Popular Science: What is LPWA?
Latest update time：2021-08-31 02:07
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Definition of LPWA
LPWA – Low power wide area, short for low power 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 can reach 160dBm, while BLE and Zigbee are generally below 100dBm.
Compared with traditional cellular network technologies (2G, 3G), LPWA has lower power consumption and battery-powered devices can have a service life of up to several years.
Based on these two significant 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.
LPWAN network connection can be in various forms. The typical topology is shown in Figure 1. Taking data uplink as an example, the wireless terminal sends a data signal, the base station or gateway receives and transmits the data to the cloud platform, and the cloud platform distributes the data to the corresponding client server according to the device ID.
For private LPWAN networks, the cloud and client server can be integrated.
Figure 1 Typical LPWA network connection
Characteristics of LPWA
LPWA has the following technical features to meet the needs of IoT applications:
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Low power consumption
General IoT devices cannot be powered directly by a power source, so battery life becomes the primary consideration. LPWA optimizes technology to enable battery-powered devices to be used for several years.
For example, terminal devices using Sigfox technology can be powered by AA batteries for about 10 years.
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Long distance
For indoor or short-distance IoT applications, low-power Bluetooth, Zigbee and other wireless technologies can be used. LPWA is aimed at outdoor or long-distance wireless connection needs, and the transmission rate requirement is lower, so the transmission distance is longer, at least at the kilometer level.
Sigfox uses ultra-narrow band for data transmission and selects 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 tens of kilometers.
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low cost
The popularization of new technologies is inseparable from the continuous reduction of costs. Lower costs can enable the application of technologies in more fields, especially price-sensitive applications.
With the improvement of technology maturity, the popularization of applications, and the increase in the number of device connections, the general price of RF modules used in LPWA terminal devices is expected to be below US$5.
Sigfox technology has already reached full commercial maturity a long time ago, and the price of its terminal modules can even reach US$2, which plays an important role in the popularization of technology.
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High capacity
The primary connection object of traditional wireless cellular networks is people, while the connection object of the Internet of Things is objects, and the number of objects will certainly far exceed the number of people, which requires LPWA networks to have a larger capacity to avoid network congestion and interference between devices.
A single base station in the Sigfox network can process millions of device messages every day, and can receive and process nearly 300 messages at the same time, with a packet loss rate of only 0.5%, ensuring a high network quality of service (QoS).
In addition to the above significant technical features, LPWA usually also has the characteristics of low speed and high latency.
Figure 2 Comparison of LPWA technology characteristics
LPWA Application Scenarios
LPWA technology can be used in many IoT application scenarios to realize the digitization and intelligence of industries, thereby further improving efficiency and saving costs, and promoting the improvement of labor productivity in the entire society.
Its typical application scenarios are:
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Logistics positioning and tracking – real-time reporting of logistics location and status information
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Asset management – asset location, inventory status reporting
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Smart meter reading – reporting of meter numbers and status
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Smart city – lighting, transportation, intelligent infrastructure detection, smart parking, etc.
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Smart agriculture – livestock tracking management, soil testing, smart irrigation, etc.
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Environment/Public – Disaster detection, smoke detection, air pollution, equipment status, elderly care, etc.
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Smart home – smart home appliances, home security systems, status detection and reporting, etc.
Typical LPWA technologies
According to the nature of the use of wireless spectrum, LPWA can be divided into two types of technologies: licensed frequency bands and public frequency bands.
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Typical public frequency bands include Sigfox and LoRa, which use the public ISM frequency band and do not need to pay spectrum fees. However, the government still regulates the use of the spectrum to ensure that different technologies can be compatible with each other, such as BLE and Wifi.
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The licensed frequency band is Cellular-IoT (C-IoT for short) technology, which uses specific dedicated wireless frequency bands authorized by the government and requires payment of spectrum fees. Traditional telecom operators are the main body of network deployment and operation. The technical specifications are based on cellular network technology and are dominated by 3GPP.
Sigfox
Sigfox technology was designed and developed by the French company of the same name. Founded in 2010, it is one of the earliest established LPWA players with the highest technical maturity. As of 2019, it has been commercialized in more than 60 countries around the world.
Sigfox uses 100Hz ultra-narrowband spectrum in the public frequency band to modulate and transmit data messages, so it has a higher power density per unit frequency band and stronger anti-interference ability, making it suitable for data transmission using the public frequency band.
Sigfox provides complete network solutions, including base stations and the cloud. It seeks and relies on local partners to deploy and operate networks around the world. Sigfox provides network equipment and technical support services.
The terminal equipment is an open ecosystem. Any RF module or chip that supports the Sigfox protocol can connect to the Sigfox network. For terminal equipment manufacturers, there is more room for choice and more favorable price options.
Relying on a strong global ecosystem, Sigfox users can get an end-to-end (terminal to cloud) overall solution, so that their products can be quickly connected to the Sigfox network and brought to market.
Because the Sigfox network is deployed globally by Sigfox, it can ensure the uniformity and stability of network service quality to the greatest extent. That is, with one network around the world, user devices can enjoy cross-border convenience without the need for roaming services, while being able to connect to networks of the same quality. This is especially attractive for applications such as logistics or cross-border operations.
LoRa
LoRa is a proprietary technology of the American company Semtech. It is actually a wireless modulation and demodulation technology that uses a spread spectrum solution.
Semtech acquired the IP property rights of LoRa through the merger of France's Cycleo in 2012, and used it to design, manufacture and market radio frequency chips. It is a pure semiconductor company and has a monopoly on the supply of LoRa chips.
Although Semtech currently also licenses a small amount of LoRa IP, such as Alibaba in China, the IP is proprietary to Semtech. No company can design and manufacture LoRa chips without authorization, so customers have little choice.
LoRa also uses public frequency bands for radio frequency signal transmission. The upper layer protocols and specifications are defined by LoRaWan, and the LoRa Alliance is responsible for publishing and maintaining them.
Anyone can buy LoRa chips or modules to design LoRa terminals and gateway devices, or design or buy equipment to build LoRa networks. Therefore, most LoRa networks are currently small-area and private, and there are few nationwide general IoT networks. Compatibility between devices and networks is also a big challenge.
LoRa achieves high sensitivity through spread spectrum technology, enabling long-distance transmission, but the network capacity is limited and cannot efficiently achieve parallel reception and processing of large amounts of device information, which is a huge challenge for large-scale or nationwide deployment.
Cellular-IoT
The current mainstream Cellular-IoT (C-IoT) technologies refer to NB-IoT and LTE-M, both of which are based on traditional cellular network technologies and are tailored and optimized for low-cost and low-power applications in the Internet of Things.
The technical specifications are defined and distributed by 3GPP, based on proprietary licensed spectrum, and deployed and operated by traditional telecom operators.
Because C-IoT is based on traditional cellular network technology, it has higher technical complexity and corresponding cost and power consumption than new LPWA customized technologies such as Sigfox. Similar to 3G/4G, C-IoT terminal devices also need to connect and attach to base stations, perform protocol handshakes and configure network parameters, while Sigfox terminal devices have no dependencies on base stations, are more autonomous, and have controllable power consumption.
In addition, because of its attachment to base stations, NB-IoT is actually only suitable for application scenarios where the device is fixed in position.
From a global perspective, C-IoT networks are decentralized. Each operator can only deploy and operate in the country or region where they are located. The parameter configuration and service quality of different networks are different.
Taking the NB-IoT network as an example, there are more than ten frequency bands supported in total. Networks in different countries or regions can use different bands, which is a higher cost and technical challenge for terminal devices.
The service quality of different networks cannot be unified and guaranteed. Switching between networks also requires high roaming fees. NB-IoT networks do not even support roaming.
Source: Sigfox
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