The Pros and Cons of Different LPWAN Networks for Your IoT Application

Right now, IoT is like a gladiator battle in the coliseum of market forces and public opinion. There are constant rankings of what protocol or stack to use, which IoT products are useful (or not), and who’s going to win each element of the burgeoning IoT ecosystem. The best part is that each of these little battles is also a decision that you must face or plan for in your next IoT design. Awesome, right?

Lucky for you, I’ve already considered the odds of one of the current big gladiator matchups in IoT; should you use a low power, wide area network (LPWAN) for your IoT system?

Another IoT protocol? What do I need to know?

LPWANs are a big change from networks that piggyback on the internet or mobile communications. We’ve talked about them recently, but the bare bones of the application to IoT systems are:

Low Power

It’s so important that it’s even part of the name. Unlike existing cellular networks, LPWAN is intended to minimize the power cost to an IoT system. Devices generally don’t produce more than 10-25 mW for compliance with ISM frequency bands. This allows remote sensors or devices to operate for extended periods of time (ideally, years) without needing to change batteries.

Wide Area Coverage

LPWANs have coverage ranging from a few kilometers in urban areas up to 15-30 in rural areas without lots of interference. They have much wider coverage than short to medium range systems like Bluetooth or Wi-Fi.

Low Bandwidth

Because most IoT devices are sending small amounts of data, low bandwidth reduces system cost. LPWANs are intended for applications with small messages only a few times per hour, rather than data-heavy applications like streaming.

Low Cost

Most LPWANs are using a subscription model, allowing hardware (the radio chipset) to be cheap, while an annual subscription fee is charged for each device connected to the network. Many use the unlicensed spectrum in the ISM bands (such as 868 MHz in Europe and 915 MHz in the US) to reduce cost.

Who uses LPWAN?

Consumer applications on LPWANs are still nascent, so they are not widely used. However, SigFox is gaining momentum in Europe, and IoT Central reports a 6% increase in adoption over the last year. Current applications are mostly industrial and are transitioning into “smart cities,” where utilities and services are finding more use cases.

What are my network choices?

Like everything in the IoT space, there are a lot of contenders and many more opinions about which ones are good. If you’re interested in an even more detailed comparison, IoT For All has a white paper at the end of this article that might be of interest.

LoRa and SigFox are the biggest LPWAN competitors, but there are some underdogs with a lot of potential.

The LPWAN heavyweights are LoRa and SigFox. However, a few of the underdogs, like Ingenue and Weightless are definitely worth a look. To start, let’s explore what the heavyweights have to offer.

LoRa

LoRa has gained momentum in Europe, where there are already deployed coverage areas. It requires the use of a radio chipset from Semtech, so it’s not an open standard.

Pros:

• Great industry support and partners, including Cisco, IBM Microchip Technology, KPN, IMST, and more.

• Comparatively decent bandwidth (for LPWAN, you’re not going to be streaming YouTube clips here)

• Security: AES CCM (128 bit) encryption and authentication

Cons:

• Not an open standard

• You can only use vendors approved by Semtech

• Private networks are difficult/impossible on LoRa

• Difficult validation/acknowledgment protocols and high error rates

• Limited downlink capability

SigFox

Our other major big contender is also already deployed. SigFox also has strong industry support from partners like Texas Instruments, Silicon Labs, and Axom.

Pros:

• SigFox has deployed with a lot of traction in Europe and San Francisco

• There is no receiver circuitry, so less power is required.

• Longer range, achieved at the cost of slower modulation, making SigFox ideal for simple metering applications

Cons:

• Not an open standard

• US architecture is different from what has been deployed in Europe due to the transmission length mandated by the FCC, so testing may not be as robust.

• Minimal security (16 bit encryption)

• No downlink communication

• Potential for higher RF interference

Ingenu

Ingenu has been slower to market than SigFox or LoRa because it spent a lot of time and effort developing the full LPWAN technology stack. Ingenu was a founding member of the iEEE 802.15.4k task group, working on low-energy infrastructure data monitoring, so they are strong on the fundamentals.

Pros:

• Architecture development with superior uplink and downlink capacity, compared to other LPWANs.

• Higher link budget than LoRa or SigFox, providing greater, and more robust, area coverage

• International compatibility with operation at 2.4 GHz.

Cons:

• Increased interference from WiFi, Bluetooth, and buildings with 2.4 GHz operation

• Shorter battery life due to higher device processing power consumption

Weightless

Weightless is another sub-1 GHz LPWAN, operating in the unlicensed spectrum. I’m particularly fond of it because it’s the only open-standard in that space, and I love the potential that offers for new applications. There are three standards, N, W, and P. You can balance cost against speed and extensive feature sets to choose which is best for your system.

Pros:

• Options for low-speed sensor networks (N), or adaptive rate private networks (P)

• Uplink and downlink capability (P, W)

• Good range in urban environments (2-5+ km)

• Co-exists with other RF technologies with minimal interference using advanced demodulation

Cons:

• TV white space spectrum is required for Weightless W

• Battery life ranges from 2-10 years, depending on the standard​

The Underdogs

Several other options exist. but have yet to gain much traction. These include LTE-M, IEEE P802.11AH (a low power wifi option), and Dash7. In order to deploy your IoT device, you need an LPWAN to be readily available, so these aren’t great choices--yet. They are definitely contenders to keep an eye on.

Should I use an LPWAN?

Like other IoT communication protocols, there’s not an easy answer as to what’s right for you. However, there is an easy answer if LPWAN is not right for you. Start by finding out your coverage options anywhere you want to deploy your systems.  If there’s no network, then designing for that LPWAN is like betting on a gladiator who’s not even in the fight.

There’s a big lineup of LPWAN contenders, but make sure you pick one that makes sense for where you want to deploy.

While we’re waiting for the thumbs up on which protocols are going to be most widely accessible and supported, you’re probably better off with something more tried and true. Don’t lose track of LPWAN, though. If you want your IoT devices to have long-term compatibility, you need to keep them on your radar.

If you’ve done your research and you’re ready to start designing your IoT products, make sure you manage your components and requirements over the long term. PCB software like Altium Vault^® make it easy, and also help you manage version control when you’re ready to integrate hardware for new network options. You can contact an Altium representative today to get started!

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