LoRa technology explanation and analysis of advantages and disadvantages

Introduction to LoRa

LoRa communication technology is one of the short-distance communications in the Internet of Things communication technology. The same short-distance communication technologies include Bluetooth, WIFI, Zigbee, etc.

LoRa is the abbreviation of Long Range in English. It is a type of Low PowerWide Area Network (LPWAN) communication technology. It is an ultra-long-distance low-power data transmission technology released by Semtech in 2013. In the past, before the emergence of LPWAN, it seemed that the only choice was between long distance and low power consumption. The emergence of LoRa wireless technology has changed the trade-off between transmission distance and power consumption. It can not only achieve long-distance transmission, but also have the advantages of low power consumption and low cost. The LoRa network is formed as shown in the figure below. Remote nodes can connect to the back-end network server through multiple gateways, upload data and send it to the cloud or server. In the LoRa network, each node is not connected to each other. It must first be connected to the gateway before it can connect to the central host, or transmit data to another node through the central host. Messages from terminal nodes can be transmitted to multiple gateways at the same time, and messages can also be further extended through bridges between gateways.

LoRa network composition

The LoRa network is mainly composed of four parts: terminal (can have built-in LoRa module), gateway (or base station), server and cloud. Application data can be transferred in both directions.

LoRa Alliance The LoRa Alliance is an open, non-profit organization led by Semtech in March 2015. Its founding members include French Actility, Chinese AUGTEK and Royal Dutch Telecom kpn. In less than a year, the alliance has developed more than 150 member companies, including many heavyweight manufacturers such as IBM, Cisco, and Orange of France. There are a large number of companies in each link of the industrial chain (terminal hardware manufacturers, chip manufacturers, module gateway manufacturers, software manufacturers, system integrators, network operators). The openness of this technology makes competition and cooperation more difficult. The adequacy has promoted the rapid development and ecological prosperity of LoRa.

LoRa technical features

(1) Sensitivity -148dBm, communication distance >15km;

(2) Minimal infrastructure costs, using gateways/concentrators to expand system capacity

(3) Battery life >5 years, receiving current 10mA, sleep current <200nA

(4) License-free frequency band, low cost for nodes/terminals

LoRa technology advantages

(1) Long distance, transmission distance can reach 8km, wide area

(2) Easy to build and deploy, it can be installed and used in most places.

(3) Low power consumption and long battery life

(4) Low power consumption and long battery life. The price of LoRa terminal is around 100-200.

LoRa technical disadvantages

(1) Spectrum interference: With the increase in LoRa devices and networks, spectrum interference exists between them.

(2) The network needs to be newly built

(3) Technology is too concentrated: LoRa technology is too concentrated in Semtech, which is not conducive to the development of the industry

[Extended] LoRaWAN protocol

LoRaWAN is a Low Power Wide Area Network (LPWAN) standard based on the open source MAC layer protocol launched by the LoRa Alliance. This technology can provide local, national or global networks for battery-powered wireless devices. LoRaWAN targets some core needs in the Internet of Things, such as secure two-way communication, mobile communication and static location identification services. This technology enables seamless interoperability between smart devices without the need for complex local configuration, giving users, developers and enterprises in the IoT field free operating rights.

The LoRaWAN network architecture is a typical star topology. In this network architecture, the LoRa gateway is a transparent transmission relay that connects the terminal device and the back-end central server. The gateway and server are connected through standard IP, and the terminal device uses a single hop to communicate with one or more gateways. There is two-way communication between all nodes and gateways, and operations such as cloud upgrades are also supported to reduce cloud communication time.

Communication between the terminal and the gateway is completed based on different frequencies and data transmission rates. The selection of data rate requires a trade-off between transmission distance and message delay. Due to the use of spread spectrum technology, communications with different transmission rates will not interfere with each other, and a set of “virtualized” frequency bands will be created to increase gateway capacity. The data transmission rate of LoRaWAN ranges from 0.3 kbps to 37.5 kbps. In order to maximize the battery life of the terminal device and the entire network capacity, the LoRaWAN network server controls the data transmission rate and each time through an adaptive data rate (ADR) scheme. The radio frequency output power of a terminal device. The wide-area network with nationwide coverage targets IoT applications such as critical infrastructure construction, confidential personal data transmission or social public services. Regarding secure communication, LoRaWAN generally uses multi-layer encryption to solve the problem: 1. Unique network key (EU164) to ensure network layer security; 2. Unique application key (EU164) to ensure application layer terminal-to-terminal communication. security; 3. The special key (EUI128) belonging to the device. The LoRaWAN network divides terminal equipment into three categories: A/B/C according to different actual applications: Class A: two-way communication terminal equipment. This type of terminal device allows two-way communication, and each terminal device’s upstream transmission is accompanied by two downstream reception windows. The end device’s transmission slot is based on its own communication needs, and its fine-tuning is based on a random time base (ALOHA protocol). Terminal equipment belonging to Class A has the lowest power consumption during application. After the terminal sends an uplink transmission signal, the server can quickly perform downlink communication. At any time, the server’s downlink communication can only follow the uplink communication.

Typical applications of Lora

Smart oil field

Smart oilfields use various online, real-time measurement sensing devices, such as various instruments and other information sensing devices installed on oil and gas wells, pipelines, oil and gas processing, processing, storage and transportation equipment, to connect to the enterprise network or Internet, a network for information exchange and communication to achieve intelligent identification, positioning, tracking, monitoring and management

Logistics tracking

An important requirement for tracking or positioning the market is the battery life of the terminal. Logistics tracking can serve as a practical example of hybrid deployment. Logistics companies can deploy networks at required locations according to positioning needs, which can be in warehouses or transport vehicles. At this time, portable base stations come in handy. LoRa can provide such a deployment solution. At the same time, LoRa has a characteristic that communication is relatively more stable when moving at high speeds. LoRa is more suitable for logistics tracking.

Smart water

Smart water affairs senses the operating status of urban water supply and drainage systems in real time through online monitoring equipment such as digital loggers, wireless networks, and water quality and pressure gauges, and uses a visual method to organically integrate water management departments and water supply and drainage facilities to form the “Urban Water Affairs Internet of Things” , and can conduct timely analysis and processing of massive water affairs information, and make corresponding processing results to assist decision-making and suggestions, and manage the entire production, management and service process of the water affairs system in a more refined and dynamic way, thereby achieving a “smart” state .

Smart agriculture

For agriculture, low-power and low-cost sensors are urgently needed. The application of sensors such as temperature and humidity, carbon dioxide, and salinity is of great significance to increasing agricultural yields and reducing water consumption. These sensors need to upload data regularly. LoRa is very suitable for such scenarios.

Intelligent Building

For the renovation of buildings, sensors such as temperature and humidity, safety, harmful gas, and water flow monitoring are added and the monitoring information is uploaded regularly, which facilitates the supervision of managers and makes it more convenient for users. Generally speaking, the communication of these sensors does not need to be particularly frequent or to ensure particularly good service quality, and a portable home gateway can meet the needs. Therefore, LoRa is a more suitable choice in this scenario.