IoT Network Topologies

IoT networks are structured networks in which nodes are organised according to a defined hierarchy. An IoT network topology is a given arrangement or configuration of IoT devices to form an IoT network. IoT network topology refers to the structural layout of devices (nodes) in an IoT network, shaping how devices communicate and how data flows between them. The choice of topology significantly impacts the network’s performance, reliability, scalability, and cost. Below is an expanded discussion of fundamental IoT network topologies, their attributes, advantages, challenges, and use cases.

1. Star Topology

Star Topology
Figure 1: Star Topology

In a star topology (figure 1), all devices are connected directly to a central hub or gateway, the network’s communication and coordination point. The nodes are within the radio propagation of the gateway. Thus, they can communicate directly with the gateway, but if a node is out of the propagation or coverage range of the gateway, it is cut off from the network.

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2. Tree Topology

Tree Topology
Figure 2: Tree Topology

Tree topology (figure 2) organises devices hierarchically, with a root node at the top and subsequent devices forming branches at multiple levels. It is a structured extension of the star topology. In this type of topology, some nodes operate as relays for others. If one of the relays fails (crashes or experiences poor link quality), all the descendant nodes that depend on it will be disconnected from the network.
There is a particular case of the tree-of-trees topology available (among others in Bluetooth) called Scatternet.

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3. Mesh Topology

Mesh Topology
Figure 3: Mesh Topology

In a mesh topology (figure 3), each device is interconnected with one or more devices, creating multiple communication paths. Mesh networks can be partial (some nodes connected) or full (all nodes interconnected). It extends the tree topology by adding redundant paths. Each node in the network has at least two neighbours to which the packet can be transmitted. Therefore, if some nodes fail, the multi-hop networks or the traffic flow will not be interrupted.

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4. Linear Topologies

Linear Topology
Figure 4: Linear Topology

Linear topology (figure 4) connects devices sequentially, with each node linked to its immediate neighbour.

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5. Bus Topology

Bus Topology
Figure 5: Bus Topology

In a bus topology (figure 5), all devices share a common communication backbone, and data is broadcast across the bus.

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6. Ring Topology

Ring Topology
Figure 6: Ring Topology

Ring topology (figure 6) arranges devices in a closed loop, where data travels around the ring in one or both directions.

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7. Hybrid Topology

Hybrid Topology
Figure 7: Hybrid Topology

Hybrid topology (figure 7) combines elements of multiple topologies to create a customised network that leverages their strengths and minimises weaknesses.

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Choosing the proper IoT network topology requires carefully evaluating the application’s needs, including reliability, scalability, cost, and energy efficiency. Often, IoT deployments use a combination of topologies to optimise performance across diverse requirements. Understanding each topology’s strengths and limitations is essential for designing effective IoT networks.