Low-power wide area network or LPWAN technology interconnects low-bandwidth devices. They are powered by battery. Moreover there are low bit rates over long ranges.
LPWANs have been designed for internet of things (IoT) and machine-to-machine (M2M) networks. It offers high-efficiency at a comparatively low cost. The LPWAN technology has the capability of supporting much more number of connected devices than the traditional mobile networks. The range covered by LPWAN may vary from 2km to 1,000km as is mostly dependant on the technology.
The massive growth of the internet of things has led multifarious industries to incorporate connected technologies that will make the society more interactive and connected. As per the Global Standards Initiative on the IoT, the IoT devices must be energy efficient, and have faster and wider range internet connectivity, advanced sensors and processors, secure platform. The IoT must also be cost-effective, reliable and high-quality. Four different low-power wide area network technologies have made its way into the IoT market. These technologies make the internet of things attractive for implementation in commercial applications.
In case of the smart meters, the requirement is long battery life (nearly 10 years without charging) as well as long range connectivity. These criteria cannot be met by short range communication technologies like Zigbee and Bluetooth. Presently, the 3G and 4G cellular networks meet the requirements of IoTs but, the consumption of power is very high. The LPWAN technologies do not consume so much power and also offer cost-effective options for a wider range.
LoRa technology was developed by the French startup Cycleo in 2009. Moreover, it was acquired by Semtech in 2012. After the acquisition, The LoRa Alliance became popular independently as an open. Non-profit association even though Semtech continues to be the only provider of the main chip used for LoRa. With a bandwidth of 250kHz and 125kHz, LoRa allows bidirectional communication. LoRa uses the ISM unlicensed spectrum where the maximum data rate is 50Kbps. It has a maximum payload of 243 bytes. LoRa is basically a physical-layer technology that implements the CSS (chirp spread-spectrum) modulation technology for modulating the signals in the sub-GHz ISM band. CSS can be traced back to 1940s when it was mostly used for various military applications. Long-distance communications ability is the USP of CSS. As per the statistics relayed by Semtech led LoRa Alliance, nearly 83 network operators are using LoRa technology in 49 countries.
Sigfox was also first developed in France in 2010 and implements an ultra-narrowband (100Hz) technology. This has been developed by Sigfox. It has a maximum data rate of 100bps. The technology also functions in the unlicensed ISM spectrum and has really small payload, a maximum of 12 bytes. This is one of the major factors in Sigfox that allows greater coverage geographically. The reach of Sigfox LPWAN technology can cover up to 10k in the urban areas and nearly 40km in rural areas. Previously Sigfox had only supported uplink communications, but has now developed into bidirectional communications. However, there is a limit to the amount of daily uplink messages (140). The objective of Sigfox is to reduce the costs and battery consumption as much as possible.
NB-IoT and LTE-M have brought in many changes in the LPWAN market that have increased the use cases in IoT applications. They are 3rd Generation Partnership Project (3GPP) and addresses the LPWAN requirements for various internet of things applications.
Narrowband IoT (NB-IoT)
Narrowband IoT is based on licensed cellular networks. It can exist alongside GSM and LTE. Based on LTE protocol, the technology offers a bandwidth of 200kHz and a maximum data rate of 200kbps. NB-IoT provides bidirectional communications with unlimited messages where the maximum payload is 1600 bytes. The LTE cellular network in the Narrowband IoT technology gives a wider reach and deeper penetration into the multi-storeyed complexes, remote areas as well as underground. This technology can be widely applied in smart metering, manufacturing automation and retail point of sale. Private networks will find it a little costly. Narrowband IoT has many improvement areas but is growing rapidly by focusing on low cost and low power consumption.
Long-Term Evolution (LTE) Category M1 (LTE-M)
Long-Term Evolution (LTE) Category M1 like NB-IoT focuses on low power and long distance measurements. Compared to NB-IoT, LTE-M offers a wider bandwidth of up to 1.4 MHz and a higher data rate. LTE-M supports both mobility and voice communications. It can be easily applied in cases where higher data rate is required. Thus, LTE-M technology can be incorporated into home security, patient monitoring and tracking.
The rapid growth of the IoT market has led to the emergence of LPWAN network technology that offers long-range communications with low power consumption. Each of the LPWAN technologies developed till now has its own pros and cons and there is much more to see in this area.