【物联网通信技术】——LoRa-海南世电科技

summarize

Low Power Wide Area Network (LPWAN) is an integral part of the Internet of Things (IoT), featuring low power consumption, wide coverage, and strong penetration, and is suitable for application situations where a small amount of data is sent and received every few minutes, such as smart water metering, street light monitoring, smart parking andintelligent firefighting (psychology)Wait a minute, Chinese carriers are pushingNB-IoTtechnology, LoRa technology,SigFoxtechnology, eMTC technology all belong to the technology of wide area network. Among them, eMTC and NB-IoT are carrier-licensed bands; the bands for LoRa and SigFox technologies belong to unlicensed bands

LoRa is based onSemtechA low power consumption LAN developed by the companywireless standard, which aims to solve the contradictory problem of power consumption and transmission difficult to cover the distance. In general, low power consumption is close to the transmission distance, high power consumption is far from the transmission distance, through the development of LoRa technology, to solve the technical problems in the same power consumption conditions than other wireless methods to spread the distance, to achieve the unity of the low power consumption and long distance.LoRa from a small wireless technology to the current Internet of Things field communication of a kind of standard, every year with a double-digit terminal growth rate to get industry Its low power consumption, long-distance transmission and more node capacity make LoRa come into more and more use scenarios.

lora的频谱特点 — Image fromSemtechofficial website

LoRa adopts a star network, users can realize flexible networking through mesh, point-to-point or star network protocols and architecture; LoRa physical layer wireless modulation technology, belongs to the linear modulation spread spectrum technology (Chirp Spread Spectrum, CSS), also known as broadband linear frequency modulation (Chirp Modulation) technology. A technology that trades bandwidth for sensitivity, maximizing sensitivity allows signals to travel farther, which is the basis for the technology's rapid growth.In 2019, users in Spain used LoRa technology to transmit signals in a hot air balloon for over700 kilometers.The

lora传输700公里 — Image from LoRa Developer Portal

There are foreign companies installing LoRa to near-Earth satellites (600km-1600km) and receiving relevant signals from the satellites

LoRa History

LoRa is an abbreviation for Long Range, which means long distance transmission. The basic explanation is similar to the commonly used FSK or QAM and other frequency modulation technology, is a linear frequency modulation and spreading of the physical layer of the modulation technology, the broader meaning is a similar to thebluetooth(math.) genusWIFIand interface systems and protocols for communication such as NB-IoT.

French startup Cycleo first developed a linear FM spread spectrum modulation technology, in 2012 Semetech acquired Cycleo; this technology was applied to the chip, and named LoRa; after that Semetech developed a complete set of chips based on LoRa technology, including gateways (1301 series) and terminals (126 series, 128 series) to be used Semetech has also developed a complete set of chips for gateways (1301 series) and terminals (126 series, 128 series) based on LoRa technology.

In 2015 Semetech joined forces with Cisco, IBM and a number of vendors to create the LoRa Alliance and then launched the LoRaWAN specification, which now has more than 500 members globally (Tencent, Alibaba, Intel, etc.), more than 100 telecom carriers (carriers in South Korea, Japan, and Europe), and more than 100 million endpoints are already being set up and used

LoRa technology features

Modulation: Spread Spectrum, a proprietary technology owned by Semetech.
Transmission distance: the highest sensitivity can reach -149.1dBm; ZigBee and Bluetooth and other technologies in the -100dBm sensitivity; that is to say, it can accept 100,000 times smaller than the ZigBee signal, so the transmission distance of the LoRa can be done very far, in general, the suburbs can be up to about 50 kilometers.
Anti-interference ability: LoRa has the limit of communication technology just interference ability, 25dB below the noise can still receive the signal
Operating frequency: ISM's band, LoRa uses free bands around the world, including 433MHz, 470MHz (China), 868MHz (Europe), 915MHz (USA) and other unlicensed bands in different countries (SM bands)
Technical Standards: IEEE 802.15.4g, LoRaWAN
Device capacity: the number of nodes that can be connected to the gateway can be in the thousands, depending on the frequency of packet sending
Independent network: similar to Wi-Fi technology, on-demand network deployment, the whole system does not need the support of the operator, private individuals, enterprises, buildings and parks can be based on their own needs to establish their own private network, the whole system is lightweight
Low Power Consumption: LoRa does not require a lot of power to transmit over long distances due to its good sensitivity, its sleep current is 1uA, and its receive current is 4mA. it has the function of detecting channel activity, which can wake up the product in a very short process. Therefore, LoRa products can be easily used for up to 10 years under battery usage.
Secure encryption: AES128 encryption
Transmission speed: 18b/s to 40kb/s
Anti-frequency deviation and Doppler effect: The signal is received with severe distortion of the waveform due to multipath phenomenon or wrap-around phenomenon, and LoRa can efficiently resolve the demodulated signal correctly. Since LoRa has better anti-Doppler effect, LoRa has good characteristics in high speed moving devices.
LoRa with localization and ranging performance

LoRa Application Areas

LoRa's technical characteristics determine its application field is very wide, its biggest drawback is that the transmission bandwidth is relatively narrow, but it is very suitable for the Internet of things in a variety of scenarios, especially the cellular network is not good and more stringent requirements on power consumption is very suitable for the LoRa scenarios.

More than 70 countries around the world have deployed LoRa networks to operate the IoT
Operators of more than 100 wide-area networks
More than 100 million LoRa end products already available

There are roughly the following scenarios for applying LoRa to end products

Smart meter reading, mainly for water meters, gives LoRa a big advantage in water meters due to the long standby time and operation required
Smart agriculture, due to being in the field, cannot be met by carrier networks, plus power consumption and cost lead to clear advantages of LoRa
Intelligent buildings, LoRa-based localized coverage, face annual fees, making LoRa an option for some users
Smart Cities and Smart Parking, geomagnetic-like sensors are buried in the ground and need to work for a long time, so LoRa is recognized for its power consumption
Environmental monitoring, smart homes, smart transportation, regional tracking and location of assets and people.