Wi-Fi HaLow (802.11ah): range, speed and uses

Wi-Fi HaLow (pronounced “halo”) is Wi-Fi that runs in the license-exempt bands below 1 GHz. It was published by the IEEE in 2017 as the 802.11ah amendment, and the Wi-Fi Alliance started certifying products under the HaLow name in 2021. It exists for jobs that ordinary Wi-Fi does badly: a camera at the far gate, a sensor in a barn, a meter behind three concrete walls. This guide explains how it reaches that far, what you give up for it, and where it beats the alternatives. It sits in the connectivity hub beside the guides on LoRaWAN and 2.4 vs 5 GHz Wi-Fi.

What makes HaLow different from normal Wi-Fi

Everyday Wi-Fi uses the 2.4, 5 and 6 GHz bands. HaLow moves down to roughly 750 to 930 MHz, depending on the country. Two physical facts follow from that.

Lower frequencies travel further and pass through obstacles better. A sub-1 GHz signal loses less strength over distance and through walls, foliage and floors than a 2.4 GHz one. This is the same reason LoRa, Z-Wave and older cordless phones use these bands.

Narrow channels hear weaker signals. HaLow channels are 1, 2, 4, 8 or 16 MHz wide, against 20 MHz and up for normal Wi-Fi. A narrow channel collects less noise, so the receiver can pick out a fainter signal. The cost is speed: a 1 MHz channel carries far less data than a 20 MHz one.

Above the radio, HaLow is still Wi-Fi. Devices join a network with a name and a password, get an IP address, and talk TCP, UDP, MQTT or HTTP like any other networked device. That is the main thing that separates it from LoRaWAN, Zigbee and Thread.

Bands and channel widths

HaLow uses whatever license-exempt sub-1 GHz spectrum each region allows, so the details change at the border:

• United States: 902 to 928 MHz. This is the widest allocation, with room for 1, 2, 4, 8 and 16 MHz channels, so US products get the best speeds.
• Europe: a narrow slice around 863 to 868 MHz, shared with LoRa and other devices and subject to limits on how much of the time a device may transmit. Only the narrow channel widths fit, which caps speed and makes HaLow less attractive there for now.
• Elsewhere: Japan, Australia, parts of Asia and others each have their own range and rules.

The practical rule is simple. Buy hardware sold for your country, check that the access point and every device use the same regional setting, and do not import a US kit for use elsewhere: it may be transmitting on frequencies your country assigns to something else.

Range and speed: what to expect

The Wi-Fi Alliance quotes about 1 km for HaLow. That figure is a fair middle. With antennas mounted high and a clear view, vendors have shown links of several kilometers. Inside a building with concrete floors, expect hundreds of meters or less, which is still several times what 2.4 GHz manages through the same walls.

Speed depends on channel width and signal strength, and the two pull against each other. Close to the access point on a wide channel, a HaLow link can carry tens of megabits per second, enough for a video camera. At the edge of range the link drops to its slowest coding, around 150 kbit/s, which is still plenty for sensors, door controllers and meters. Plan around the speed you need at the furthest device, not the headline figure.

All devices on one access point share the airtime. A few cameras streaming continuously will use most of it; hundreds of sensors sending a reading a minute will barely register.

How HaLow saves battery

Normal Wi-Fi is hard on batteries because a device has to wake often to stay connected. HaLow was designed with sensors in mind and includes:

• Target wake time (TWT). The device and the access point agree when the device will next wake, so it can sleep for long, scheduled periods and skip the frequent check-ins. TWT later spread to Wi-Fi 6.
• Restricted access windows. The access point can give groups of devices their own time slots, so thousands of devices do not all try to talk at once.
• Short frames. Smaller headers mean less time with the radio on for each small message.

The Wi-Fi Alliance describes battery life of months to years on a coin cell for suitable devices. That holds for a sensor that wakes, sends a reading and sleeps. A camera or anything that streams needs mains or a large solar setup, as it would on any radio. The powering IoT sensors guide shows how to work out a real battery budget.

How a HaLow network is built

A HaLow network looks like any small Wi-Fi network with a longer reach.

The access point. A HaLow access point, mounted as high as you can and cabled to your router or switch. Some products combine a HaLow access point with a normal Wi-Fi router.

Clients. Devices with a HaLow radio built in: cameras, sensors, gate and door controllers, development boards and modules.

Bridges. A small box that talks HaLow back to the access point and offers ordinary 2.4 GHz Wi-Fi or an Ethernet port at the far end. This is the most common use today, because it lets existing Wi-Fi devices work in a shed or a gatehouse with no HaLow radio of their own.

Up to 8,191 devices can associate with one access point under the standard, far more than a home Wi-Fi router handles. Real limits come from airtime and the access point’s own hardware.

HaLow compared with the alternatives

Against 2.4 GHz Wi-Fi. HaLow wins on reach and battery life and loses on speed and on choice of devices. Inside one house, 2.4 GHz with a mesh system is simpler and cheaper; our 2.4 vs 5 GHz guide covers that case.

Against LoRaWAN. LoRaWAN reaches further and runs sensors for longer, but it moves only tiny payloads and cannot carry video, firmware images or a web interface without great difficulty. HaLow moves real data and speaks IP, so a camera, a gate controller and a sensor can share one network. If every device sends a few bytes and the site is huge, choose LoRaWAN. If some devices need bandwidth or you want plain IP everywhere, HaLow is the better fit.

Against cellular. Cellular needs no infrastructure of your own and works anywhere the operator does, at the cost of a subscription per device. HaLow suits a property you control, where you can put up one access point and pay nothing per device afterward. The NB-IoT vs LTE-M guide covers the cellular side.

Against Zigbee, Z-Wave and Thread. Those are low-power mesh networks for inside a home. They reach further by hopping between devices and need a hub or border router to join your IP network. HaLow covers distance in one hop and needs no translation. They are not really rivals: one serves the house, the other the grounds.

Where HaLow fits

• Farms and large properties: water tank levels, gate status, soil sensors, a camera at the far boundary.
• Warehouses and yards: sensors and scanners spread across a big building or an outdoor lot.
• Outbuildings: a bridge that brings ordinary Wi-Fi to a garage, workshop or guest house without running cable.
• Industrial sites: reaching equipment through steel and concrete where 2.4 GHz fails, while keeping IP networking for the gateway and the dashboard.
• Smart cities: street-level sensors and cameras on one network, which is where several chip makers are aiming next.

It is a poor fit inside an ordinary home, where 2.4 GHz and a low-power mesh already work, and anywhere you need many devices from many brands today, because the product range is still small.

Before you buy

• Check the region. The hardware must be certified for your country’s sub-1 GHz band.
• Look for Wi-Fi CERTIFIED HaLow. Certified products have been tested to work together and support WPA3, the current Wi-Fi security standard. Uncertified gear may only talk to its own brand.
• Plan the access point’s height. Height and line of sight do more for range than anything else you can buy.
• Size for the furthest device. Work out the speed that device needs at the edge of range, not the speed next to the access point.
• Secure it like any network. HaLow devices are network devices, so the IoT security basics apply: change default passwords, keep firmware updated and consider putting them on their own VLAN.

For the other ways to connect devices over distance, see the LoRaWAN guide, the IoT protocols overview and the rest of the connectivity guides.