LoRa (Long Range) technology is a low-power, long-distance wireless communication technology that can achieve communication distances of several kilometers at low power. Its principle is based on a method called spread spectrum technology. By using spread spectrum modulation technology at the transmitting and receiving ends, the low-speed data stream is converted into a high-speed, broadband signal, and is restored through related despreading technology at the receiving end. . This method allows signals to be transmitted at lower power and is resistant to interference and multipath effects, enabling long-distance communications.
Specifically, the physical layer of LoRa technology uses a spread spectrum modulation technology called CSS (Chirp Spread Spectrum), which convolves the original data stream with a baseband signal called chirp to form a wideband, low power signal. At the transmitting end, the original data stream is converted into a chirp signal, which is modulated and power amplified by the radio frequency front end and launched into the air. At the receiving end, the received signal is demodulated and filtered by the radio frequency front-end and then sent to a module called a spread spectrum despreader for despreading. During the despreading process, the despreader at the receiving end converts the wideband signal into a narrowband original data stream by matching the spreading code used at the transmitting end. This method can effectively improve the signal transmission distance and anti-interference ability, while reducing power consumption and complexity.
The MAC layer of LoRa technology uses a conflict-free protocol called ALOHA, which sends data packets in different time slices in a random manner to avoid conflicts between senders. At the same time, in order to further improve the reliability and flexibility of the network, LoRa technology also introduces a communication protocol called LoRaWAN.
Long-distance communication: LoRa technology can achieve long-distance communication at lower power. The communication distance can reach several kilometers. It has wide area and deep penetration, and can achieve comprehensive indoor and outdoor coverage.
Low power consumption: Due to the use of spread spectrum technology and ALOHA protocol, LoRa technology has low power consumption and can achieve long-term operation, so it is suitable for battery-powered devices. In LoRaWAN technology, the device sleeps most of the time and wakes up only when there is data transmission, thereby achieving low power consumption.
Anti-interference: LoRa technology uses spread spectrum technology to make the signal resistant to interference and multipath effects, thus improving the reliability of communication.
Large capacity: LoRa technology can process data from multiple nodes at the same time and has the advantage of large capacity.
Security: LoRa technology uses the AES-128 encryption algorithm to ensure data security.
LoRaWAN technology principle
LoRaWAN technology is a network protocol based on LoRa technology. It provides a standardized IoT protocol stack that can connect and manage a large number of LoRa devices. LoRaWAN technology uses star and mesh topologies, with one or more gateways connected to the Internet to receive and send data from LoRa devices. It is mainly used for long-distance, low-power consumption, and low-data-rate IoT device communications.
The core of LoRaWAN technology is the MAC layer protocol, which adds a complete protocol stack based on the LoRa physical layer, including the physical layer, MAC layer, network layer and application layer.
physical layer
The LoRaWAN physical layer is based on LoRa technology, which uses frequency shift keying (FSK) and spread spectrum technology. When transmitting data, the data is first spread spectrum, then modulated by FSK, and finally sent out. This method can improve the anti-interference ability of the signal and make the data transmission distance longer.
MAC layer
The MAC layer protocol of LoRaWAN mainly includes the following parts:
Random access: LoRaWAN devices can access the network at any time without predetermined negotiation with the gateway. This method allows the device to quickly access the network.
Adaptive data rate: LoRaWAN devices can adaptively adjust the transmission rate according to the current network environment to ensure transmission reliability and stability.
Confirmation mechanism: LoRaWAN devices can choose whether to receive a confirmation frame to confirm whether the data is successfully sent.
Data encryption: LoRaWAN uses the AES 128-bit encryption algorithm to encrypt data to ensure the security of data transmission.
Network layer
LoRaWAN's network layer protocol uses an IPv6-based protocol, which allows LoRaWAN devices to address and communicate through IPv6 addresses. In addition, LoRaWAN's network layer protocol also supports network service discovery, security protection, node management and other functions.
Application layer
LoRaWAN's application layer protocol is designed for different application scenarios. It supports a variety of different application protocols, such as COAP, MQTT, etc., making application development more convenient.
LoRaWAN is a low-power, long-distance wireless communication protocol designed to provide reliable, secure, and low-cost communication solutions for IoT applications. The main features of LoRaWAN technology are as follows:
Long-distance communication: LoRaWAN technology uses LoRa modulation technology to enable long-distance communication in complex environments such as cities and rural areas, with a coverage range of several kilometers to dozens of kilometers.
Low power consumption: LoRaWAN devices are usually battery powered, so power consumption control is very important. LoRaWAN technology adopts a low-power design, which greatly extends the battery life of the device, often for years or even decades.
Large capacity: LoRaWAN technology has the characteristics of large capacity and can connect a large number of devices at the same time to achieve many-to-many communication.
Security: LoRaWAN technology provides multi-level security, including physical layer encryption, MAC layer encryption and application layer encryption, etc. to ensure the confidentiality and integrity of data.
Flexibility: LoRaWAN technology is highly flexible and can be customized according to application scenarios. At the same time, it also has good interoperability and can be seamlessly integrated with other communication technologies.
Low cost: Because LoRaWAN technology uses a simple hardware structure and an open communication protocol, the cost is relatively low. At the same time, its low power consumption design can also save equipment maintenance costs.
In general, the advantages of LoRaWAN technology lie in its long-distance communication, low power consumption, large capacity, security, flexibility and low cost, making it one of the very important communication technologies in IoT applications.
To sum up, although LoRa and LoRaWAN are two different technologies, they both have the advantages of long-distance transmission and low power consumption, so they are widely used in the field of Internet of Things. For developers and application manufacturers, understanding the principles and characteristics of LoRa and LoRaWAN can better choose the technology suitable for their own application scenarios and design efficient and stable wireless communication equipment.