How Much Do You Know About The Internet of Things (IOT) Communication Protocol?

Communication is very common and key to the Internet of things. Both short-range wireless transmission technology and mobile communication technology affect the development of the Internet of things. In communication, communication protocol is particularly important, which is the rules and conventions that both entities must follow to complete communication or services.

There are many kinds of Internet of things communication protocols, which have different performance, communication rate, coverage, power and memory, and each protocol has its own advantages and disadvantages. This article mainly introduces some common Internet of things communication protocols for everyone to understand.

Internet of things communication protocols fall into two categories:

One is access protocol, which is generally responsible for networking and communication between devices in the subnet.

One is the communication protocol: it is mainly the device communication protocol running on the traditional Internet tcp/ip protocol, which is responsible for the data exchange and communication of devices through the Internet.

Physical layer, data link layer protocol

1. Long distance cellular communication

(1) 2g/3g/4g communication protocols refer to the second, third and fourth generation mobile communication system protocols respectively

(2) NB-IoT

The narrow band Internet of things (NB IOT) has become an important branch of the Internet of things. NB IOT is built in a cellular network and only consumes about 180khz bandwidth. It can be directly deployed in GSM network, umts network or LTE network to reduce deployment costs and achieve smooth upgrade. Focusing on the low power consumption and wide coverage (lpwa) Internet of things (IOT) market, Nb IOT is an emerging technology that can be widely used in the world. It has the characteristics of wide coverage, multiple connections, fast speed, low cost, low power consumption and excellent architecture.

Application scenarios: scenario applications brought by NB IOT network include intelligent parking, intelligent fire fighting, intelligent water affairs, intelligent street lamps, shared bicycles and intelligent appliances.

(3) 5G

The fifth generation mobile communication technology is the latest generation of cellular mobile communication technology. The new generation broadband mobile communication technology, which has the characteristics of high speed, low delay and large connection, is the network infrastructure to realize man-machine and object interconnection. The International Telecommunication Union (ITU) has defined three categories of 5g application scenarios, namely, enhanced mobile broadband (embB), ultra high reliable low delay communication (urllc) and mass machine communication (mmtc).

Enhanced mobile broadband (embB) is mainly aimed at the explosive growth of mobile Internet traffic, providing more extreme application experience for mobile Internet users; Ultra high reliability and low time delay communication (urllc) is mainly used in vertical industries with high requirements for time delay and reliability, such as industrial control, telemedicine and automatic driving; Mass machine communication (mmtc) is mainly aimed at smart cities, smart homes, environmental monitoring and other applications that aim at sensing and data acquisition.

In order to meet the needs of 5g diversified application scenarios, the key performance indicators of 5g are more diversified. ITU has defined eight key performance indicators of 5g. Among them, high-speed rate, low delay and large connection have become the most prominent features of 5g. The user experience rate reaches 1Gbps, the delay is as low as 1ms, and the user connection capacity reaches 1million connections / km2.

Application scenarios: ar/vr, Internet of vehicles, intelligent manufacturing, smart energy, wireless medical treatment, wireless home entertainment, networked UAV, UHD / panoramic live broadcast, personal AI assistance, smart city.

2. Long distance non cellular communication

(1) WiFi

Due to the rapid popularity of home WiFi routers and smart phones in previous years, WiFi protocol has also been widely used in the field of smart home. The biggest advantage of WiFi protocol is that it can directly access the Internet. Compared with ZigBee, the smart home solution using WiFi protocol eliminates the need for additional gateways. Compared with Bluetooth protocol, it eliminates the need for mobile terminals such as mobile phones.

The coverage of commercial WiFi in urban public transport, shopping malls and other public places undoubtedly shows the potential of commercial WiFi for scene application.

(2) ZigBee

ZigBee is a low-speed and short-distance wireless communication protocol. It is a highly reliable wireless data transmission network. Its main features are low speed, low power consumption, low cost, support for a large number of network nodes, support for a variety of network topologies, low complexity, fast, reliable and safe. ZigBee technology is a new technology. It has emerged recently. It mainly relies on wireless network for transmission. It can connect wirelessly in a short distance. It belongs to wireless network communication technology.

ZigBee technology has inherent advantages, which makes it gradually become a mainstream technology in the Internet of things industry, and has been widely applied in industries, agriculture, smart home and other fields.

(3) LoRa

Lora (longrange) is a modulation technology that provides a longer communication distance than similar technologies. Lora gateway, smoke detection, water monitoring, infrared detection, positioning, row and plug are widely used in IOT products. As a narrow-band wireless technology, Lora uses time difference of arrival to realize geographic location. Application scenarios of Lora positioning: smart city and traffic monitoring, measurement and logistics, and agricultural positioning monitoring.

3. Short range communication

(1) RFID

Radio frequency identification (RFID) is the abbreviation of radio frequency identification. Its principle is that the reader and the tag communicate with each other in a non-contact way, so as to achieve the purpose of identifying the target. RFID is widely used. Typical applications include animal chip, automobile chip anti-theft device, access control, parking lot control, production line automation and material management. The complete RFID system consists of reader, tag and data management system.

(2) NFC

The full Chinese name of NFC is near field communication technology. NFC is developed on the basis of non-contact radio frequency identification (RFID) technology and wireless interconnection technology. It provides a very safe and fast communication method for various electronic products that are becoming more and more popular in our daily life. "Near field" in the Chinese name of NFC refers to radio waves adjacent to electromagnetic fields.

Application scenario: used in the fields of access control, attendance, visitors, meeting sign in, guard tour, etc. NFC has the functions of human-computer interaction and inter machine interaction.

(3) Bluetooth

Bluetooth technology is an open global standard for wireless data and voice communication. It is a special short-range wireless technology connection based on low-cost short-range wireless connection to establish a communication environment for fixed and mobile devices.

Bluetooth can exchange wireless information among many devices, including mobile phones, PDAs, wireless headsets, laptops, and related peripherals. Using "Bluetooth" technology, it can effectively simplify the communication between mobile communication terminal devices, and also successfully simplify the communication between devices and the Internet, so that data transmission becomes more rapid and efficient, and broaden the way for wireless communication.

4. Wired communication

(1) USB

USB, the abbreviation of universal serial bus in English, is an external bus standard used to regulate the connection and communication between computers and external devices. It is an interface technology applied in PC field.

(2) Serial communication protocol

Serial port communication protocol refers to the relevant specifications that specify the contents of data packets, including start bit, main data, check bit and stop bit. Both parties need to agree on a consistent data packet format to send and receive data normally. In serial communication, the commonly used protocols include RS-232, RS-422 and RS-485.

Serial port communication is a kind of communication between peripherals and computers, which transmits data by bit through data lines. This communication mode uses less data lines, which can save communication cost in long-distance communication, but its transmission speed is lower than parallel transmission. Most computers (excluding laptops) contain two RS-232 serial ports. Serial communication is also a common communication protocol for instruments and equipment.

(3) Ethernet

Ethernet is a computer LAN technology. The IEEE 802.3 standard organized by IEEE establishes the technical standard of Ethernet, which specifies the contents of the physical layer connection, electronic signal and media access layer protocol.

(4) MBus

MBus remote meter reading system (Symphonic MBus) is a European standard 2-wire 2-bus, which is mainly used for consumption measuring instruments such as heat meter and water meter series.

Network layer, transmission protocol

1.IPv4

The fourth version of Internet communication protocol is the fourth revised version in the development process of internet protocol and the first widely deployed version of this protocol. IPv4 is the core of the Internet and the most widely used Internet Protocol version

2.IPv6

For the 6th edition of internet protocol, the biggest problem of IPv4 is the limited network address resources, which seriously restricts the application and development of the Internet. The use of IPv6 can not only solve the problem of the number of network address resources, but also solve the obstacles of various access devices connecting to the Internet

3.TCP

Transmission control protocol (TCP) is a connection oriented, reliable and byte stream based transport layer communication protocol. TCP is designed to adapt to the hierarchical protocol hierarchy supporting multi network applications. The paired processes in the host computers connected to different but interconnected computer communication networks rely on TCP to provide reliable communication services. TCP assumes that it can obtain simple and possibly unreliable datagram services from lower level protocols.

4.6 LoWPAN

6LoWPAN is a low-speed wireless personal area network standard based on IPv6, that is, IPv6 over IEEE 802.15.4.

Application layer protocol

1. Mqtt protocol

Mqtt (message queue telemetry transport), translated into Chinese, is a telemetry transmission protocol. It mainly provides two message modes of subscription / publishing. It is simpler, lighter and easy to use. It is especially suitable for message distribution in restricted environments (low bandwidth, high network delay and unstable network communication). It is a standard transmission protocol of the Internet of things.

In many cases, including restricted environments, such as machine to machine (M2M) communication and Internet of things (IOT). It has been widely used in communication sensors through satellite links, occasionally dialing medical devices, smart homes, and some miniaturized devices.

2. COAP agreement

COAP (constrained Application Protocol) is a web like protocol in the world of the Internet of things. It is applicable to small low-power sensors, switches, valves and similar components that need to be remotely controlled or monitored through a standard Internet network. The server may not respond to unsupported types

3. Rest/http protocol

Restful is a resource-based software architecture style. The so-called resource is an entity on the network, or a specific information on the network. A picture or a song is a resource. Restful API is an implementation based on HTTP protocol. HTTP is an application layer protocol characterized by simplicity and rapidity.

Applications or designs that meet the rest specification are restful. APIs designed according to the rest specification are called restful APIs

4. DDS protocol

DDS (data distribution service) distributed real-time data distribution service middleware protocol, which is the "tcp/ip" in the distributed real-time network, is used to solve the network protocol interconnection in the real-time network, and its role is equivalent to the "bus on the bus".

5. AMQP protocol

AMQP, or advanced message queuing protocol, is an application layer standard advanced message queuing protocol that provides unified messaging services. It is an open standard of application layer protocols and is designed for message oriented middleware. The client and message oriented middleware based on this protocol can deliver messages, which is not limited by different products and development languages of the client / middleware. The implementations in Erlang include rabbitmq and so on.

6. XMPP protocol

XMPP is a protocol based on subset XML of standard general markup language. It inherits the flexible development in XML environment. Therefore, applications based on XMPP have super scalability. After the extension, XMPP can handle the needs of users by sending extended information, and establish applications such as content publishing system and address based services at the top of XMPP.

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