The Internet of Things (IoT) is considered to be the third wave of development of the world’s information industry after computers and the Internet, and is also called the fourth technological revolution [1]. At present, most of the Internet of Things still rely on the Internet and mobile Internet, and the lack of dedicated network protocols for the Internet of Things has restricted the large-scale popularization of the Internet of Things to a certain extent. As a result, LowPower Wide-Area Network (LPWAN) came into being. Compared with traditional IoT communication technology, LPWAN technology has technical advantages such as wide coverage, long distance, massive connections, low power consumption, and low cost, and has become a new hot spot in current research and application development in the field of IoT [2]. Among the many LPWAN technologies, the most competitive technologies are LoRa and NB-IoT [3~5]. Among them, LoRa technology is an early development among LPWAN technologies, the technology is relatively mature, and it has a complete industrial chain.
LoRaWAN defines the communication protocol and system architecture, while LoRa defines the physical layer.
This is the typical system architecture of LoRaWAN node.
Architettura della rete LoRa
Most modern IoT LAN technologies use mesh network architecture. By using a mesh network, the system can increase the communication range and cell size of the network. However, nodes in a mesh network also have the additional responsibility of forwarding messages to other nodes (often unrelated to them). This can severely impact your device’s battery life.
LoRaWAN uses a star topology because it improves battery life when using remote connections.
The LoRa network consists of several elements.
LoRa Nodes/Endpoints: LoRa endpoints are sensors or applications that perform sensing and control. These nodes are usually located in remote locations. Examples, sensors, tracking devices, etc.
LoRa Gateway: Unlike cellular communications where mobile devices are associated with serving base stations, LoRaWAN nodes within LoRaWAN nodes are associated with specific gateways. Instead, any data sent by a node is sent to all gateways, and each gateway that receives the signal sends it to a cloud-based network server.
Typically, gateways and network servers are connected via some backhaul (cellular, Wi-Fi, Ethernet, or satellite).
Web Server: The web server has all the intelligence. It filters duplicate packets from different gateways, performs security checks, and sends ACK to the gateway. Finally, if the packet is intended for an application server, the network server sends the packet to the specific application server.
This type of network uses all gateways to send the same packets to the network server, without switching or switching. This is useful for asset tracking applications where assets are moved from one location to another.
LoRa device categories
Like other networks, end devices can have different functions based on device class, and end nodes in a LoRaWAN network can have different device classes.
Each device class is a compromise between network downlink communication latency and battery life.
Grade A: Best for battery level sensors
● Most energy efficient and can have many years of battery life
● All devices in the LoRaWAN network support this device class
● Downlink is only available after the sensor transmits something
Class B: Terminal equipment receiving slots with schedule
● Open additional receive slots at scheduled times.
● Receive time-synchronized beacons from the gateway
Class C: Terminal equipment with maximum receiving slots
● Open the receiving window continuously
● RX is only turned off when the device is transmitting
In October 2016, a large-scale IoT DDoS test attack occurred in the United States, causing the entire Internet in the eastern United States to be “offlined.” In July 2017, domestic public security agencies successfully eliminated the first criminal gang that spread home camera cracking and intrusion software online. Compared with traditional Internet security issues, Internet of Things security issues will not only cause economic losses, privacy leaks and other hazards, but also directly threaten life safety.
Keywords: lora digital transmission terminal