1. What is LoRa (abbreviation for long range) is a spread spectrum modulation technology developed from chirp spread spectrum (CSS) technology. LoRa technology is a long-range, low-power wireless platform that has become the wireless transmission technology for Internet of Things (IoT) networks worldwide.
2. The characteristics of LoRa technology LoRa is one of the popular technologies specially designed for wireless transmission of the Internet of Things. The LoRa network specification includes LoRa protocol physical layer technology (non-open technology provided by semtech) and LoRAWAN (MAC multimedia access layer) open layer protocol.
3. What is LoRaWAN? LoRaWAN is a Low Power Wide Area Network (LPWAN) standard based on the open-source MAC layer protocol introduced by the LoRa Alliance. This technology can provide local, national or global networks for battery-operated wireless devices.
LoRaWAN network entities are divided into four parts: terminal nodes, gateways, LoRaWAN servers, and user servers. End Node: End nodes are generally various sensors for data collection, switch control, etc. Gateway: LoRa gateway, which encapsulates and forwards the collected node data. NetworkServer: Mainly responsible for the integrity verification of uplink and downlink data packets. ApplicationServer: Mainly responsible for network activation of OTAA devices and encryption and decryption of application data. CustomerServer: Receives data from nodes from AS, performs business logic processing, and sends data to nodes through the API interface provided by AS.
LoRa protocol layers Application, MAC, Modulation, where Application is the application layer, user-defined application programs and software interfaces based on LoRaWAN technology. The common LoRaWAN protocol is the LoRaMAC protocol. The terminal types defined by the protocol are ClassA, ClassB, and ClassC. Class A terminal two-way (duplex) communication terminal equipment. Terminal equipment allows two-way communication, which can be understood as full-duplex communication. The uplink transmission of each terminal device will be accompanied by two downlink receiving windows. The transmission channel of the terminal equipment is based on its own communication requirements, and the fine-tuning is based on a random time reference (ALOHA protocol). The terminal device to which A belongs has the lowest power consumption during application. Class B terminals are two-way communication terminal equipment with preset receiving channels. This type of device will open the remaining receiving window in the preset time. In order to achieve this purpose, the terminal device will receive a Beacon from the gateway synchronously, and synchronize the time of the base station and the module through the Beacon. In this way, the server is made aware that the terminal device is receiving data. Class C terminal is a two-way communication terminal device with the largest receiving channel. This terminal device continuously opens the receiving window and closes it only when transmitting.
4. Star topology The star topology relays messages to the central server through gateways, and each end node transmits data to multiple gateways. The gateway then forwards the data to the web server where redundancy detection, security checks and message scheduling are performed. Advantages of lora network topology: easy to track. Since an end node sends data to multiple gateways, no gateway-to-gateway communication is required. public network. This unpaired relationship leaves the central server to resolve conflicts. It is more suitable for deploying public networks.
5. LoRa relay network When the LoRa module is used in practice, it is necessary to keep the network connection smooth to ensure the normal transmission and reception of data because the transmission distance is not enough. At this time, there is a way of relay networking to solve the problem of insufficient communication distance. Relay networking can be understood as a "bridge" method, because the distance is too far to complete the normal sending and receiving of data at one time. Configure a device in the middle of its sending and receiving, and configure this device as a relay mode. At this time, the distance that was too far before is split into two parts to achieve a perfect data transmission "bridge" function. In the process of relaying, it is only necessary to integrate the addresses and settings of the two into the "bridge" device, that is, the addresses of the two can be combined with high and low bytes, and finally the wireless bridge network communication between the two can be successfully established. Relays can be divided into first-level relays, second-level relays, third-level relays . . . multi-level relays. According to this relay method, theoretically, data can be transmitted over an unlimited distance. Ebyte focuses on the wireless communication industry of the Internet of Things, always pays attention to the development of the communication technology and industry of the Internet of Things, and is at the forefront of the wireless communication technology of the Internet of Things. Maintain close cooperation with the above-mentioned chip manufacturers to develop simple, easy-to-use, high-quality and low-cost wireless communication modules. Including WiFi module, Bluetooth module, Zigbee module, NB-iot module, 4G module, private wireless module, LoRa and LoRaWAN module.