The main characteristics, advantages and disadvantages of IoT protocols

One of the main pillars of IoT is its connectivity. It consists of a huge network of elements, including objects and people of different sizes and shapes, which are connected to collect and share information. Usually, information is collected and used for automation or to help make decisions. Due to the diversity of data types and applications, different communication and network protocols are required.

In this article, we’ll review the key features of some of the main IoT protocols, as well as some of their pros and cons.

IoT communication parameters

Before making the leap and deploying an IoT solution, it is critical to understand the limitations of each technology. A communication protocol is a set of rules established between nodes to exchange information in a reliable and secure manner.

Following are some key aspects of the communication protocol:

Speed ​​or Data Rate: The amount of information to be transferred in a period of time. It is usually expressed in bps (bits per second), kbps, Mbps, or Gbps.

Range: The maximum distance between two nodes that can communicate with each other. It depends primarily on the transmit power, the frequency band used, and the type of modulation. It can also be affected by meteorological conditions or the physical location of the nodes. In Figure 1, you can see a rough graph of data rate vs. range for various IoT network protocols.

Figure 1. Data rates and ranges of various IoT network protocols. Image courtesy of Enbien

Power consumption: the energy required by a node to work during its lifetime. This parameter defines the need for a permanent power supply or the use of batteries. Since there are many applications that use batteries, power consumption is a key parameter. This means that it will affect other elements such as the number of sensors or communication power transmission. In addition, since batteries have a limited service life, power consumption has a direct impact on maintenance strategies.

Interoperability: The ability of nodes to exchange information even if they are of different types.

Scalability: The challenge of deploying more nodes, increasing the number of end users, and the amount of data that can be stored and processed without migrating technology.

Cost: The price of installing and maintaining a specific technology. Power consumption, maintenance, and scalability have a large impact on network costs.

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

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

Security: Protecting the way data is sent and received. It must be ensured that the communications transmitted between nodes only reach the intended nodes. IoT technologies have become ubiquitous and they can convey sensitive information to users; therefore, the communications need to be protected from third parties.

IoT Protocol Basics

Protocols allow nodes to interact between them in a structured way. As the requirements and use cases of IoT devices have evolved rapidly over the past few years, so have the protocols. In summary, there are two main types of protocols: network and data. This classification comes from the OSI (Open Systems Interconnection) model that is widely used in IT communication networks.

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

Bluetooth: This protocol operates in the 2.4 GHz frequency range and can be used for short-range (<100 m) applications. Bluetooth Low Energy (BLE) is a further step in its development, which significantly reduces the power required by this protocol. This type is good for transmitting small amounts of data from sensors or wearable devices. An example node network layout can be seen in Figure 3.

Figure 3. Example of a Bluetooth IoT network node in a smart home.

Cellular: Current cellular infrastructure can also be used to extend the communication capabilities of IoT nodes. Depending on the frequency band and specific technology chosen, it can be suitable for low-power applications (e.g., 2G) as well as high data rate applications (e.g., LTE). In addition, there are some cellular communication subtypes, such as LTE-M and NB-IoT, which are born to provide more data bandwidth or lower power consumption respectively.

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

Figure 4. OSI reference model for LoRa and LoRaWan.

Near Field Communication (NFC): NFC operates in the 13.56 MHz frequency band and has a range of a few centimeters. This type of communication is used to extend close contact communication. In NFC, there is an active node (such as a smartphone) that generates a radio frequency field that provides energy to the tag. It operates in the 13.56 MHz frequency band and has a range of a few centimeters.

Sigfox: Sigfox uses Ultra Narrow Band (UNB) based technology, which works in the ISM band and requires dedicated infrastructure. This means it can be used worldwide but requires a local operator.

Wi-Fi: Operating at 2.4 GHz and 5 GHz frequencies, Wi-Fi connectivity is widely chosen for its ubiquity and high data rates. Its main drawback is its high power consumption, so it is not often used in battery-powered applications.

Wi-Sun: Wi-Sun is a Field Area Network (FAN) protocol created by the Wi-Sun Alliance, designed for low power consumption and low latency. It operates in the sub GHz band and the 2.4 GHz band via a mesh topology.

ZigBee: This communication protocol operates in the 2.4 GHz frequency band and is suitable for short distances (<100 m) in confined areas. ZigBee is used to transmit small amounts of information, i.e. where really low latency is required, and is widely used in industry and consumer applications. ZigBee RF4CE is designed to replace infrared remote controls (e.g. for TVs and DVD systems) and does not require line of sight between the remote control and the device.

Z-wave: Suitable for home automation applications (Figure 5), it operates in the ISM band with a rate of up to 100 Kbps. Its application follows a mesh network topology and implements a maximum of 4 wishes.

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