Wi-Fi HaLow: Wireless for the internet of things

Wi-Fi HaLow, the marketing term the Wi-Fi Alliance has chosen for the IEEE 802.11ah standard, is a long- range, low-power, low-speed version of traditional Wi-Fi. It shows promise with deployment of Internet of Things (IoT) devices such as sensors, wearables, machine-to-machine (M2M) applications, smart buildings, and smart cities.

With the ability to connect low-bandwidth devices to IP networks including the internet, it supports enough bandwidth to handle HD-quality video and can even be used for rural communications and offloading cell phone tower traffic.

The HaLow standard was approved in September 2016 and published in May 2017. Unlike the similar low-power standard 802.11af, which operates in the television white space spectrum in VHF and UHF bands, HaLow operates in unlicensed bands, so it’s easier to deploy.

HaLow also has advantages over similar technologies in the unlicensed spectrum because some of them are built on proprietary standards. Other technologies are also more complicated, requiring proprietary hardware to get IP connectivity to the client devices. HaLow is intended to make deploying IoT devices easier.

Despite these advantages, uptake has been slow. On the Wi-Fi Alliance’s product finder, just three companies are listed as having Certified Wi-Fi HaLow products: Methods2Business with an AP and client, plus Newracom and Morse Micro, which make systems-on-a-chip (SoCs) that are utilized in end-user devices and clients.

Why use HaLow?

Most Wi-Fi technologies, such as Wi-Fi 5 and Wi-Fi 6, operate at frequencies in the 2.4 and 5 GHz bands. Wi-Fi HaLow utilizes license-exempt frequencies below 1 GHz, such as 902 – 928 MHz in the United States.

Lower frequencies mean longer signal ranges and better penetration of the signal through walls and other materials. Thus, Wi-Fi HaLow signals can travel much farther; even reaching distances over 1 km (0.62 miles).

Since devices utilizing HaLow aren’t high-performing bandwidth hogs, they can use lower power radios. This means the wireless connectivity consumes very little power, thus giving the devices long battery life—in some cases more than five years.

HaLow compliments traditional Wi-Fi well by enablinh network architects to move lower bandwidth clients off the main Wi-Fi network. Idle clients don’t hog airtime, but they do have some impact on the network performance, especially if you want to deploy hundreds or thousands of IoT wireless devices. With Wi-Fi Halo, you can give them their own band to operate in and reserve the higher bands for devices that need more throughput.

Even though HaLow is designed for lower bandwidth applications, it can still provide enough throughput for HD-quality video cameras. This depends on the capabilities of the access point and the client-device specs, and distances, but it is possible.

What infrastructure does Wi-Fi HaLow require?

Unlike similar IoT technologies, Wi-Fi HaLow doesn’t require proprietary controllers, hubs, or gateways. All you have to do is plug a HaLow access point into a traditional LAN and HaLow clients can connect to to IP-based networks including the internet. Or they could choose a gateway device with 4G LTE connectivity to the WAN.

Right now, traditional Wi-Fi access points support 2.4GH and 5GHz bands but don’t support the HaLow band. However, with the longer ranges, one AP placed in the proper location could cover an entire multi-floor office building or warehouse. This would depend on many factors, including the data rates you want to provide to the clients, transmit powers, antennas, and interference. Wi-Fi HaLow can also be deployed in a wireless-mesh mode to take the signal farther without a wired connection.

What are Wi-Fi HaLow channel schemes and data rates?

Wi-Fi HaLow in the United States has 26 1MHz channels in the 902MHz to 928MHz range, each able to provide 100 Kbps throughput. Like traditional Wi-Fi, HaLow devices have channel-width options to increase bandwidth. There are five channel-widths from 1MHz to 16 MHz, however not all devices support all the widths.

Remember, the narrower a channel, the farther the transmissions will travel, but at slower data rates. For long ranges like 1km with some RF attenuation you’d likely see a 150kbps data rate utilizing just one 1MHz channel. The best-case situation with shorter ranges or line of sight is a theoretical 86.7Mbps with 16MHz channels and short guard intervals.

Newracom claims it achieved 2Mbps of UDP throughput at 3km with line-of-sight. The trial was carried out at sea with no radio interference. Under ideal conditions, then, a few Mbps speed could be expected at 1.5km.

What about interference?

The 900 MHz band does have other unlicensed users and devices in addition to Wi-Fi HaLow. Back in the day, it was pretty crowded with cordless phones. Ham radio operators also have a right to utilize the band, but on a secondary basis. This means they have to accept interference from other sources as they are not the primary users of the band.

Compared to the number of Wi-Fi 5 and Wi-Fi 6devices using the 2.4GHz and  GHz bands, interference shouldn’t be a big issue when using Wi-Fi HaLow. Also, because Wi-Fi HaLow devices tend to deliver smaller amounts of data and less frequently compared to traditional Wi-Fi devices, competition for airtime is less of a concern.

How secure is HaLow?

Wi-Fi HaLow supports the same Wi-Fi Protected Access (WPA3) security and Wi-Fi Enhanced Open functionality as traditional Wi-Fi devices, so HaLow is just as secure as traditional Wi-Fi. Some devices may also support the enterprise mode of WPA3 with 802.1X authentication. Although the legacy WPA2 security isn’t required for Wi-Fi Certified products, some HaLow devices may support it.

Is HaLow ready for enterprise deployments?

There are few Wi-Fi Halow devices on the market yet, but they are ready for enterprise deployments now, according to Newracom and others. In addition to the Wi-Fi Certified products, there are products supporting Wi-Fi HaLow that have not been certified yet. Among them:

• Alfa provides an outdoor AP/CPE with PoE, a USB Type-C HaLow AP/CPE, and modules.
• DeviceWorx produces Industrial IoT gateways, sensors. and beacons.
• Elastel has an IoT gateway along with other IoT offerings.
• Palma Ceia SemiDesign has an 802.11ah access point, station/client device, and transceivers.
• Silex Technology has an 802.11ah access point, wireless bridge, and modules.

Some companies provide just the Wi-Fi modules, such as Airetos/VoxMicro, Azurewave, LiteOn, and Reyax.

Like traditional Wi-Fi networks, it’s recommended to do RF site surveying before and after deploying Wi-Fi HaLow. This is especially true since it’s likely an unfamiliar technology for most network engineers. You want to do live testing and analyzing, especially if you plan to use Halow over long distances or have higher bandwidth clients to serve.

(Eric Geier is a freelance tech writer and founder of NoWiresSecurity, providing a cloud-based Wi-Fi security service; Wi-Fi Surveyors, providing RF site surveying; and On Spot Techs providing general IT services).

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