LPWA

LPWA stands for Low-Power Wide-Area. It does not refer to any one specific technology, but rather serves as a generic term for any network designed to communicate wirelessly with lower power than other networks such as cellular, satellite, or WiFi.

Moreover, LPWANs communicate over greater distances than other low-power networks that use Bluetooth or NFC, for example.
LPWA is also referred to as LPWAN, where the N stands for network. LPWA is similar to the terms LAN or WAN in that it does not have an official, specific definition.

Typically, communicating over long distances with low power allows only small amounts of data to be transmitted at a time. Whereas modern cellular networks are pushing into gigabit per second territory with LTE Advanced and the forthcoming 5G networks, LPWA networks transmit much less—often just a few kilobits per channel. On the other hand, many LPWA technologies can communicate over greater distances, sometimes up to 500 miles or more.

What is LPWA used for?

The very limited bandwidth of LPWA networks are not suitable for most consumer and commercial applications such as voice, video, audio, or even text messaging. As such, LPWA networks are used almost exclusively by devices on the Internet of Things (IoT), and M2M (machine-to-machine) communications.

While home-based or business-based devices such as refrigerators, lightbulbs, or Nest thermometers can all easily piggyback on a home or office WiFi connection, some devices cannot rely on such connectivity.

Consider an irrigation ditch that stretches over miles in America’s farm country. Along this chain of streams and ditches are hundreds or even thousands of pumps and gates. Much of the irrigation channel runs through private land, between crop fields, and across several miles. As such, following the path even once per day to ensure that the pumps are running properly is impractical, not to mention of limited value. If a pump near the far end fails, it might be hours until you get to it. If one fails behind you, you might not know until the next day.

In cases like these, there is no local network to access. Standard cellular networks out on the plains are spotty, or non-existent in many areas. A satellite connection might work, but would be very pricy, and such a connection takes a lot of power. In this case, an LPWA network is exactly what is necessary.

With a range of up to dozens of miles, the network of pumps can all connect easily and inexpensively. Although the amount of data transmitted is limited, it takes surprisingly little data to do something like provide the status of a water pump. A single number can convey an overall status: one number for normal operation, a series of others for various error conditions, and another number could signify the number of gallons pumped per day. This system would allow farmers to monitor every pump on the line from a central console. An error condition for overheating, plus a drop in the number of gallons pumped, might signal a failing pump. Early warnings like this allow for technician to be notified in advance. All from a tiny, periodic, data transmission.

From devices located in mountaintop weather stations and lights in a multiple-acre greenhouse complex, to traffic lights, train crossing signals, and more can all be monitored, and in some cases even managed, with the limited data and low-power requirements of LPWA.

LPWA technologies

Recent IoT security issues have made headlines. For example, the Mirai attack worked to gain access to end devices. Such attacks may be less useful on many IoT devices using LPWA due to lower bandwidth, and the fact that the connected devices may not be “smart” enough to be useful to a hacker. However, man-in-the-middle attacks are possible on many LPWA networks. The potential for abuse is less spectacular, but just as important. Spying on competitors by receiving their device reports is one possibility, and unlike traditional hacking, because these signals are broadcast out into the air, there wouldn’t be any way to know the communications have been compromised.

One problem is that the end devices themselves are often not capable of providing their own encryption. A shared hash might be a good solution, except that many networks require packet sizes too small to implement a hash that is long enough for ongoing security. For example, the Sigfox LPWA technology only offers a 16-bit digital signature, which is far below the 128-bit industry standard. LoRaWAN, however, offers AES 128-bit encryption and authentication.

Cellular-based technologies, like LTE-M, NB-IOT, as well as EC-GSM-IoT piggyback on the authentication of the existing network.

Current LPWA uses

While there are many possibilities for LPWA networks, some concepts are more established than others.

Parking management

There are a lot of applications in the area of parking management. A sensor in or near a parking spot can report whether the spot is occupied or not. The data can then be used to feed numerous applications including signs that show how many open parking spots are available on a parking garage level. Or in apps that show where there are open meters as well as interfaces that tell a city where a car has been parked at a meter for too long. In this application, the low power matters more than the long distance for LPWA networks. No one wants to take on the burden of changing the batteries in hundreds or even thousands of parking spot monitors.

Water meters and pipelines

A simple pressure meter communicating its current reading can help pinpoint a leak even before it is reported. For pipelines that stretch over miles the ability to communicate over long distances without an existing network is critical, and battery life needs to be measured in years. In a city, the same signal that provides long-distance communication in a rural environment can provide underground communication instead, allowing monitoring of pipelines buried beneath the city.

Smart pallets

Tracking shipments typically require that cargo is scanned at every point in which it changes hands. Between these changes, it is simply assumed that the cargo is still in the same building, or when on the move, in the same truck or train. With a smart pallet, a ping can continuously update not only the location, but also whether the container has been opened, dropped, or otherwise mishandled. LPWA is needed both for long distance communication while the shipment is on the move between cities, and for the long battery life, because no one wants to find and change the batteries on frequently moved pallets.

Street lighting and highway lighting

There are tens of thousands of lights out there shining on neighborhood sidewalks, busy intersections, and lonely stretches of highway. These days, monitoring often consists of nothing more than someone noticing and making a phone call. With LPWA, these lights can let a central command center know if the bulb is working, or if the light is currently on, potentially allowing for better energy usage and increased safety.

Other uses include smart meters (home and commercial), as well as smart agriculture, and factory and warehouse sensors.

LPWA fragmentation

The market for LPWA networks offers several choices. Some see this as fragmentation, while others see it as a market where the offerings can be chosen based on what is best for each particular project. For now, while LPWA demand is growing, there isn’t a one-size-fits-all solution available.