This article will learn about Wireless Sensor Networks, the need to develop WSN, Applications, and their Topologies. However, before getting into the topic, let us brush up on some basic information about the sensor.
A sensor is an appliance that detects changes in physical or electrical, or other quantities. It produces an electrical or optical signal output as an acknowledgement of the change in that specific quantity. Also, it sends the obtained output as feedback to the microprocessor or microcontroller. For proper working of sensors, Power supply and grounding should be provided. The sensors, computing units, and communication elements form the sensor networks.
The events can be related to the physical world, an industrial environment, a biological system or an Information technology framework. The controlling or observing body can be a consumer application, government, civil, military, or industrial entity.
What are Wireless Sensor Networks?
As mentioned earlier, a typical sensor network consists of sensors, a controller and a communication system. A Wireless protocol is used in WSNs in the place of a communication system in a Sensor network.
Recent developments in MEMS Sensors (Micro Electro Mechanical System) and Wireless Communication has enabled cheap, low power, tiny and smart sensors, which can be deployed in a wide area and can be interconnected through wireless links and the internet for various civilian and military applications.
A Wireless Sensor Network consists of Sensor Nodes that are deployed in high density and often in large quantities. These WNS support sensing, data processing, embedded computing and connectivity.
Need for Wireless Sensor Networks
The recent developments in engineering, communication and networking have led to new sensor designs, information technologies and wireless systems. Such advanced sensors can be used as a bridge between the physical world with the digital world.
Sensors are used in numerous devices, industries, machines and the environment and help in avoiding infrastructure failures, accidents, conserving natural resources, preserving wildlife, increase productivity, provide security.
The use of distributed sensor network or system has also been contributed by the technological advances in VLSI, MEMS and Wireless Communication.
Therefore, With the help of modern semiconductor technology, you can develop more powerful microprocessors that are significantly smaller in size when compared to the previous generation products. This miniaturization of processing, computing and sensing technologies has led to tiny, low-power and cheap sensors, controllers and actuators.
Components of WSN
wireless sensor network can be divided into two elements. They are,
- Sensor Node
- Network Architecture
Sensor Node
A Sensor Node in a WSN consists of four basic components. They are:
- Power Supply
- Sensor
- Processing Unit
- Communication System
The sensor collects the analogue data from the physical world and an ADC converts this data to digital data. The main processing unit, which is usually a microprocessor or a microcontroller, performs intelligent data processing and manipulation.
A communication system consists of a radio system, usually a short-range radio, for data transmission and reception. As all the components are low-power devices, a small battery like CR-2032, is used to power the entire system.
Despite the name, a Sensor Node consists of not only the sensing component but also other important features like processing, communication and storage units.
Finally, all these features, components and enhancements make a Sensor Node responsible for physical world data collection, network analysis, data correlation and fusion of data from another sensor with its own data.
Network Architecture
When a large number of sensor nodes are deployed in a large area to co-operatively monitor a physical environment, the networking of this sensor node is equally important.
A sensor node in a WSN not only communicates with other sensor nodes but also with a Base Station (BS) using wireless communication.
The base station sends commands to the sensor nodes and the sensor node perform the task by collaborating with each other. After collecting the necessary data, the sensor nodes send the data back to the base station.
A base station also acts as a gateway to other networks through the internet. After receiving the data from the sensor nodes, a base station performs simple data processing and sends the updated information to the user using the internet.
When each sensor node is connected to the base station is known as Single-hop network architecture. Although long-distance transmission is possible, the energy consumption for communication will be significantly higher than data collection and computation.
Hence, Multi-hop network architecture is usually used. Instead of one single link between the sensor node and the base station, the data is transmitted through one or more intermediate node.
Flat network architecture and Hierarchical network architecture were the 2 two ways to implement it. In flat architecture, the base station sends commands to all the sensor nodes but the sensor node with matching query will respond using its peer nodes via a multi-hop path.
Hierarchical architecture is a group of sensor nodes that are formed as a cluster and the sensor nodes transmit data to corresponding cluster heads. The cluster heads can then relay the data to the base station.
Network Topologies in WSN
We have already seen that a WSN can be either a single-hop network or a multi-hop network. They are,
Star Topology
In star topology, hub or switch is a single central node. In the network every node is connected to the hub. Star topology is very easy to implement, design and expand. As all the data flows through the hub, it plays an important role in the network and a failure in the hub can result in failure of entire network.
Tree Topology
A single root node at the top is connected to many nodes in the next level and this continues. The processing power and energy consumption is highest at the root node and keeps on decreasing as we go down the hierarchical order.
Mesh Topology
In a mesh topology, apart from transmitting its own data, each node also acts as a relay for transmitting data of other connected nodes. Fully Connected Mesh and Partially Connected Mesh were the two types of mesh topology.
Therefore, each node is connected to every other node in fully connected mesh topology. In partially connected mesh topology, a node is connected one or more neighboring nodes.
Applications of Wireless Sensor Networks
Theoretically speaking, the possible applications of Wireless Sensor Networks are unlimited some are,
- Air Traffic Control (ATC)
- Heating Ventilation and Air Conditioning (HVAC)
- Industrial Assembly Line
- Automotive Sensors
- Battlefield Management and Surveillance
- Biomedical Applications
- Bridge and Highway Monitoring
- Disaster Management
- Earthquake Detection
- Electricity Load Management
- Environment Control and Monitoring
- Industrial Automation
- Inventory Management
- Personal Health Care
- Security Systems
- Tsunami Alert Systems
- Weather Sensing and Monitoring
Conclusion
In conclusion, Wireless Sensor Network technology has an incredible potential to enhance quality of life in all aspects and is likely to be widely used in the medium-term future. Therefore, with this article we came to know about the basics, working and topologies of WSN.
