IoT Communication Protocols—Network Protocols – Technical Articles

One of the main pillars of IoT is its connectivity. It consists of a huge network of elements, both objects and people of different sizes and shapes, which are connected to gather and share information. In general, the information is gathered and used to automate or help make decisions. Due to the variety of data types and applications, different communication and network protocols are needed.

In this article, we will review the main characteristics of some of the main IoT protocols, as well as some of their pros and cons.

IoT Communication Parameters

Before taking the leap and deploying an IoT solution, it is critical to know the limiting factors of each technology. Communication protocols are the set of rules established between nodes to exchange information in a reliable and safe manner.

Here are some of the main aspects of a communication protocol:

Speed or Data Rate: the amount of information to be transmitted within a time duration. It is usually expressed in bps (bits per second), kbps, Mbps, or Gbps. 

Range: the maximum distance between two intercommunicating nodes. It mainly depends upon the transmitting power, the frequency band used, and the type of modulation. It can be also affected by the meteorological conditions or the physical placement of the nodes. In Figure 1 you can see a rough graph of the data rate versus the range of various IoT network protocols.

Figure 1. Data rate vs. range of various IoT network protocols. Image used courtesy of Embien

Power Consumption: the amount of energy that a node needs to work within its lifetime. This parameter defines the need for permanent power or the use of a battery. Since there are many applications using batteries, thus power consumption is a critical parameter. This means it will affect other elements such as the number of sensors or the communication power transmission. Furthermore, since batteries have a limited lifetime, the power consumption can have a direct impact on the maintenance strategy.

Interoperability: the capability to exchange information between nodes, even if they are of different types.

Scalability: the challenge of deploying a higher number of nodes, increasing the number of end-users, as well as the amount of data to store and process without the need of migrating the technology.

Cost: the price of installing and maintaining a specific technology. Power consumption, maintenance, and scalability have a big impact on the network cost.

Network Topology: the way nodes communicate with each other. Topologies can be the same as those used in traditional networks. Star, mesh, point-to-point, and point-to-multipoint are some examples of topologies, which can be seen in Figure 2.

Figure 2. Examples of different network topologies. Image used courtesy of ITPRC

Security: the way to protect data being sent and received. It is necessary to ensure that the communication transmitted between nodes arrives only at the intended nodes. The IoT technologies are already ubiquitous and they can communicate sensitive information to the users; thus, the communication needs to be protected against third parties. 

IoT Protocol Basics

Protocols allow nodes to have a structured way to interact between them. Since the needs and use cases of IoT devices have quickly evolved over the last few years, so have the protocols. All in all, there are mainly two types of protocols: network and data. This classification comes from the OSI (open systems interconnection) model, widely used in IT communication networks.

Below you can get a general understanding of the main IoT network protocols.

Bluetooth: This protocol works within the frequency of 2.4 GHz, and can be used for short-range (<100 m) applications. One step further into Its evolution is Bluetooth Low Energy (BLE), which presents a significant reduction in the power needed for this protocol. This type can be beneficial for the transmission of small amounts of data from sensors or wearables. An example node network layout can be seen in Figure 3.

Figure 3. An example of Bluetooth IoT network nodes in a smart home. 

Cellular: Current cellular infrastructure can be also used to extend the communication capabilities of IoT nodes. Depending upon the chosen band and the specific technology, it can be adequate for low power applications (e.g., 2G) as well as for high data rates applications (e.g., LTE). Additionally, there are subtypes of cellular communications, such as the LTE-M and NB-IoT, which were born to provide more data bandwidth or lower power use, respectively.

LoRaWAN: it is a low-power, wide-area (LPWA) protocol designed for battery-powered systems. It operates in the sub GHz 433/868/915 MHz and within the 2.4 GHz. LoRaWAN networks generally follow star topologies, where the elements are: end nodes, gateways, and a set of servers. The OSI reference model can be seen in Figure 4.

Figure 4. The OSI reference model for LoRa and LoRaWan. 

Near field communications (NFC): NFC works in the frequency band of 13.56 MHz and the range is a few centimeters. This type of communication is used to extend close-contact communications. In NFC there is an active node (such as a smartphone) generating an RF field that energizes a tag. It works in the frequency band of 13.56 MHz and the range is a few centimeters.

Sigfox: Sigfox uses a technology-based ultra-narrow band (UNB) and it works in the ISM bands, requiring a dedicated infrastructure. It means that it can be globally used but a local operator is needed.

Wi-FI: Working in the frequency of 2.4 GHz and 5 GHz, Wi-Fi connectivity is widely chosen because of its pervasiveness and high data rates. Its main drawback is its high power consumption, so it is not frequently used in battery-powered applications.

Wi-Sun: Wi-Sun is a field area network (FAN) protocol created by the Wi-Sun Alliance and designed to have a low power consumption and latency. It operates in the sub GHz frequency bands as well as in the 2.4 GHz band through a mesh topology.

ZigBee: This communication protocol works in the 2.4 GHz band, for short-range (<100 m) in restricted areas. ZigBee is made for transmitting small amounts of information, namely where really low latency is needed and is widely used in the industry and consumer applications. The ZigBee RF4CE was made to replace IR remote controls (e.g., TVs and DVD systems) and remove the need of having a line of sight between the remote control and the device.

Z-wave: intended for home automation applications (Figure 5), working in ISM frequency bands and with a rate up to 100 Kbps. Its applications follow a mesh network topology performing up to 4 hopes.

Figure 5. An example application of a Z-Wave IoT network at home. Image used courtesy of Qubino

The following table (Table 1) shows the main characteristics of the listed communication protocols, ordered by range:

Table 1. Communication protocol characteristics