATION MESSAGING:

 

BLOCK  DIAGRAM – MOTE: 

 

WiseDB:

v  Written in C++

–         Utilizes open-source APIs

–         Application Programming Interfaces (API)

–         MySQL++ database API

–         Serial API

v  Relays information from mote network to database

v  Sends commands to mote network

Web program:

-Written in PHP4

-Utilizes Charting Software:
ChartDirector v3.0

-Retrieves Data for Specific Mote or All Motes

Data Retrieval  form:

 

Generated graph:

 

TinyOS(operating system):

Real-time operating system for          microcontrollers

•               Key Features:

–      Developed for sensing applications

–      Emphasis on low-power: Idle & sleep modes

–      Highly modular architecture

–      Efficient utilization of resources

•               Currently developed for Atmega microcontrollers