What is LPWAN?

LPWAN (Low-Power Wide-Area Network) is a type of wireless network designed to allow long-range communications at low data rates among host devices (Gateways) and sensors. LPWAN technology supports packet sizes from 10 to 1,000 bytes at uplink speeds up to 200 Kbps. The operating range of LPWAN technology varies from a few kilometers in urban areas to over 10 km in rural settings.

LPWAN does not refer to a single technology, but rather is a group of various low-power wide area network technologies like SigFox, LoRa, NB-IoT, LTE-Cat M etc. LPWAN’s can use both licensed and unlicensed frequencies and includes proprietary or open standard options.

An LPWAN network must possess the following properties:

• Long Range: The operating range of LPWAN technology varies from a few kilometers in urban areas to over 10 km in rural settings. It can also enable effective data communication in previously infeasible indoor and underground locations.
• Low Power: Optimized for power consumption, LPWAN transceivers can run on small and inexpensive batteries for up to 20 years
• Low Cost: LPWAN's simplified, lightweight protocols reduce complexity in hardware design and lower device costs. Its long range combined with a star topology [RK1]reduce expensive infrastructure requirements and the use of license-free or licensed bands reduce network costs.
• Fewer Access Points: Requires fewer access points (base stations, gateways) to cover wide areas like cities or even a country.
• Good Propagation & Penetration: Usually operates in the Sub-GHz ISM band (Unlicensed Spectrum) which has good propagation properties and can provide good coverage in dense areas with penetration through buildings and walls. Certain LPWAN technologies such as NB-IoT operates in the licensed portion of the spectrum.

There are a number of wireless technologies that can be used for a wide range of low power, wireless applications today. Most IoT and M2M solutions require a long-range communication link with low bandwidth and data rates. Traditional technologies are not ideal for such applications which has given rise to the requirement of LPWAN Technologies.

Some Common LPWAN Technologies are:

Sigfox: Running over a public network in the 868 MHz or 902 MHz bands, this ultra-narrowband technology only allows a single operator per country. The downlink packets are smaller and limited to four messages of 8 bytes per day. Sending data back to endpoints can also be prone to interference. It can deliver messages over distances of 30-50 km in rural areas, 3-10 km in urban settings and up to 1,000 km in line-of-site applications. The packet size is limited to 150 messages of 12 bytes per day.

Click here to learn more about Sigfox.

LoRa (Long Range): The unlicensed LoRa technology is specified and backed by the LoRa Alliance. It uses sub-GHz frequencies (different frequencies in different countries) which allow it make it less prone to interference and allow it to propagate though walls and buildings.

LoRa allows users to define the data packet size up to 255 bytes and uses a derivative of chirp spread spectrum (CSS) modulation. It uses a media access control (MAC) layer protocol called LoRaWAN that manages communication between LPWAN devices and gateways. The stated range of LoRa is more than 10 km in rural areas (Clear Line of Sight) and 2 km in urban areas.

Click here to learn more about LoRa Technology.

NB-IoT (Narrow Band): NB-IoT is a cellular IoT based LPWANradio technology standard developed by 3GPP (3rd Generation Partnership Project) to enable a wide range of cellular devices and services. NB-IoT is a low cost cellular technology that can be used with battery operated devices. It has a low latency of 10s and has a data rate up to 26 Kbit/s. NB-IoT is a subset of the LTE standard but limits the bandwidth to a single narrow-band of 200 KHz. It follows half-duplex technology with a transmitting power of 23 dBm and has a receiver bandwidth of 180 KHz.

Click here to learn more about NB-IoT.

LTE –M (Long Term Evolution for Machines): LTE-M is a LPWAN technology developed for IoT applications. The protocol is suitable for low bandwidth cellular communications that connects to the internet low complexity devices that transmits small amounts of data over long periods of time with low power consumption. LTE-M latency is in the region of 50-100ms and the two variants M1 and M2 have data rates up to 2984 bits and 4008 bits respectively. 

Click here to learn more about LTE-M.

There are many other LPWAN Technologies such as GreenOFDM from Green Waves Technologies, DASH7 from Haystack Technologies, Symphony Link from Link Labs, ThinkPark Wireless from Actility, WAVIoT etc.

LPWAN Technology is used in a wide range of applications including smart metering, smart lighting, asset monitoring and tracking, smart cities, precision agriculture, livestock monitoring, energy management, manufacturing and industrial IoT deployments. Choosing a specific LPWAN technology depends on the application, range, data rate, battery life, latency and a number of other parameters. LPWAN’s are best suited for applications that require infrequent uplink message delivery of smaller messages. Most LPWAN technologies also have downlink capabilities.

Different LPWAN technologies also offer varying levels of security. The level of security includes device or subscriber authentication, network authentication, identity protection, advanced standard encryption (AES), message confidentiality and key provisioning. 

The potential of LPWAN is huge. As per market research reports more than 20 billion of IoT devices will available by 2020 and a large portion will be connected with LPWAN. There are several LPWAN technologies present on the market now. They differ from one another by frequency, bandwidth, RF modulation approach and spectrum utilization algorithms. And as a result, they have their key points to consider when choosing the right technology for a specific Internet of Things Application.