Communication technologies and protocols

Data flows through a number of different devices during the back-and-forth between IoT nodes and cloud applications. These devices implement various communication technologies and protocols and the following diagram shows the most common choices:

Figure 1.4 – Communication technologies and protocols

In relation to the four main communication paths in the whole chain, the main distinction is related to the wireless or wired nature of the communication.

As per the preceding figure, the field-to-device path is usually wired: sensors, actuators, and devices connect to an IoT node thanks to wires. They pack and exchange data according to one of the standards for wired interfaces shown in the figure.

The device-to-gateway path can be wired or wireless depending on the technical requirement of the node for each specific application. Wireless IoT nodes offer the following benefits compared to wired IoT nodes:

• Mobility: Wireless IoT nodes are not restricted by physical connections and can be easily moved or relocated, providing more flexibility and freedom
• Ease of installation: Wireless nodes do not require cabling and can be installed much faster and more easily, reducing installation costs and time
• Scalability: Adding new nodes or devices to a wireless IoT network is easier and less expensive than adding wired nodes
• No infrastructure requirements: Wireless IoT nodes do not require a pre-existing wired infrastructure, making them ideal for remote or hard-to-reach locations
• Improved reliability: Wireless nodes are less susceptible to failure caused by physical damage to cables, making them more reliable for many IoT applications

However, it’s worth mentioning that wireless IoT nodes may suffer from interference from other wireless devices, limited range, and potential security issues, so it’s important to consider these limitations when choosing between wired and wireless IoT nodes.

For example, the IoT nodes for the load, vibrations, and structural monitoring of a bridge over a river, which respectively provide useful information about the maintenance, traffic balance, and improvement requirements, don’t need to be wireless. Many smart agriculture applications, on the other hand, benefit from long-range wireless technologies because of the difficulties and the installation costs of a wired network covering huge areas.

Considering the Kids park has a lot of IoT nodes, we can roughly divide the applications in the different market verticals into four main groups:

• Consumer devices with a very short transmission range: Wearables, safety devices, remote controls, and toys that typically use a Bluetooth or a Bluetooth Low Energy (BLE) connection to a mobile phone that shares the connectivity to the internet. This approach demonstrates the possibility of daisy-chaining multiple gateways with different technologies to reach the required connectivity.
• Consumer devices with a short transmission range: This is the case for home automation devices, such as the thermostat of your house or appliances, entertainment devices, personal instruments, and healthcare devices connected to the internet through a cabled Wi-Fi access point.
• Wireless professional devices: Automotive, smart agriculture, mining, and some logistics and outdoor industrial applications require very long-distance transmission ranges provided by the latest cellular technologies, which includes 3G/4G/5G or LPWAN.
• Wired professional devices: Some infrastructural projects, such as the monitoring of bridges and dams or indoor industrial projects, require wired nodes to increase reliability, increase the data throughput of the transmission, reduce the maintenance required for battery replacement, and increase data security.

The gateway-to-cloud link is wired in most IoT applications and, eventually, the gateway provides a backhaul wireless connectivity to the internet. This is the case of professional Wi-Fi and LoRa gateways that implement an Ethernet interface and also a cellular modem: the gateway automatically swaps to cellular if the Ethernet connection fails.

Defining the nature of the cloud-to-cloud communication path is a little bit trickier because we need to consider that cloud apps run on cloud platforms, and these are composed of servers interconnected to each other. The physical connection among the servers is definitely wired, but we may consider the logical connection between cloud applications wireless because, when compared to applications installed on a single server on the internet, wireless and wired IoT nodes offer the same benefits.

Figure 1.5 – Wired/wireless communication technologies

In this section, we discussed the high-level architecture of an end-to-end IoT application with multiple nodes, gateways, and the cloud. In the second part of the section, we discussed communication technologies and protocols, where we divided different communication technologies into wireless and wired mediums for better understanding. In the next section, we will discuss the security of IoT solutions, as well as device provisioning services, in detail.