Sensor Networks : An Overview-2

Sensor network s are dense wireless networks of small, low-cost sensors, which collect and disseminate environmental data. Wireless sensor networks facilitate monitoring and controlling of physical environments from remote locations with better accuracy. In this paper, the authors provide an overview of overcoming various energy and computational constraints deficiencies through more energy efficient routing, localization algorithms, system design and the solutions proposed in recent research literature.

A sensor network can be described as a collection of sensor nodes which co-ordinate to perform some specific action. Unlike traditional networks, sensor networks depend on dense deployment and co-ordination to carry out their tasks.

Sensor networks have a variety of applications. fro examples include environmental monitoring, condition based maintenance, habitat monitoring, seismic detection, military surveillance, inventory tracking,etc.

Challenges :
In spite of the diverse applications, sensor networks pose a number of unique thechincal challenges :

  • Ad Hoc Deployment : Most sensor nodes are deployed in regions which have no network infrastructure at all.
  • Unattended operation : In most cases, once deployed, sensor networks have no human intervention.
  • Untethered : The sensor nodes are not connected to any anergy source. There is only a finite source of energy.
  • Dynamic changes : It is required that sensor network system can be adaptable to changing connectivity as well as changing environmental stimuli.

The authors survey a number of papers that propose solutions in these following areas :
– Energy efficiency
– Localization
– Routing

Energy Efficiency :
Energy consumption is the most factor to determine the life of a sensor network because usually sensor nodes are driven by battery and have very low energy resources. This makes energy optimization more complicated in sensor networks because it involved not only reduction of energy consumption but also prolonging the life of the network as much as possible.
The power consumed by the sensor nodes can be reduced by developing design methodologies and architectures which help in energy aware design of sensor networks.

A sensor node usually consists of four sub-systems :

  • a computing subsystem : It consist of a microprocessor (MCU)
  • a communication subsystem : It consists of a short range radio
  • a sensing subsystem : It consists of a group of sensors and actuators and link the node to the outside world.
  • a power supply subsystem : It consists of a battery which supplies power to the node.

Localization :
In sensor networks, nodes are deployed into a an unplanned infrastructure where there is no a priori knowledge of location. The problem of estimating spatial-coordinate of the node is referred to as localization. Some solution is use Global Positioning System (GPS), recursive trilateral/multilateral techniques, proximity based localization.

Routing :
Conventional routing protocols have several limitations when being used in sensor networks due to the energy constrained nature of these networks. These protocols essentially follow the flooding technique in which a node stores the data item it receives and then sends copies of the data item to all its neighbors. There are two main deficiencies to this approach :
– Resource management.
Some of the routing protocol which have been proposed for sensor networks aimed at eliminating these problems are :
– Negotiation based protocols – Sensor Protocols for Information via Negotiation (SPIN)
– Directed Diffusion
– Energy Aware Routing
– Rumor Routing
– Multipath routing
– Media Access Control in Sensor Networks

Simulators for Sensor Networks :
– NS-2
– GloMoSim
– SensorSim

Reference :
Archana Bharathidasan, Vijay Anand Sai Ponduru
University of California

Note : This resume is created for self-learning only. Author and Publisher hold copyrights

Paper Predator Jutsu [Mode On]

February 14 2008,
Taipei City
High Speed Network Lab

Udin Harun

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