Preface
Hello everyone, I am Mr. Lin, The Internet of Things is developing too fast now, and the number of applications in the field is increasing. The future direction of intelligent development is the Internet of Things. So there are some application technologies in the Internet of Things that we need to understand.
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LPWA definition
LPWA – Low power wide area, the abbreviation of low power consumption wide area technology, uses lower power consumption to achieve long-distance wireless signal transmission. Compared with familiar technologies such as low-power Bluetooth (BLE), Zigbee and Wifi, LPWA has a longer transmission distance, generally at the kilometer level, and its link budget (link budget) can reach 160dBm, while BLE and Zigbee are generally below 100dBm. Compared with traditional cellular network technologies (2G and 3G), LPWA consumes less power and battery-powered devices can last for several years. Based on these two prominent features, LPWA can truly enable the interconnection of things and help and lead the Internet of Things (IoT) revolution.
LPWAN – Low power wide area network, a wireless connection network built using LPWA technology. The network connection forms of LPWAN can be diverse. The typical topology is shown in Figure 1. Taking data upload as an example, a wireless terminal sends data signals, a base station or gateway receives and transmits data to the cloud platform. The cloud platform distributes data to the corresponding client server according to the device ID. For private LPWAN networks, the cloud and client servers can be integrated.
Figure 1 Typical LPWA network connection
LPWA characteristics
LPWA In response to the needs of IoT applications, it has the following technical characteristics: ○ low power consumption
General IoT devices cannot directly use power supply, and the battery life becomes the primary consideration. LPWA has technically optimized this, so that battery powered equipment can be used for several years. For example, terminal devices using Sigfox technology can be powered by AA battery for about 10 years.
○ Long-distance
Indoor or short-distance IoT applications can use wireless technologies such as low-power Bluetooth, Zigbee, etc. LPWA is aimed at outdoor or long-distance wireless connection needs, and the transmission rate requirements are low, so the transmission distance is longer, at least at the km level. Sigfox uses ultra-narrow band for data transmission and chooses a lower transmission rate, so that the link budget between the device and the base station can reach 160dBm, and the signal transmission distance in open areas can reach dozens of kilometers.
○ low cost
The popularization of new technologies is inseparable from the continuous reduction of costs. Lower costs can enable the technology to be applied in more fields, especially price-sensitive applications. The RF module used in LPWA terminal equipment is generally expected to be under $5 as the technology matures, popularizes applications, and increases the number of equipment connections. Sigfox technology has already reached commercial maturity for a long time, and its terminal module price can even reach US$2, which plays an important role in the popularization of technology.
○ Large capacity
The primary connection object of traditional wireless cellular network is people, and the connection object of the Internet of Things is objects, and the number of objects will definitely far exceed the number of people. This requires the LPWA network to have a larger capacity to avoid network congestion and interference between devices. A single base station in Sigfox network can process millions of device messages every day, and can receive and process nearly 300 messages at the same time, while the packet loss rate is only 0.5%, ensuring a high quality of network service (QoS). In addition to the above significant technical features,
LPWA usually has low speed, high latency and other characteristics.
Figure 2 Comparison of LPWA technology characteristics
LPWA application scenario
LPWA technology can be used in many IoT application scenarios to realize the digitalization and intelligence of the industry, thereby further improving efficiency and saving costs, and promoting the improvement of labor productivity of the entire .
Its typical application scenarios are:
◇ Logistics positioning and tracking – real-time reporting of logistics location and status information
◇ Asset management – asset positioning, inventory status reporting
◇ Intelligent meter reading – instrument numbers and status reporting
◇ Smart city – lighting, transportation, basic implementation detection intelligent, intelligent parking, etc.
◇ Smart city – lighting, transportation, intelligent implementation detection, smart parking, etc.
◇ ◇ Smart city – lighting, transportation, intelligent implementation detection, smart parking, etc.
◇ ◇ Smart agriculture – livestock tracking and management, soil detection, smart irrigation, etc.
◇ Environment/public – disaster detection, smoke sensing, air pollution, equipment status, elderly care, etc.
◇ Smart home – smart home appliances, home security systems, status detection reporting, etc.
Typical LPWA technology
According to the nature of the use of wireless spectrum, LPWA can be divided into two types of technologies: licensed frequency band and public frequency band.
▶ Typical public frequency bands are Sigfox and LoRa. They use public ISM bands and do not need to pay spectrum fees. However, there are still governments to regulate the use of spectrum to ensure that different technologies can be compatible with each other, such as BLE and Wifi.
▶ The licensed frequency band is Cellular-IoT (C-IoT for short) technology. Using specific dedicated wireless frequency bands authorized by the government, spectrum fees are required. Traditional telecom operators mainly deploy and operate the network. The technical specifications are based on cellular network technology and are distributed mainly by 3GPP.
Sigfox
Sigfox technology was designed and developed by the French Sigfox company of the same name. It was established in 2010. It is the earliest veteran LPWA player with the highest technological maturity. As of 2019, it has been commercially operated in more than 60 countries around the world. Sigfox uses 100Hz ultra-narrowband spectrum modulation and transmits data messages in the public frequency band, so it has a higher power density in the unit frequency band and has stronger anti-interference ability. It is suitable for data transmission using the public frequency band.
Sigfox provides complete network solutions, including base stations and cloud, seeking and relying on local partners to carry out network deployment and operations around the world, and Sigfox provides network equipment and technical support services. Terminal devices are an open ecosystem. Any RF module or chip that supports the Sigfox protocol can be connected to Sigfox network. For terminal device manufacturers, there are more room for choice and more preferential price options. Relying on a strong global ecosystem, Sigfox users can get an end-to-end (end-to-cloud) overall solution that enables their products to quickly connect to the Sigfox network and launch them to the market.
Because Sigfox network is led by Sigfox company, it can ensure the unity and stability of network service quality to the greatest extent. That is, with a global network, user equipment can enjoy cross-border convenience, without roaming services, and can be connected to networks of the same quality, which is particularly attractive for applications such as logistics or cross-border operation.
LoRa
LoRa is a proprietary technology of Semtech, the United States, and is actually a wireless modem and demodulation technology that adopts spread spectrum scheme. Semtech obtained the IP ownership of LoRa through the acquisition of French Cycleo in 2012, thereby designing and manufacturing RF chips and selling them for market sales. It is a pure semiconductor company that monopolizes the supply of LoRa chips. Although Semtech also authorizes a small amount of LoRa IP, such as domestic Alibaba , IP is proprietary to Semtech. Without authorization, no company cannot design and manufacture LoRa chips, so customers have very little choice.
LoRa also uses the public frequency band for radio frequency signal transmission. The upper layer protocol and specifications are defined by LoRaWan, and the LoRa Alliance is responsible for publishing and maintaining. Anyone can purchase LoRa chips or modules to design LoRa terminals and gateway devices, or design or purchase equipment to build LoRa networks. Therefore, most LoRa networks are small regions and private, and there are few national general IoT networks, and compatibility between devices and networks is also a big challenge.
LoRa achieves high sensitivity through spread spectrum technology , so that it can perform long-distance transmission, but the network capacity is limited and it is impossible to efficiently realize parallel reception and processing of large-scale equipment information, which is a huge challenge for large-scale or nationwide deployment.
Cellular-IoTh
The current mainstream Cellular-IoT (C-IoT) technology refers to NB-IoT and LTE-M. They are both based on the traditional cellular network technology, and are cropped and optimized for low-cost and low-power applications of the Internet of Things. Technical specifications are defined and distributed by 3GPP, based on proprietary licensed spectrum, and are deployed and operated by traditional telecom operators.
Because C-IoT is based on traditional cellular network technology, compared with brand-new LPWA customization technologies such as Sigfox, the technical complexity and corresponding cost and power consumption will be higher. Similar to 3G/4G, C-IoT terminal devices also need to connect and attach to the base station, protocol handshake and network parameter configuration, while Sigfox terminal devices and base stations have no dependencies, are more autonomous, and have controllable power consumption. In addition, due to the attachment to the base station, NB-IoTh is actually only suitable for application scenarios where the device is fixed.
Globally, the C-IoT network is decentralized, and each operator can only deploy and operate in the local country or region, and the parameter configuration and service quality of different networks vary. Taking NB-IoT network as an example, there are more than ten frequency bands (Bands) supported in total, and networks in different countries or regions can use unused bands, which is a higher cost and technical challenge for terminal devices. The service quality of different networks cannot be unified and guaranteed, and switching between networks also requires high roaming costs. NB-IoT networks do not even support roaming.
