What are Wireless Sensor Networks (WSN)? Architecture and its Applications


Wireless Sensor Network (WSN)

Wireless Sensor Networks (WSN) can be defined as a network of wireless devices that can gather and communicate information through wireless links. The gathered information will be sent to the base station or sink for further processing.

WSN can generally be described as a network of nodes that cooperatively sense and control the environment, enabling interaction between persons or computers and the surrounding environment.

WSN consists of a distributed number of sensors that cooperatively monitor chemical (e.g. Dissolved Oxygen, pH, Small organic compounds, and large organic compounds), biological (e.g. microorganisms), and physical or environmental conditions such as temperature, pressure, sound, motion, and vibration at a location.

WSNs nowadays usually include;

  1. Sensor nodes
  2. Actuator nodes
  3. Gateways and clients (sink)


What is Sensor?

A sensor is a device that is capable of detecting changes. The sensor is a transducer, that measures physical phenomena e.g. heat, light, motion, vibration, and sound.

The sensor nodes could be equipped with various types of sensors, such as thermal, acoustic, chemical, pressure, weather, and optical sensors.

As various sensors are used, they can be utilized for building up many types of powerful applications. Each sensor has its characteristics and requirements.


Things to consider when designing Wireless Sensor Network (WSN)

  1. Data Aggregation

Data aggregation is the process of collecting and gathering information.

  1. Data Reliability

Data reliability defines the accuracy and completeness of the data.

  1. Localization

Localization is the process of identifying the current location of the node in a wireless sensor network (WSN).

  1. Node clustering

Node clustering is the process of grouping the node into various clusters.

  1. Energy-aware routing

It is an efficient technique used in wireless networks for routing the data from the source to the destination. And it is the process of utilizing minimum energy to transmit data between source and destination.

  1. Events scheduling

It is the scheduling process of executing at a particular time.

  1. Fault detection and security

It is the process of identifying the fault and solving it as well as enhancing the security of a wireless network.


What is a sensor network?

A sensor network consists of several sensor nodes (motes). Nodes are deployed either inside or near a parameter being sensed.

A sensor node is a basic unit of the sensor network, containing;

  1. Sensor
  2. Memory (data acquisition, communicating with sensors, processing, etc.)
  3. Transceiver (connection to the outer world, e.g. Sensor node and data acquisition)
  4. Power supply (battery).


WSNs  Architecture

Architecture refers to the physical arrangement of different sensor nodes (motes) in a wireless sensor network.

There are two common WSN architectures;

  1. Flat architecture
  2. Hierarchical architecture.


Flat architecture

In flat architecture, all nodes are treated equally. When a node needs to send data, it may find a route consisting of several hops to the sink.

Hierarchical architecture

In hierarchical routing protocols, clusters are created and a head node is assigned to each cluster. These nodes as the leaders of their groups have some responsibilities like collecting and aggregating the data from their respective clusters and transmitting the aggregated data to the BS.


Standards of Wireless Sensor Networks (WSN) 

Examples of standards of wireless sensor networks are;

  1. IEEE 802.15.4
  2. ZigBee
  3. 6LoWPAN (IPv6 over low power WPAN)


Applications of Wireless Sensor Networks (WSN)

  1. Intelligent buildings (or bridges);  monitor mechanical stress after earthquakes
  2. Smart agriculture; using a combination of sensors such as humidity, temperature, and pH to detect the risk of frost, and possible plant diseases.
  3. Smart cities; Noise pollution, garbage level, traffic, and parking level
  4. Industrial control;  fault detection
  5. Body area networks for sports and healthcare; Insulin pumps, Foot drop implants


Wireless Sensor Network (WSN) Topologies

The following are the topologies of wireless sensor networks;

  1. Star
  2. Tree
  3. Mesh


Disadvantages of WSN

  1. Limited storage capacity
  2. Limited processing power
  3. Works in short communication range
  4. Energy consumption is high
  5. Batteries with a limited lifetime.


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