More and more, in projects such as smart city or smart parking, users are faced with the need to install low-power devices that transmit small amounts of data over long distances. Rather than 3G/4G that is not optimized for this purpose, the low-power wide area network (LPWAN) technology stands as an ideal option. Currently there are different LPWAN technologies in the market, and the user should select a technology based on their demands and needs.

Izvor: a&s International

E-mail: redakcija@asadria.com

LPWAN has gained popularity in recent years, and that trend is expected to continue. In a research note, ABI Research estimated that 4 billion IoT devices are expected to rely on LPWANs by 2025, with the potential to generate a total value of more than US$2 billion.

For low-power devices that transmit small data over long distances, LPWAN provides an option that works more effectively than other wireless technologies. “Many potential ’connected things’ are located in remote or hard-to-reach areas at long distances from the next cellular base station. When there is coverage, it is often poor and requires the device transmitter to operate at high power, draining the battery,” said Steve Dunn, CEO of LEAPIN Digital Keys. “Additionally, cellular networks are not optimized for applications that only transmit small amounts of infrequent data. Further, the existing cellular standards don’t support power saving capabilities, which makes these standards unsuitable for inexpensive devices that require battery lives of several years.”

“Wireless transmissions from IoT end nodes often must communicate across long distances or need to penetrate barriers such as concrete or soil. LPWAN technologies are a good option for these conditions, enabling data that might otherwise be inaccessible or too costly to access to be connected to the cloud,” said Tom Pannell, Senior Marketing Director for IoT Products at Silicon Labs. “Ultimately, LPWAN connections help provide more insights into what is happening in the physical world — that is, via sensor nodes in our homes, offices, factories and urban infrastructure – thus contributing to real-time cloud-based analytics.”

TECHNOLOGIES AND APPLICATIONS

Currently many LPWAN technologies exist; these include NB-IoT, LoRa, Sigfox, HaLow, RPPM and Weightless. Each has unique features and characteristics that users should know before deciding which technology is most suitable for them.

NB-IoT

NB-IoT (NarrowBand IoT) is a LPWAN technology standardized by the 3rd Generation Partnership Project (3GPP), the same group that specified the LTE technology. As such NB-IoT operates in the same spectrum as LTE. Ecosystem partners include Huawei Technologies, Ericsson, Qualcomm Technologies, Deutsche Telekom, Vodafone Group, Intel and Nokia.

“Since NB-IoT operates in licensed spectrum, it is secure and reliable providing guaranteed quality of service,” Dunn said. “NB-IoT will eventually work virtually anywhere in mobile network operators’ existing infrastructure. It connects devices more simply and efficiently on already established mobile networks, and handles small amounts of fairly infrequent two-way data, securely and reliably.”

NB-IoT has various applications from smart parking to smart hotels. “We see NB-IoT as being most applicable for use in hotels. This solution is going to create value for hotels and guests alike as being able to add digital keys to hotel guest loyalty apps. This will streamline hotel operations and help them to capture data to improve the overall guest experience,” Dunn said. “We also believe there are many new applications for smart locks in areas that don’t require on-site power or Wi-Fi such as parcel delivery lockers, storage spaces, cabinet locks and even vehicles.”

LoRaWAN and Sigfox

LoRaWAN is another popular LPWAN technology. It is specified by the LoRa Alliance whose members include prestigious IT firms including Cisco, IBM and Renesas. According to the alliance, LoRaWAN transmits data at rates from 0.3 kbps to 50 kbps.

Sigfox meanwhile is a French company that created the Sigfox LPWAN technology, whose ecosystem partners include NXP, ON Semiconductor, Wisol and InnoComm. According to the company, Sigfox operates in the 200 kHz of the publicly available band to exchange radio messages over the air, with each message being 100 Hz wide and transferred at 100 or 600 bits per second, depending on the region.

According to Pannell, LoRa and Sigfox are best suited for city surveillance applications. “This involves disparate, spread-out end nodes, which are often located in hard-to-reach environments. A good example is a vibration sensor embedded in a bridge, providing data on the bridge’s physical condition and potential for stress-induced failure,” he said.

Wi-Fi HaLow

Wi-Fi HaLow is developed by the Wi-Fi Alliance. According to Randy Ryder, Marketing and Business Development Manager at Wi-Fi Alliance, the technology operates in the 900 MHz portion of the radio spectrum (as opposed to 2.4 GHz and 5 GHz for traditional Wi-Fi), transmits data at a low of 150 kilobits per second to 18 megabits per second, and has transmission range of up to 1 kilometer.

The setup of a HaLow network is basically the same as setting up Wi-Fi. A sensor integrated with the HaLow technology, for example in the form of a HaLow module, is connected to a Wi-Fi access point. Data is transmitted to the access point and is then propagated to the internet. “Some of the benefits of Wi-Fi HaLow, and why there is the expectation that it will grow and gain a lot of traction within IoT, is the fact that it leverages a tremendous installed base of Wi-Fi devices,” Ryder said. “Another key benefit is that Wi-Fi HaLow ensures interoperability with this existing installed base as well as future deployments.”

According to Ryder, Wi-Fi HaLow is suitable for both indoor and outdoor applications, especially in challenging RF environments where walls, concrete and other obstructions are present. “Because of Wi-Fi HaLow’s ability to operate in challenging environments, a great use case for the technology is an underground parking garage. The sensors in each parking spot can be connected via Wi-Fi HaLow to the main network, and people with smartphones are then able to see which parking places are open and which are occupied,” Ryder said.

RPMA

RPMA (Random Phase Multiple Access) is another LPWAN technology developed by Ingenu, offering data in the 2.4 GHz spectrum. “Ingenu’s RPMA technology is a low-power, wide-area network technology which is ideal for low data rate applications. It is currently deployed in the following markets: smart grid, asset tracking, agriculture, smart city, transportation/logistics and other industrial applications,” said Ted Myers, CTO of Ingenu. “Ingenu is constantly refining its RPMA technology, with the caveat that it will always be backwards compatible. This means that the network that is installed today will remain operational for years, even decades.”

Weightless

Weightless meanwhile is another LPWAN technology developed by the Weightless SIG. According to the group, the technology offers data in the 169/433/470/780/868/915/923 MHz channels at rates from 200 bps to 100 kbps, with a range of 2 kilometers in an urban development.

USERS DECIDE

HaLow, RPMA and Weightless add to Sigfox, LoRaWAN and NB-IoT to form the primary LPWAN technologies at the moment. According to most of the organizations or alliances that we spoke to, there is room for these technologies to coexist in the LPWAN arena, which is unlikely to see a consolidation of technologies or a “winner-takes-all” scenario. Rather, according to them, it’s up to the user to determine what is the right technology for them, which should be based on various factors — for example how long is the range, how much data is transmitted by the devices at what intervals, or is the battery life measured in months or years.

“The answer depends on the developer’s application requirements and the environments in which the LPWAN solution will be deployed. Three key factors to consider include power consumption, payload and performance — that is, wireless transmission over distance and through barriers like concrete walls,” said Pannell.

“The primary question that users should ask themselves is what are the needs of my use case — what kind of battery life do I need, what kind of range do I need, and what type of data throughput do I need? Then, find the specific technology that fits those needs,” Ryder said.

“Users should choose the technology that best suits IoT applications. The technology should be cost-effective, able to scale, and have the longevity to support many of the IoT devices that can operate for over a decade,” Myers said. “Additionally, a network that has been designed to serve machines only typically uses a fraction of the data that other networks consume. Most IoT applications (nearly 85 percent) use less than 3 MB of data per month, so this should be considered before investing in a network that may be overkill for a typical application.”

ENDURING POPULARITY

LPWAN is a broad term that addresses various technologies enabling long-distance transmission of small data between low-power devices. At this time it remains unlikely that one dominant technology is going to emerge any time soon. What we can foresee, however, is that LPWAN is going to remain popular given the rise of IoT and its applications in smart city and other projects.