Wireless sensor network (WSN)

• A wireless sensor network (WSN) is one form of system or setup in which multiple sensor nodes are interconnected with each other through a wireless communication medium.
• Each sensor node is a tiny energy-bounded, multifunctional device that collects data from its nearby environment then performs some sort of computation on collected data.
• Then send all this gathered data towards the main base station or sink.

Category 1 WSNs (C1WSNs)

• These are invariably mesh-based systems with multihop radio connectivity among or between WSNs.
• It utilizes dynamic routing in both the wireless and wireline portions of the network.
• C1WSNs are networks in which end devices like sensors are permitted to be more than one radio hop away from a routing or forwarding node.
• The forwarding node is a wireless router that supports dynamic routing.
• Wireless routers are often connected over wireless links.

Features of C1WSNs:

• Sensor nodes can support communications on behalf of other sensor nodes by acting as repeaters.
• The forwarding node supports dynamic routing and more than one physical link to the rest of the network is physically and logically present.
• The radio links are measured in thousands of meters.
• The forwarding node can support data processing or reduction on behalf of the sensor nodes.
• These all features made it a relatively Complex and meshy wireless system.
• An example of this type of network is Military theater systems.

Category 2 WSNs (C2WSNs)

• These are point-to-point or multipoint-to-point star-based systems generally with single-hop radio connectivity to WSNs.
• It utilizes static routing over the wireless sensor network.
• Typically, there will be only one route from the WSNs to the companion terrestrial/wireline forwarding node.
• C2WSNs are networks in which end devices like sensors are one radio hop away from a terrestrially homed forwarding node.
• The forwarding node calls it a wireless router that is connected to the terrestrial network via either a landline or a point-to-point wireless link.

Features of C2WSNs:

• Sensor nodes do not support communications on behalf of any other sensor nodes.
• The forwarding node supports only static routing to the terrestrial network, and only one physical link to the terrestrial network is present.
• The radio link is measured in hundreds of meters.
• The forwarding node does not support data processing or reduction on behalf of the sensor nodes.
• These all features made it a relatively simple wireless system.
• An example of this type of network is Residential control systems.