With the rapid development of Internet of things (IoT) technology, a large number of IoT scenarios have been developed, and various IoT communication systems have been launched one after another. These IoT communication systems include narrow-band Internet of things (NB IoT), lte-m (long term evolution, category M1), wi sun and sigfox. These systems have various technologies and promotion alliances competing with each other in the market. Lora technology is also an Internet of things communication technology, which is also laying out and building a global Internet of things system.
Introduction to LoRa
Lpwan (low power wide area network) is a kind of Internet of things network layer technology facing the requirements of long-distance and low power consumption in the Internet of things. Lpwan has the characteristics of low power consumption, long distance, low broadband, simple network structure and low operation cost. As one of the mainstream technologies in lpwan, Lora has a more mature ecological chain and a faster pace of business. It is expected to maintain a doubling rate in the next few years.
There are two main types of wireless technologies in IoT applications. One is short-range wireless technology, such as Bluetooth/WiFi/ZigBee. The other is the technology that forms the wide area network, such as 2G/3G/4G. The advantages and disadvantages of each technology are very obvious. Before the emergence of LPWAN technology, usually long-distance and low-power consumption can only choose one. After the emergence of LPWAN technology, the problems of fish and bear’s paws can be described as balanced. In addition to achieving longer-distance communication and ultra-low power consumption, it can also save additional repeater costs.
LoRa is one of the mainstream technologies in LPWAN communication technology. It is an ultra-long-distance wireless transmission scheme based on frequency modulation spread spectrum technology. LoRa was first launched by Cycleo in France and was acquired by Semtech in 2012. The LoRa transmission scheme takes into account both distance and power consumption, and provides users with a sensor network with long battery life, long transmission distance, and simple networking. The network frequency bands transmitted by LoRa are basically free frequency bands in the world. These frequency bands are 433HZ, 868HZ, 915HZ, etc.
What are the advantages of LoRa?
Improved receiving sensitivity and reduced power consumption.
The bandwidth of Lora transmission channel is 157db, and the theoretical transmission distance is up to 15km. The working current of Lora is only 10mA and the standby current is 200na. The working power consumption is very low, which greatly increases the service life of the battery.
Lora gateway / several processors support high-speed parallel processing of multi-channel and multi data, and the system capacity is large.
Gateway is the bridge between each network node and independent IP. The gateway connects IP with network nodes through communication network. Lora gateway supports parallel processing and has large system capacity. It can handle 5 million network communications between nodes every day. Lora gateway has high transmission efficiency. Assuming 5 million transmissions per day, each transmission size is 10bytes, and its network occupancy rate is only 10%. The Lora gateway is installed in the accessories of the mobile communication base station. Now the transmission power of the base station is about 20dbm. In the environment with many buildings, the network communication of the Lora gateway can cover about 2km. In the area with low building density, the network coverage of the Lora gateway can reach 10km.
Lora terminal and gateway communication support ranging and positioning
Lora’s method of testing distance and position is different from rssirsi (received signal sterngth indication). Lora’s distance measurement method is determined based on the time of signal transmission in the air, while Lora’s positioning method is measured according to the signal transmission time difference of multiple gateways to a node, and the positioning accuracy within 10km is up to 3m.
What is the network architecture of LoRa?
Lora network is mainly composed of application server, network server, gateway and terminal (including Lora module), which supports two-way data transmission. Lora’s network architecture is a star topology. Lora gateway plays a role of signal transmission relay in this network architecture, connecting terminal equipment on one side and network server on the other. The terminal device can transmit signals to another terminal or server through one or more gateways.
LoRa terminal equipment
The terminal nodes of Lora are various Internet of things devices, such as smart meter reading, smart meter, express tracker, ranch manager, etc. The Lora module in these devices is connected with the Lora gateway through the wireless communication network, and the Lora gateway is connected to the server through Ethernet or other communication networks to realize the interconnection between the terminal and the server. The communication between Lora gateway and network server is through TCP / IP protocol.
According to Lora data transmission, Lora terminal equipment is divided into three categories: Class A, class B and class C.
Lora class Aterminal equipment
After sending a message, the node will open an rx1 window 1 s after the default. The data rate and frequency of the receiving window are the same as the uplink data. If the message is a confirm message and rx1 does not receive the corresponding downlink, the node will open another receiving window rx2 1 s + 1 s after sending the message, The data rate and frequency point of the receiving window have different default data for different frequency bands in lorawan protocol. The following are the characteristics of Lora class a terminal equipment:
- frames are usually divided into uplink transmission and downlink transmission. The uplink route consists of 1 time slot and 2 downlink time slots (or windows).
- the terminal equipment shall be arranged by the terminal equipment as required. It is randomly determined, similar to ALOHA protocol.
- it is the lowest power consumption Lora terminal device.
Lora class B terminal equipment
Class B will open a receiving window at intervals based on the receiving window of class A. The following are the functions of Lora class B terminal equipment:
- in addition to the two time slots specified in class A, such terminal equipment uses additional reception windows during downlink.
- class B equipment will receive additional reception windows for the specified duration.
- the duration is specified by the gateway using the beacon frame.
- therefore, in this way, the Lora system indicates to the server when the terminal device can listen.
Lora class C terminal equipment
Based on the class a receiving window, the receiving window of class C is open at all times except the node sending time.
Class a must be implemented by nodes accessing Lora network. Both class B and class C are implemented by adding functions based on class A. class B is applicable to the positioning of mobile nodes. Class C node is applicable to the case where the control command is actively issued and the power supply is sufficient. Lorawan1.1 protocol optimizes class B and network access. The following are the functions of Lora class C terminal equipment:
- such terminal equipment can listen all the time except for transmission mode. Therefore, it is very suitable for applications requiring more downlink transmission.
- class C Lora terminals will use more power than their class A and B counterparts.
- the latency is the lowest among all Lora class terminal devices for data communication between servers and terminal devices.
LoRa application scenarios
The LoRaWAN-based network can provide secure data transmission distance and two-way communication, and cover urban areas with the least network infrastructure. LoRa will be widely used in a variety of application scenarios such as smart agriculture, smart buildings, and smart logistics.
For farms, there is a large market for low-power, long-distance and long-life sensors. Detecting the temperature, humidity, carbon dioxide concentration, pH and other data obtained by the sensor in the crop growth environment is of great significance to improve crop yield and reduce resource waste. These data do not have high requirements for time delay. Lora is the best choice. The sensor can transmit the collected data to the background through Lora, Farmers can judge whether to spray water and fertilize according to the data.
Pasture farming has a great demand for low-power and long-distance tracking tools. At present, the number of cattle or sheep grazing on the grassland is generally very large. It is difficult for ranchers to observe the number and health of these animals one by one. They can judge whether the grazing animals are within the range of the pasture through the tracker. They can sense the heartbeat and body temperature of the animals through the sensor, and transmit the data to the background for centralized processing through Lora.
After the completion of building decoration, the temperature, humidity, formaldehyde and other harmful gas content, light detection and other data of the building are very important to users. The feedback of these information is conducive to users’ regulation of the indoor environment and make users have a healthier and comfortable indoor environment. Generally speaking, the indoor environment does not change very much. There is no need to obtain the indoor environment information in real time, and the communication requirements are not high. In this scenario, a simple home gateway can meet these needs. In this scenario, Lora is a very good choice.
In the automated industrial production environment, a large number of intelligent technologies are applied, and various information and data are converged in the network. Therefore, the characteristics of the selected network are directly related to the execution quality of the production plan. By analyzing these data, producers can estimate the production efficiency and analyze the production process, which can quickly solve the problems encountered in production. In this scenario, the cost and service life of network transmission tools are very high, and Lora is a very suitable choice.
The geographical scope of the logistics industry is very broad, so the first choice when choosing a network is low investment and long working life. In order to be able to track the pallets and determine the location and status of the goods, what the freight company needs is that the facilities involved in the entire logistics process are under the network coverage, so not only the network nodes are required to be economical enough for large-scale installation, but also have the flexibility to make it It can be installed on a transportation vehicle as a mobile gateway. In this way, the NB-IoT technology that needs to rely on 4G base stations to deploy the network obviously cannot meet this requirement, and the low cost of LoRa, high battery life, high mobility, and the stability of communication during high-speed movement make it unique in the field of intelligent logistics. Lead the way.
In the new wave of development of the Internet of Things, in the field of low-power wide-area networks, developed markets have already deployed applications on a large scale, and domestic participants have also used open wisdom to promote the large-scale deployment and deployment of LoRa networks in China. Application, I believe that with the increase of industry applications, this domestic carrier-level LoRa network formed with the concept of sharing economy will also become the core area of the global LoRa layout.
At present, the world’s two major Internet of Things networks, NB-IoT and LoRa, are developing rapidly. According to statistics from relevant departments, more than 1,000 Internet of Things application products have landed in various provinces all over the world. It is reported that 70% of enterprises are actively seeking mature, reliable and fast-growing IoT products. Most companies purchase NB-IoT and LoRa IoT solutions from MOKOLora. The purchases include LoRa gateways, smoke detectors, and water Dozens of IoT products such as monitoring, infrared detection, positioning, power sockets, etc., and the development of NB-IoT and LoRa IoT products on behalf of the company, in order to quickly enclose the Internet of Things business and rank among the leading Internet of things in cities across the world. “The development of the world Internet of Things sees MOKOLora” situation is gradually taking shape.
Low Power Wide Area Network (LPWAN) is an indispensable part of the Internet of Things. It has flexible and expandable characteristics and can be large or small in scale. This is required for the growth and exploration stage of the Internet of Things industry. Said to be the most suitable technology for the Internet of Things. LoRa is safe and reliable, with features such as two-way authentication, end-to-end encryption, and integrity protection. It is comprehensive and forward-looking in security design, but the security of the Internet of Things cannot be ignored, and the industry needs to work together and continue to promote it.