As we all know, there are many kinds of IoT communication protocols, they have different performance, communication speed, coverage, power and memory, and each protocol has its own advantages and disadvantages. This article mainly introduces some common communication modules in the IoT.
Analysis of Internet of Things Communication Protocols
IoT communication protocols fall into two broad categories:
One is the access protocol: generally responsible for networking and communication between devices in the subnet
One is the communication protocol: it is mainly a device communication protocol running on the traditional Internet TCP/IP protocol, which is responsible for data exchange and communication between devices through the Internet.
Physical layer, data link layer protocol
1. Long-distance cellular communication
1.1 2G/3G/4G communication protocols refer to the second, third and fourth generation mobile communication system protocols respectively.
Narrow Band Internet of Things (NB-IoT) has become an important branch of the Internet of Everything. NB-IoT is built on a cellular network and consumes only about 180kHz of bandwidth, and can be directly deployed on a GSM network, UMTS network or LTE network to reduce deployment costs and achieve smooth upgrades. Focusing on the Low Power Wide Coverage (LPWA) Internet of Things (IoT) market, NB-IoT is an emerging technology that can be widely used around 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 the NB-IoT network include smart parking, smart fire protection, smart water affairs, smart street lights, shared bicycles, and smart home appliances.
The fifth generation mobile communication technology is the latest generation of cellular mobile communication technology. The performance goals of 5G are high data rates, reduced latency, energy savings, lower costs, increased system capacity, and massive device connectivity.
Application scenarios: AR/VR, Internet of Vehicles, smart manufacturing, smart energy, wireless medical care, wireless home entertainment, connected drones, ultra-high-definition/panoramic live broadcast, personal AI assistance, and smart cities.
2. Long-distance non-cellular communication
Due to the rapid popularity of home WiFi routers and smartphones in the past few years, WiFi protocols have also been widely used in the field of smart homes. The biggest advantage of the WiFi protocol is that it can directly access the Internet. Compared with ZigBee, the smart home solution using the Wifi protocol eliminates the need for additional gateways. Compared with the Bluetooth protocol, it eliminates the need for mobile terminals such as mobile phones.
The coverage of commercial WiFi in public places such as urban public transportation and shopping malls has undoubtedly revealed the potential application of commercial WiFi in scenarios.
ZigBee is a wireless communication protocol for low-speed short-distance transmission. It is a highly reliable wireless data transmission network. The main features are low speed, low power consumption, low cost, support for a large number of online nodes, support for multiple online topologies, and low complexity. , fast, reliable and safe. ZigBee technology is a new type of technology, which appeared recently, mainly relying on wireless network for transmission.
The innate advantages of ZigBee technology make it gradually become a mainstream technology in the Internet of Things industry, and it has been widely used in industry, agriculture, smart home and other fields.
LoRa (LongRange) is a modulation technology that provides longer communication distances compared to similar technologies. LoRa gateways, smoke detectors, water monitoring, infrared detection, positioning, plug sockets, etc. are widely used in IoT products. As a narrowband wireless technology, LoRa uses time difference of arrival to achieve geolocation. Application scenarios of LoRa positioning: smart city and traffic monitoring, metering and logistics, agricultural positioning monitoring.
3. Near Field Communication
Radio Frequency Identification (RFID) is the abbreviation of RadioFrequencyIdentification. The principle is the non-contact data communication between the reader and the tag to achieve the purpose of identifying the target. The application of RFID is very wide, typical applications are animal chip, car chip anti-theft device, access control, parking lot control, production line automation, material management. A complete RFID system consists of three parts: reader, tag and data management system.
The Chinese full name of NFC is Near Field Communication Technology. NFC is developed on the basis of non-contact radio frequency identification (RFID) technology and combined with 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. The "near field" in the Chinese name of NFC refers to radio waves that are close to the electromagnetic field.
Application scenarios: It is used in access control, attendance, visitors, meeting check-in, patrol and other fields. NFC has functions such as human-computer interaction and machine-to-machine interaction.
Bluetooth technology is an open global specification 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 wirelessly exchange information among many devices, including mobile phones, PDAs, wireless headsets, notebook computers, and related peripherals. Using "Bluetooth" technology can effectively simplify the communication between mobile communication terminal devices, and can also successfully simplify the communication between the device and the Internet, so that data transmission becomes more rapid and efficient, and the road for wireless communication is widened.
4. Wired communication
USB, short for Universal Serial Bus (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 the PC field.
4.2 Serial communication protocol
The serial communication protocol refers to the relevant specifications that specify the content of the data packet, including the 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, commonly used protocols include RS-232, RS-422 and RS-485.
Serial communication refers to a communication method in which data is transmitted bit by bit through data lines between peripherals and computers. This communication method uses fewer data lines and can save communication costs in long-distance communication, but its transmission speed is lower than that of parallel transmission. Most computers (excluding notebooks) include two RS-232 serial ports. Serial communication is also a commonly used communication protocol for instrumentation equipment.
Ethernet is a computer local area network technology. The IEEE802.3 standard organized by the IEEE has formulated the technical standard of Ethernet, which stipulates the content of the protocol including the connection of the physical layer, the electronic signal and the medium access layer.
The MBus remote meter reading system (symphonicmbus) is a European standard 2-wire two-bus, mainly used for consumption measuring instruments such as heat meters and water meters.
Network layer, transport protocol
Internet Protocol Version 4 is the fourth revision in the development of the Internet Protocol and the first widely deployed version of the protocol. IPv4 is the core of the Internet and the most widely used version of the Internet Protocol
Internet Protocol version 6, because 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 for various access devices to connect to the Internet
Transmission Control Protocol (TCP, Transmission Control Protocol) is a connection-oriented, reliable, byte stream-based transport layer communication protocol. TCP is designed to accommodate a layered protocol hierarchy that supports multiple network applications. Reliable communication services are provided between pairs of processes in host computers connected to different but interconnected computer communication networks relying on TCP. TCP assumes that it can get simple, possibly unreliable, datagram service from lower-level protocols.
6LoWPAN is a low-speed wireless personal area network standard based on IPv6, namely IPv6overIEEE802.15.4.
Application layer protocol
1. MQTT protocol
MQTT (MessageQueueTelemetryTransport), translated into Chinese, is the telemetry transmission protocol, which mainly provides two message modes of subscription/publishing, which is more concise, lightweight, and easy to use, especially suitable for restricted environments (low bandwidth, high network latency, It is a standard transmission protocol of the Internet of Things (Internet of Things).
In many cases, including constrained environments, such as: Machine-to-Machine (M2M) communication and the Internet of Things (IoT). It is widely used in communicating sensors via satellite links, occasional dial-up medical devices, smart homes, and some miniaturized devices.
2. CoAP protocol
CoAP (Constrained Application Protocol) is a web-like protocol in the Internet of Things world, suitable for small and low-power sensors, switches, valves and similar components that need to be remotely controlled or monitored through standard Internet networks. response
3. REST/HTTP protocol
RESTful is a resource-based software architectural style. The so-called resource is an entity on the network, or a specific information on the network. A picture, a song is a resource. RESTful API is an implementation based on the HTTP protocol. (HTTP is an application layer protocol, which is characterized by simplicity and speed).
An application or design that meets the Rest specification is RESTful, and an API designed according to the Rest specification is called a RESTful API
4. DDS protocol
DDS (DataDistributionService) distributed real-time data distribution service middleware protocol, it is "TCP/IP" in distributed real-time network, used to solve the network protocol interconnection in real-time network, its role is equivalent to "bus on bus".
5. AMQP protocol
AMQP, the Advanced Message Queuing Protocol, is an application-layer standard advanced message queuing protocol that provides unified messaging services. It is an open standard for application-layer protocols and is designed for message-oriented middleware. Clients and message middleware based on this protocol can transmit messages, and are not limited by different client/middleware products and different development languages. Implementations in Erlang include RabbitMQ, etc.
6. XMPP protocol
XMPP is a protocol based on XML, a subset of the Standard Universal Markup Language, which inherits the flexibility of development in the XML environment. Therefore, XMPP-based applications are highly scalable. The extended XMPP can deal with the needs of users by sending extended information, and build applications such as content publishing systems and address-based services on top of XMPP.