Fundamentals of IoT Network Transmission Protocols

Recently, I have been exploring smart network systems and have summarized the fundamentals of IoT network transmission protocols as follows:

Important Protocol Standards

There are several available IoT communication protocols, each with different performance, data rates, coverage, power consumption, and memory requirements. Each protocol has its own advantages and disadvantages to varying degrees. Some communication protocols are suitable only for small household appliances, while others can be used for large smart city projects. IoT communication protocols can be divided into two main categories:

• One category is access protocols: generally responsible for networking and communication between devices within a subnet.

• The other category is communication protocols: primarily device communication protocols that operate on traditional Internet TCP/IP protocols, responsible for data exchange and communication between devices over the Internet.

Access protocols and communication protocols are two different levels of protocols in network communication. They are interrelated but have clear divisions of labor and distinctions, as detailed below:

1. Hierarchical Relationship

(1) Communication Protocols are the foundational rules of network communication, defining the format, process, and interaction methods for data transmission between different devices, such as TCP/IP, HTTP, MQTT, etc. These protocols determine how data is transmitted and processed across different layers, including the physical layer, data link layer, and network layer.

(2) Access Protocols are application extensions of communication protocols in specific scenarios, mainly used for identity authentication, data format conversion, and interaction process definition when devices access networks or platforms. For example, when the MQTT protocol connects devices to an IoT platform, it requires specific access protocols (such as device registration, heartbeat mechanisms, etc.) to complete the connection and data exchange between devices and the platform.

2. Complementary Functions

(1) Communication Protocols focus on data transmission efficiency, reliability, and security, ensuring correct data transmission between different devices.

(2) Access Protocols are more concerned with the connection process between devices and networks or platforms, including device authentication, data format adaptation, resource allocation, etc., ensuring that devices can smoothly connect and participate in communication.

3. Application Scenarios

(1) Communication Protocols are suitable for a wide range of network communication scenarios, such as the Internet, local area networks, and IoT.

(2) Access Protocols are typically related to specific platforms or services, such as device access protocols for IoT platforms and access protocols for cloud services.

4. Physical Layer and Data Link Layer Protocols

(1) Wireless Communication

a. 2G/3G/4G Communication Protocols refer to the second, third, and fourth generation mobile communication system protocols.b. NB-IoT Narrowband Internet of Things (NB-IoT) has become an important branch of the Internet of Everything network. NB-IoT is built on cellular networks, consuming approximately 180kHz of bandwidth, and can be directly deployed on GSM, UMTS, or LTE networks to reduce deployment costs and achieve smooth upgrades. NB-IoT focuses on the low-power wide-area (LPWA) IoT market and is an emerging technology that can be widely applied globally. It features wide coverage, multiple connections, fast rates, low costs, low power consumption, and excellent architecture.NB-IoT network applications include smart parking, smart firefighting, smart water management, smart street lighting, shared bicycles, and smart appliances.c. 5G The fifth generation mobile communication technology is the latest generation of cellular mobile communication technology. The performance goals of 5G include high data rates, reduced latency, energy savings, cost reduction, increased system capacity, and large-scale device connectivity.Image generated by AI Application scenarios: AR/VR, vehicle networking, smart manufacturing, smart energy, wireless medical, wireless home entertainment, connected drones, ultra-high-definition/panoramic live streaming, personal AI assistance, smart cities.d. WiFi Due to the rapid proliferation of home WiFi routers and smartphones in recent years, the WiFi protocol has also been widely used in the smart home field. The biggest advantage of the WiFi protocol is its ability to connect directly to the Internet. Compared to ZigBee, smart home solutions using WiFi protocols eliminate the need for additional gateways, and compared to Bluetooth protocols, they do not rely on mobile terminals such as smartphones.Commercial WiFi coverage in urban public transport, shopping malls, and other public places clearly reveals the potential of commercial WiFi applications.e. ZigBeeZigBee is a low-speed, short-range wireless communication protocol that is a highly reliable wireless data transmission network. Its main features include low speed, low power consumption, low cost, support for a large number of online nodes, support for various online topologies, low complexity, fast, reliable, and secure. ZigBee technology is a new technology that has recently emerged, primarily relying on wireless networks for transmission, enabling short-range wireless connections, and belongs to wireless network communication technology.The inherent advantages of ZigBee technology have made it a mainstream technology in the IoT industry, with large-scale applications in industrial, agricultural, and smart home fields.f. LoRaLoRa™ (Long Range) is a modulation technology that provides longer communication distances compared to similar technologies. LoRa gateways, smoke detectors, water monitoring, infrared detection, positioning, and power strips are widely used IoT products. As a narrowband wireless technology, LoRa uses time-of-arrival differences to achieve geographic positioning. LoRa positioning application scenarios include smart cities and traffic monitoring, metering and logistics, and agricultural positioning monitoring.g. RFIDRadio Frequency Identification (RFID) is the abbreviation for Radio Frequency Identification. Its principle is non-contact data communication between a reader and a tag to achieve the purpose of identifying the target. RFID has a wide range of applications, with typical applications including animal chips, automotive chip anti-theft devices, access control, parking lot management, production line automation, and material management. A complete RFID system consists of three parts: a reader, an electronic tag, and a data management system.h. NFCNFC stands for Near Field Communication technology. NFC is developed based on non-contact RFID technology, combined with wireless interconnection technology, providing a very secure and convenient communication method for various electronic products that are becoming increasingly popular in our daily lives. The term “near field” in NFC refers to the radio waves of the nearby electromagnetic field.Application scenarios: used in access control, attendance, visitor management, conference sign-in, patrol, and other fields. NFC has functions such as human-machine interaction and machine-to-machine interaction.i. BluetoothBluetooth technology is an open global specification for wireless data and voice communication, based on low-cost short-range wireless connections, establishing a communication environment for fixed and mobile devices. Bluetooth enables wireless information exchange between numerous devices, including mobile phones, PDAs, wireless headsets, laptops, and related peripherals. By utilizing Bluetooth technology, communication between mobile communication terminal devices can be effectively simplified, and communication between devices and the Internet can also be successfully simplified, making data transmission faster and more efficient, thus broadening the path for wireless communication.（2）Wired Communicationa. USBUSB, short for Universal Serial Bus, is an external bus standard used to specify the connection and communication between computers and external devices. It is an interface technology applied in the PC field.b. Serial Communication ProtocolThe serial communication protocol specifies the content of data packets, which includes start bits, main data, check bits, and stop bits. Both parties need to agree on a consistent data packet format to send and receive data normally. Common protocols in serial communication include RS-232, RS-422, and RS-485.Serial communication refers to a communication method where data is transmitted bit by bit between peripherals and computers through data lines. This communication method uses fewer data lines, which can save communication costs 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 commonly used communication protocol for instruments and equipment.c. EthernetEthernet is a computer local area network technology. The IEEE organization has established the IEEE 802.3 standard, which defines the technical standards for Ethernet, including the physical layer wiring, electronic signals, and media access layer protocols.(3) Wired/Wireless CommunicationMBusMBus remote meter reading system (symphonic mbus) is a two-wire bus standard in Europe, mainly used for consumption measurement instruments such as heat meters and water meters.5. Network Layer and Transport Protocols(1) IPv4Internet Protocol version 4 is the fourth revision of the Internet Protocol development process and the first version of this protocol to be widely deployed. IPv4 is the core of the Internet and the most widely used version of the Internet protocol.(2) IPv6Internet Protocol version 6 was developed to address the major issue of limited network address resources in IPv4, which severely restricts the application and development of the Internet. The use of IPv6 not only solves the problem of the number of network address resources but also addresses the barriers to connecting multiple access devices to the Internet.(3) TCPTransmission Control Protocol (TCP) is a connection-oriented, reliable, byte-stream-based transport layer communication protocol. TCP is designed to adapt to a layered protocol hierarchy that supports multiple network applications. It provides reliable communication services between paired processes in main computers connected to different but interconnected computer communication networks. TCP assumes it can obtain simple, possibly unreliable datagram services from lower-level protocols.(4) 6LoWPAN6LoWPAN is a low-power wireless local area network standard based on IPv6, specifically IPv6 over IEEE 802.15.4.6. Application Layer Protocols(1) MQTT ProtocolMQTT (Message Queue Telemetry Transport) is a telemetry transmission protocol that provides two message modes: publish/subscribe, which is more concise, lightweight, and easy to use, especially suitable for message distribution in constrained environments (low bandwidth, high network latency, unstable network communication), and is a standard transmission protocol for the Internet of Things (IoT).In many cases, including constrained environments such as machine-to-machine (M2M) communication and the Internet of Things (IoT), it has been widely used in satellite link communication sensors, occasionally dial-up medical devices, smart homes, and some miniaturized devices.(2) CoAP ProtocolCoAP (Constrained Application Protocol) is a web-like protocol in the IoT world, suitable for small low-power sensors, switches, valves, and similar components that require remote control or monitoring over standard Internet networks. Servers may not respond to unsupported types.(3) REST/HTTP ProtocolRESTful is a software architectural style based on resources. A resource is an entity on the network or specific information on the network. An image or a song is a resource. RESTful API is an implementation based on the HTTP protocol (HTTP is an application layer protocol characterized by simplicity and speed).Applications or designs that meet REST specifications are RESTful, and APIs designed according to REST specifications are called RESTful APIs.(4) DDS ProtocolDDS (Data Distribution Service) is a middleware protocol for distributed real-time data distribution service, serving as the “TCP/IP” in distributed real-time networks, used to solve network protocol interconnection in real-time networks, functioning as a “bus on the bus.”(5) AMQP ProtocolAMQP, or Advanced Message Queuing Protocol, is an open standard for application layer protocols that provides unified messaging services, designed for message-oriented middleware. Clients based on this protocol can exchange messages with message middleware without being restricted by different products or development languages. Implementations in Erlang include RabbitMQ, among others.(6) XMPP ProtocolXMPP is a protocol based on a subset of the standard generalized markup language XML, inheriting the flexible development nature in XML environments. Therefore, applications based on XMPP have strong scalability. After expansion, XMPP can handle user needs by sending extended information and establish applications such as content publishing systems and address-based services on top of XMPP.7. Comparison of Some Communication Protocols(1) Comparison of NB-IoT Protocol and LoRa Protocol

First, frequency bands. LoRa operates in unlicensed frequency bands below 1GHz, requiring no additional fees for application, while NB-IoT and cellular communication use licensed frequency bands below 1GHz, which incur charges.Second, battery life. LoRa modules have unique characteristics in handling interference, network overlap, scalability, etc., but cannot provide the same quality of service as cellular protocols. Due to service quality considerations, NB-IoT cannot offer battery life similar to LoRa.Third, device costs. For terminal nodes, the LoRa protocol is simpler, easier to develop, and has better applicability and compatibility with microprocessors compared to NB-IoT. Additionally, low-cost, relatively mature LoRa modules are already available on the market, with upgraded versions expected to be released continuously.Fourth, network coverage and deployment timelines. The NB-IoT standard was announced in 2016, and aside from network deployment, the corresponding commercialization and industrial chain establishment require more time and effort to explore. The entire industrial chain of LoRa is relatively mature, and products are in a “ready-to-launch” state, with many countries globally conducting or completing nationwide network deployments.(2) Comparison of Bluetooth, WiFi, and ZigBee Protocols

Currently, WiFi’s advantage is its widespread application, having become common in thousands of households; ZigBee’s advantage is low power consumption and self-organizing networks; UWB (Ultra-Wideband) wireless communication technology’s advantage is transmission speed; Bluetooth’s advantage is simple networking. However, these three technologies also have their shortcomings, and no single technology can fully meet all the requirements of smart homes.The emergence of Bluetooth technology has made short-range wireless communication possible, but its complex protocol, high power consumption, and high costs are not well-suited for industrial control and home networks that require low costs and low power consumption. Especially, Bluetooth’s biggest obstacle is its limited transmission range, generally effective within about 10 meters, and issues such as weak anti-interference capability and information security concerns are major factors restricting its further development and large-scale application.WiFi is also a short-range wireless transmission technology that can connect to wireless signals at any time, offering strong mobility, making it suitable for use in office and home environments. However, WiFi also has a fatal flaw. Since WiFi uses radio frequency technology to send and receive data through the air, it is relatively susceptible to external interference.ZigBee, on the other hand, is an internationally accepted wireless communication technology, with each network port capable of connecting up to 65,000 ports, making it suitable for use in homes, industry, agriculture, and other fields, while Bluetooth and WiFi networks can only connect 10 ports, which clearly cannot meet household needs. ZigBee also has advantages in low power consumption and low cost.

(3) Modbus

• Features: A universal industrial communication protocol that supports multiple physical layers such as RS-485, TCP/IP, etc., suitable for PLCs, sensors, and other devices.

• Advantages: High flexibility, high transmission rates (up to 115.2 kbps), supports complex network topologies.

• Disadvantages: No built-in power supply function, requires additional power lines.

(4) RS-485

• Features: Half-duplex serial communication, commonly used in industrial automation.

• Advantages: Long transmission distance (up to 1200 meters), strong anti-interference capability, supports multi-point communication.

• Disadvantages: Requires four-wire wiring, higher costs.

(5) NB-IoT (Narrowband IoT)

• Features: A low-power wide-area network (LPWAN) technology based on cellular networks, suitable for smart water meters, electric meters, etc.

• Advantages: Wireless communication, wide coverage (dependent on base stations), supports massive device access (thousands of devices can connect to a single base station).

• Disadvantages: Dependent on operator networks, potential communication cost issues.

(6) LoRa

• Features: Long-distance, low-power wireless communication technology, suitable for decentralized deployment scenarios.

• Advantages: Ultra-long communication distance (up to 10 km), low power consumption, suitable for rural or remote areas.

• Disadvantages: Lower transmission rates (<50 kbps), requires self-built gateways.

(7) SMBus (System Management Bus)

• Features: A subset based on I2C, mainly used for power management in PCs and embedded systems.

• Advantages: Standardized, supports automatic addressing, suitable for battery management.

• Disadvantages: Lower transmission rates (typically 100 kHz), mainly used for short-distance communication.