In today’s digital world, machine-to-machine (M2M) is quickly becoming standard. M2M includes any technology that enables networked devices to exchange data or information. It can be wired or wireless, but the Internet of things (IoT) has made such wireless communication between devices commonplace.
The interconnected of things has also made these devices intelligent. Consider how much wearables, mobile devices, and consumer electronics can track, find, recall, and inform you — or one another. Now, artificial intelligence and machine learning are making these interactions smarter, quicker, and more meaningful.
Finding a connection
Where once computers were connected to the Internet through standard protocols, like TCP/IP and UDP, the IoT has no one standard protocol. Today’s IoT-connected devices are no longer only general-purpose computers, but also specialized devices built for predefined operations. Embedded and mobile devices vary in their computing features and applications.
Currently, there is no one protocol enabling IoT or M2M communication. Many protocols used are based on the applications and operations. Ideally, they should be quick, reliable, and efficient, regardless of the range.
In general, most IoT devices require low power, a short range, and connect wirelessly. They connect to a gateway, hub, or directly to the internet via a wireless interface.
Many of these devices are battery-powered and need to conserve energy to operate over long durations. They rarely, if ever, communicate heavy payloads with big headers or footers like conventional computers because they have limited resources.
In this article, we’ll cover the top M2M protocols currently in use this year.
M2M versus the IoT
The global machine-to-machine industry was worth U.S. $200 billion in size in 2022. There were about 12.5 billion M2M connections, which are expected to double to 25.2 billion by 2025.
In terms of the Internet of things, there are nearly 15.14 billion IoT devices active so far this year. That number is expected to double to 29.42 billion by 2030.
M2M and IoT are often used interchangeably, but they’re not exactly the same. The IoT requires M2M, but M2M is not dependent on the IoT.
M2M can be a point-point hardware-based communication between any two machines through wired or wireless interface. M2M devices can be isolated devices operating within a closed system. They often communicate only structured data in a unidirectional fashion through non-IP protocols.
The IoT is typically a software-based communication tool for exchanging sensor data over the Internet. IoT devices are usually connected via the Internet through a hub or gateway. The sensor data communicated in IoT can be structured or unstructured, depending on the application.
Almost all IoT devices are low-power wireless devices communicating data over IP protocols. Where M2M renders vertical applications in a closed system, the IoT serves horizontal applications involving multiple and/or multi-level applications.
Despite these differences, IoT devices are built over M2M systems by enabling them to connect and communicate with enterprise networks and a range of cloud services.
Popular M2M protocols
M2M devices can connect and communicate with one another through wired and wireless protocols — but most are wireless. Since the IoT has gained significant traction in the last decade, most M2M systems are the Internet of things.
In fact, almost 60% of all M2M connections are IoT devices. This is expected to increase to 90% by 2025. The top M2M protocols by 2023 are as follows.
WiFi is the most popular M2M protocol, accounting for about 55% of all M2M connections. WiFi serves as a reliable, encrypted, password-protected interface, which is widely available without additional infrastructure. M2M devices can easily connect and operate with a WiFi network to exchange data.
WiFi 6 or 802.11ax is the latest version of the protocol. WiFi 6 provides data speeds up to 9.6 Gbps, which is twice the previous version (WiFi 5.0). In addition to 2.4 GHz and 5 GHz bands, WiFi 6 provides an additional 6 GHz band that has a key role in leveraging data speeds.
New features have been added to WiFi 6, like OFDMA (Orthogonal Frequency Division Multiple Access), to improve the efficiency of the technology and beamforming to improve its reliability and range.
There are some drawbacks to WiFi technology, however. Setting up high-speed networks is relatively costly. Security can also be an issue, requiring password protection and software updates. More robust measures are necessary to ensure security against hacking and cyber-attacks.
WiFi signals can also be easily interrupted by other electronic devices and sources, so the technology could benefit from mechanisms ensuring range, reliability, and security.
Bluetooth is a short-range wireless communication technology almost 20% of M2M connections rely on. It’s easy to use and pair devices, connecting wearables to smartphones, sensors to gateways or fogs, or smart home devices with one another.
Bluetooth only communicates small amounts of data at a time, but it offers a low power consumption that makes it suitable for battery operation and most IoT devices. Bluetooth connections are secure, and the data communicated is protected by strong encryption.
The latest version is Bluetooth 5.3. The latest protocol can transfer data at a rate of 2 Mbps over a range of up to 400 meters. It’s enabled to find directions through Bluetooth signals, which is useful for applications like asset tracking and indoor navigation.
The new protocol allows higher data-speed transfers with reduced power consumption for high-definition video streaming, file transfers, and broadcasting audio to multiple devices from a single one. Mesh networking, low-energy audio, and ultra-wideband technology are notable new features.
M2M connections often use Bluetooth for data sharing, audio, controlling HID devices, and communication between devices. A shorter overall range, security vulnerabilities, and low bandwidth are still some areas of concern regarding the technology.
Zigbee is a low-power, low-bandwidth wireless technology for about 15% of all M2M connections. It’s gained popularity due to its mesh topology, low cost and power consumption, and strong encryption, enabling it to replace WiFi and Bluetooth in many applications.
It’s commonly used for industrial asset tracking, smart homes, factory automation, healthcare monitoring, irrigation control, and crop monitoring.
The latest version is Zigbee 3.0, which was released in 2017. Zigbee 3.0 can transfer sensor data at a rate of 270 kbps up to a range of 100 meters. It offers Zigbee LightLink for lighting applications. The LightLink supports color control, light dimming, and multiple lights together.
Some challenges include latency, low data rates, signal interference from other electronic devices, and power management of devices.
MQTT is a scalable, publish-subscribe protocol for enabling IoT and M2M communication. It’s used by about 65% of M2M connections (mostly the IoT) for communicating sensor data, controlling binary devices, and receiving commands from a central server.
MQTT may not fit all applications as it lacks required features like message prioritization or QoS levels. The fairly simplistic protocol also has low data rates, bandwidth, and security vulnerabilities. Despite these drawbacks, MQTT is one of the top M2M protocols for communicating sensor data intermittently. This makes it ideal for IoT devices that spend much time in sleep mode and need to communicate sensor data in small chunks but quite frequently.
The latest version is MQTT 5.0, released in 2019. MQTT 5.0 supports messages up to 256 KB with enhanced security features like TLS 1.3 and DTLS 1.2. Notable features include topic alias, session resumption, and the last bill & testament. The top development is MQTT over WebSockets (MQTT-WS) which allows the transportation of MQTT messages over Web Sockets.
The protocol is continuously evolving, so it’s worth keeping updated. For example, there’s now MQTT over 5G, MQTT over LoRaWAN, and MQTT over Quantum Networks are expected to emerge soon.
5G is the most promising technology for M2M communication. Currently, only 1% uses 5G connectivity, and that’s expected to increase to 5% by 2025 and 25% by 2030.
5G will be a key technology enabling smart cities, industrial automation, connected cars, augmented reality, video streaming, and healthcare IoT.
Most communication technologies are either high-speed, low-bandwidth/range or low-speed, high-bandwidth/range. No current wireless technology operates at long-range, high-speed, and high bandwidth. 5G technology will change that. This next-generation cellular technology will have increased bandwidth facilitating high-speed Internet with almost no latency and enhanced security and capacity to handle data communication simultaneously with multiple connections.
The technology aims to support massive machine-type communication (mMTC) and ultra-reliable, low-latency communication (URLLC). mMTC will be used for smart metering, smart cities, and asset tracking. URLLC will be a key technology stack for remote surgery, healthcare IoT, and connected cars.
5G is going through standardization and initial deployment. The 3GPP (3rd Generation Partnership Project) is laying out standards for the technology. Some level of 5G network is already deployed in more than 100 countries.
Although 5G guarantees connectivity among multiple connections in a small network circle without latency, high cost, and high-power consumption are its drawbacks. 5G will be most suitable for high-density networks deployed at large scale. Still, it fails to solve the problems in horizontal scaling IoT networks (where high data rates are not required but a reliable long-range network covering widely scattered devices is necessary). For this, LoRaWAN is the solution.
LoRaWAN is a long-range, low-cost, bandwidth, and power communication technology based on the LoRa modulation technique — a spread spectrum modulation technique suitable for long-range communication with low power consumption.
LoRa is a highly secure, scalable, and reliable M2M communication technology that will be useful in connecting remotely deployed devices that exchange small-footprint data at high frequency. Most IoT devices are in this category.
LoRaWAN will enable smart metering, asset tracking, wildlife tracking, agricultural monitoring, environment monitoring, and intelligent traffic management. It connects a few devices and facilitates low bandwidth and high latency communication between remote (or global) devices.
The number of LoRaWAN devices is estimated to reach 100 million by 2023, and is currently at 20% worldwide for M2M connections. LoRaWAN 1.1 was released in 2021, and it’s packed with extended range, improved security, and support for IPv6.
In 2022, LoRaWAN for the Things Network was introduced, and, this year, LoRaWAN for smart cities and LoRaWAN for The Internet of Things have been launched.
Sigfox is a niche M2M communication technology catering to the same market as LPWAN. In 2016, Sigfox was used by nearly 25% of M2M connections. That’s dropped to only 5% this year. One reason is the growth of competitive LPWAN technologies, such as LoRaWAN.
Unfortunately, Sigfox is costly and has a low data throughput and limited range compared to current technologies. Whether it will survive the competition will depend on advancements by its parent company. But Sigfox is still used to some extent.
LTE-M is an M2M communication technology designed for a different scenario than 5G and LPWAN. LTE-M is a long-range, low-power, high-data throughput technology used globally. The technology aims to cater to devices deployed globally or over a long-range, but it requires an extensive footprint data exchange despite its low power consumption.
The technology is expensive, has several security vulnerabilities, and is highly complex in design — but it caters to a unique niche. The technology is well-suited for several applications in smart cities, as well as agricultural monitoring, asset tracking, and environment monitoring. LPWAN technologies face hurdles in such applications in terms of feasibility and deployment. So, LTE-M is an option
The latest standard is LTE-M Cat-M1, which was released in 2017 by 3GPP. In 2019, LTE-M Cat-NB1 was introduced, further reducing the power footprint and extending the range of LTE-M. In 2021, LTE-M for smart cities emerged, targeting applications like smart parking, water management, and air-quality monitoring. In 2022, LTE-M for the Internet of Things launched. We’ll see what’s next!
NB-IoT is a long-range, low-cost, low-power communication protocol that targets the same market as LoRaWAN. While LoRaWAN is based on Chirp spread spectrum, NB-IoT is based on orthogonal frequency-division multiplexing (OFDM).
Whereas LoRaWAN operates on an unlicensed spectrum, NB-IoT operates on a licensed range. It also has better reliability and coverage compared. LoRaWAN is preferred in cost-sensitive applications like smart farming, asset tracking, and environment monitoring, NB-IoT has an edge in applications like smart metering, industrial automation, and traffic management.
In 2021, the proportion of M2M connections using NB-IoT grew at 16% compared to 4% of use in 2016.
The latest standard is NB-IoT Cat-M1, released by 3GPP in 2017. In 2019, NB-IoT Cat-NB1 was introduced to improve range and reduce power consumption. In 2021, NB-IoT for smart cities was introduced, followed by NB-IoT for the Internet of Things in 2022.
AMQP (Advanced Message Queuing Protocol) and XMPP (Extensible Messaging and Presence Protocol) are other popular M2M communication protocols or technologies. But their use is decreasing to about 1% of M2M connections.
MQTT and CoAP are quickly replacing both of these standards. MQTT is used by 65% of M2M connections and CoAP is used by 6% of M2M connections worldwide.
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