A Point-to-Point Topology
All wireless network technologies support a point-to-point topology.
In a point-to-point network there are two nodes which communicate directly with each other. It is the simplest form of a wireless network and is often used for simple remote monitoring applications. Wireless point-to-point networks can be useful in hazardous environments where running wires is difficult or dangerous and it is a cost-effective alternative to installing cables between two buildings.
Advantages of a point-to-point network:
- Simple to deploy.
- Low cost.
Disadvantages of a point-to-point network:
- The network cannot scale beyond its two nodes, therefore the range of network is limited to one hop.
- The failure of any one node can be disastrous.
A Star Topology
Most wireless network technologies support a star (point-to-multipoint) topology.
A star network is one of the most common networks. It consists of one gateway node to which all other nodes connect. Nodes can only communicate with each other via the gateway. Repeaters can be used to fill gaps in the coverage.
Advantages of a Star Network:
- The network performance is fast and reliable.
- Faulty nodes / devices can be identified and isolated swiftly.
Disadvantages of a Star Network:
- Range is limited to the transmission range of a single device.
- If the gateway node fails the whole network goes down.
A Mesh Topology - Full / Partial Mesh
ZigBee, LoRa, IQRF, 6LoWPAN and Bluetooth 4.0 technologies for example can support mesh networks.
A mesh network consists of a gateway node, simple sensor nodes and sensor / router nodes. All network nodes can connect directly to each of the others in a full mesh topology. In a partial mesh topology, some nodes are connected to some of the others, but others are only connected to those with which they exchange the most data.
Advantages of a Mesh Network:
• Simultaneous up / downstream communication can support high traffic.
• Expansions and modifications can occur without disruption to other nodes.
• Self-healing - the network finds the fastest and most reliable paths to send data if nodes are blocked or lose their signal.
Disadvantages of a Mesh Network:
• High chances of redundancy in many of the network connections.
• Higher network latency due to multiple hops from the sensor to the gateway.
• Overall costs are higher and more labour intensive set - up and maintenance compared to other topologies.
Low Power Wide Area Networks (LPWANs)
LPWANs are often used when other wireless networks just aren’t quite good enough!
LPWAN technology suits applications where small packets of data need to be sent over long distances with a low power consumption, minimising cost and call out. As LPWANs can support more nodes over a larger coverage area, they are suited to industrial M2M / IoT applications.
Bluetooth, BLE, Wi-Fi and ZigBee are often not suited for long - range performance. Cellular networks are typically more power hungry and often not very cost effective.
The use of sub – 1 GHz frequencies in LPWANs achieves a better penetration into buildings or underground installations. Two major benefits of lower frequencies are less interference and an increased sensitivity translating directly to more efficient power usage. Long - range connectivity allows direct access to devices in the field. The base station typically serves a large number of devices thus greatly reducing costs.