Although machine to machine (M2M) communication and Internet of things (IOT) are related, they are two different concepts, but they are often used as synonyms. This leads to misunderstanding and even confusion about their respective characteristics, functions, design and implementation requirements.
This paper explains the differences between the two, illustrates the two technologies respectively, and compares the unique differences between M2M and the Internet of things system by taking the design solutions of multi tech systems, freewave technologies, Hirschmann and B + B smartworx as examples. In addition, this paper also introduces the new M2M functions such as wireless (OTA) update and multi-level security; These functions help to enhance the network function and reduce the access threshold. Finally, this paper guides designers to select the appropriate M2M traffic package to reduce the cost of data communication.
Differences between M2M and Internet of things
Although both M2M and IOT technologies involve data sharing and establishing data transmission links, they are still different: IOT is a device network connecting the Internet, while M2M refers to the automatic communication technology between two or more electronic systems (or machines and devices). Machines or equipment connected in M2M point-to-point or point to multipoint can be sensors, actuators, embedded systems or other connection elements.
It is important to note that M2M existed before the word "Internet of things" and even before the emergence of commercial Internet in the mid-1990s. M2M originated from the telemetry application in the early 20th century and appeared after the advent of two-way radio communication. However, the first digital cellular network GSM launched in the 1990s has prompted M2M communication to enter a new stage of development.
About a decade later, the Internet of things emerged and became the main connection tool through an open IP based network. Since then, the boundary between these two unique communication technologies has gradually become blurred. In order to clarify the difference between the two, the application mode of M2M and Internet of things model can be effectively explained with the help of example application (heart rate sensor in this paper).
If it is necessary to connect the sensor monitoring the patient's heart rate to an external device or medical server to enable doctors to understand the patient's health status, it can be realized through M2M application. On the contrary, if the heart rate sensor is integrated into the interactive devices around the patient and sends alarm information to the smartphone of the patient's attending doctor or family members, it belongs to the category of Internet of things.
M2M applications can adopt wired, wireless and cellular connection mechanisms, including automatic meter reading, intelligent connection of traffic lights, and home safety and assisted living based on surveillance cameras. It is with network technology that M2M communication began to integrate into relevant Internet of things design.
How does the Internet of things complement M2M
In a broad sense, M2M communication has entered a new stage after entering the era of Internet of things. As an associated technology of the Internet of things, the same rapidly developing Internet of things related connection technologies and solutions can be used by M2M, especially in wireless. For example, the mtc-h5-b01-us-eu-gb multiconnect cell 100 series cellular modem of multi tech systems supports both M2M and Internet of things applications (Figure 1).
Figure 1: mtc-h5-b01-us-eu-gb cellular modem (left) of multi tech systems, which is designed for M2M applications and can also be used for Internet of things services（ Image source: telit)
This cellular modem supports GSM, 4G networks (cat 4 and cat-m1) and can be used in M2M applications such as process automation, emergency services, remote patient monitoring, renewable energy systems, and system management of train tail devices.
Cell 100 series modems provide a variety of interface options, including RS-232 and USB serial interface, which can meet a wide range of application requirements. The hardware is supported by MultiTech connection manager; This software package can automatically detect USB and serial devices, download the required drivers, and ensure that the communication port is mapped correctly to establish M2M connection.
Suppliers use highly integrated connectivity to develop low-power Internet of things solutions, while also promoting the development of compact M2M radios to provide a variety of voltage inputs and network configurations.
The mm2 series 900 MHz RF module of freewave technologies is a typical example. The module can be used as an endpoint in point-to-point and point to multipoint network topologies. The RF front-end module integrates gallium arsenide (GaAs) FET and multistage surface acoustic wave (SAW) filtering to improve sensitivity and overload resistance. Optional data rate: 115.2 Kbps or 153.6 Kbps.
Typical specifications of the mm2 series: the output power is 1 W, the input sensitivity is - 108 DBM, and the RF range can reach 20 MI. This range defines a clear sight distance.
M2M security and reliability
Security and reliability should be paid attention to in the design of M2M and Internet of things, but these two points are more important because M2M applications usually do not involve human-computer interaction. In fact, security and reliability are key obstacles for widely covered M2M networks.
For wired applications, engineers can configure M2M network according to reliability requirements with the help of Hirschmann's rs20 / rs30 Industrial DIN rail Ethernet switch. The rs20 switch provides 4 to 25 Fast Ethernet ports to ensure extremely high fault tolerance (Figure 2). Similarly, the company's rs30 switch has 8 to 24 ports, including 2 Gigabit Ethernet ports and 8, 16 or 24 Fast Ethernet ports.
Figure 2: Hirschmann's rs20 Ethernet switch provides 4 to 25 Fast Ethernet ports to minimize failures（ Image source: Hirschmann)
Fast Ethernet port and Gigabit Ethernet port can be defined separately, so that M2M designers can select redundant protocol and security mechanism according to specific design requirements.
In M2M applications that focus on reliability, high network availability can be ensured in view of supporting standards such as media Redundancy Protocol (MRP) and multiple spanning tree protocol (MSTP). In addition, this industrial Ethernet switch also supports a variety of security mechanisms, including IP and MAC port security, SNMP V3, sshv2 and 802.1x multi client authentication.
For wireless applications, the airbornem2m Ethernet router and bridge of B + B smartworx provide single serial port and dual serial port models to improve the reliability of M2M applications (Figure 3). The dual serial port device of B + B smartworx can establish Wi Fi connection in 2.4 GHz and 5 GHz bands. Therefore, if the 2.4 GHz band is crowded due to too much wireless communication activity, the M2M router and bridge can switch to the 5 GHz band to keep the data transmission smooth.
Figure 3: schematic diagram of connecting M2M equipment through Ethernet or serial link with the help of highly secure Wi Fi bridge and router（ Image source: B + B smartworx)
In addition, the airbornem2m network equipment also integrates multi-level security methods: wireless security has passed 802.11i/wpa2 enterprise authentication; Network security is authenticated by extensible authentication protocol (EAP).
This M2M device provides secure shell protocol (SSH) public key authentication and fully encrypted data tunnel to improve network security. In addition, as far as the equipment is concerned, this M2M router and bridge has multi-level encryption function to protect the configuration data.
In M2M services using cellular connections, security and authentication are often incorporated into LTE standards. In terms of physical security, ESIM card is directly welded to the circuit board, so it is almost impossible to tamper with and remove the improper use of SIM card.
The SIM card in M2M application brings us to the last topic: M2M traffic package and related selection and use problems.
M2M traffic package
Since all major mobile operators have launched traffic packages and tariff packages for M2M services, M2M designers and users may have a lot of choices. However, some key criteria must be considered when evaluating various packages, such as the degree of customization of the application.
In addition, some affiliated operators specialize in providing M2M services, commonly referred to as mobile virtual network operators (MVNOs). These mobile operators provide remote M2M connection and management through wireless (OTA) services.
However, unlike the traditional SIM card used in mobile phones, the M2M SIM card provided by professional operators can provide users with traffic use control and other functions (such as activity monitoring and SIM card locking). In addition, with the tunnel network function, these SIM cards can be connected to specific application servers.
On the other hand, the packages of some professional M2M operators not only include traffic packages, but also provide other M2M devices such as modems and gateways, so as to easily build a complete M2M application. These M2M operators are often independent operators, and their network coverage depends on M2M application requirements.
For example, medical monitoring services may require only a single cellular network coverage, but truck transport fleets need a wider mobile network coverage. In addition, M2M users should ensure that the service provider has troubleshooting capability and can perform real-time remote troubleshooting.
Traffic package level
Finally, when it comes to the cost of M2M data transmission and the economy of traffic package, the nature of application is very important. For example, M2M applications such as wireless cash register (POS) and parking timer only transmit small packets occasionally, so pay per use is more reasonable than pay per device or fixed traffic package.
In addition, for M2M applications such as automatic meter reading, asset and vehicle tracking, and security alarm system, a small traffic package of 50 KB to 3 MB per month is sufficient. On the other hand, the traffic package in M2M (5 MB to 150 MB per month) is suitable for vending, retail and medical applications (Figure 4).
Figure 4: there is no so-called "one size fits all" M2M traffic package（ Image source: data2go wireless)
For applications such as digital signage, PLC for industrial monitoring and intelligent building management, large flow packages can be selected. Traffic ranges from 300 MB to 4 GB and is commonly used for M2M devices that require real-time remote access to transfer large files or content streams.
In addition, there is a super large traffic package with M2M traffic ranging from 8 GB to 100 GB, which is often used for devices that need an all-weather M2M connection to transmit a large amount of data. Typically, such M2M applications include backup and redundant links for asset management and video monitoring systems.
In addition, some M2M traffic packages allow users to accumulate traffic usage of multiple SIM cards. Therefore, even if one M2M device exceeds the package traffic range, it can be offset by the remaining traffic of another connected device. Moreover, according to different applications and operators, these traffic packages also provide users with different connection technologies to choose from: GPRS, 2G, 3G and LTE 4G data pipes.
summary
By deeply studying the two interrelated technologies of M2M and Internet of things communication, it can be found that they are quite different in network architecture and implementation requirements, but many components such as RF module, modem, switch, router and gateway are shared by them. Cellular connection and related traffic packages are another common point of these two networking technologies.
In any case, understanding these commonalities is very important to clarify the boundary between M2M and IOT system, because it can effectively consider the requirements of security, connection availability and reliability, interface options and RF stability in industrial automation design.
Source: digkey“
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