With the rapid development of the Internet of Things, a variety of LPWAN technologies have appeared on the market. This article summarizes the seven connection technologies, let's take a look!
This article includes the definition of a low-power WAN and the advantages of LPWAN technology over other IoT connectivity technologies. In this article, we will describe in more detail the differences between the various LPWANs in the field of Internet of Things.
In the end, you'll learn if LPWAN is right for your IoT application, and if so, how best to advance your project.
There are a variety of LPWAN technologies and standards on the market, and we will focus on SigFox, LoRa, RPMA, Symphony Link and Weightless, as these technologies are the most active in development and application. Some other proprietary protocol stacks, such as the Dash7 Alliance protocol, will not be covered in this article because of their low focus.
Next we will outline these several LPWAN technologies separately.
SigFoxFounded in 2009, SigFox is a French company based in Labège, France. The promotion of SigFox in Europe has been very successful and can be said to be the most attractive (or at least the most recognizable) in the LPWAN field. It also has a great supplier ecosystem, including Texas Instruments, Silicon Labs and Axom.
SigFox uses proprietary technology to achieve longer transmission ranges with lower modulation rates. Based on this design, SigFox is a good choice for applications that only need to send small, unusual bursts of data.
Typical applications for SifFox include parking sensors, water meters or smart trash cans. Of course, it also has some drawbacks. Sending data back to the sensor, the device (downlink capability) is severely limited, and signal interference can be a problem.
LoRaThe LoRa Alliance is an open, non-profit organization that promotes and promotes the ecosystem of LPWAN technologies. It has approximately 400 member companies in North America, Europe, Africa and Asia, and its founding members include IBM, MicroChip, Cisco, Semtech, Bouygues Telecom, Singtel, KPN, Swisscom, Fastnet and Belgacom.
LoRaWAN is an open standard network layer protocol managed by the LoRa Alliance. However, it is not really open, because the underlying chips that implement a complete LoRaWAN protocol stack are only available through Semtech. Specifically, LoRa is the physical layer, which is the chip. LoRaWAN is the MAC layer, the software on the chip, to achieve network connectivity.
Its function is similar to SigFox because it is mainly used for uplink-only applications (data from sensors, devices to gateways) for multiple terminals. Instead of using narrowband transmissions, it uses coded messages to extend the information of different frequency channels and data rates. These messages reduce conflict and interference, which increases the capacity of the gateway.
RPMARandom Phase Multiple Access (RPMA) is a proprietary LPWAN technology stack developed by Ingenu. Founded in 2008 in San Diego, California, the company was formed by former Qualcomm engineers and was originally called On-Ramp Wireless.
As a founding member of the IEEE 802.15.4k task group dedicated to low-power device monitoring, Ingenu has made tremendous efforts to develop RPMA, while SigFox and LoRaWAN Group are focused on accelerating time to market.
RPMA's technical architecture makes it superior to other technologies in both upstream and downstream bidirectional communication. It claims to have better Doppler effects, scheduling algorithms, and immunity to interference. It operates in the 2.4 GHz (for WiFi and Bluetooth) bands available worldwide. This means that it does not require changes and adjustments to the technical architecture of different regions like SigFox and LoRa.
According to its internal research, RPMA has higher communication distance indicators: RPMA is 177, SigFox and LoRa are 149 and 157, respectively. This means that RPMA has greater coverage.
Symphony LinkLink Labs is a member of the LoRa Alliance, so it uses the LoRa chip. However, Link Labs did not use LoRaWAN, but built a proprietary MAC layer (software) called Symphony Link on top of Semtech's chip.
Founded in 2013, Link Labs is a former member of the Johns Hopkins University Applied Physics Laboratory and is headquartered in Annapolis, Maryland.
Compared to LoRaWAN, Symphony Link adds some important connectivity features, including: reliable message delivery, firmware over-the-air upgrade, duty cycle limitation, relaying, and dynamic expansion.
WeightlessThe Weightless SIG (Special Interest Group) was established in 2008 with the mission of standardizing LPWAN. There are five sponsoring members, including Accenture, ARM, M2COMM, Sony Europe and Telenasa.
Weightless is the only truly open standard in the unlicensed spectrum below 1 GHz. There are three versions of Weightless for different application scenarios:
Weightless-W: Not used yet (authorizes unused local spectrum in the TV band)
Weightless-N: Unlicensed Spectrum Narrowband Protocol Born by NWave Technology
Weightless-P: A two-way protocol born of M2COMM's Platanus technology
Although Weightless-W has lower power consumption, Weightless-N and Weightless-P are still more popular.
Weightless-N/NWaveNwave is very similar in functionality to SigFox, but it claims to have a better MAC layer implementation. It claims to use advanced demodulation techniques to support the coexistence of its own network with other radio technologies, and this coexistence does not cause additional communication interference. Like SigFox, it is best at sensor-based network communication, temperature acquisition, water level monitoring, smart measurements, and other similar applications.
Weightless-PThe standard uses FDMA + TDMA modulation in a 12.5 kHz narrowband (greater than SigFox but less than LoRa). It also has an adaptive data rate similar to Symphony Link (200bps to 100kbps). It has high sensitivity and a signal strength of -134 dBm at a transmission rate of 625 bps, while supporting PSK and GMSK modulation.
Weightless-P is applicable to private network application scenarios where both uplink data and downlink data have important requirements and services are complex. A development kit for Weightless-P is available.
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