Wi-Fi HaLow

In the connected world we all live in, Wi-Fi has become one of the main technologies for wireless short haul and indoor communications. However, a Wi-Fi wireless protocol that is yet to receive widescale adoption is Wi-Fi HaLow (pronounced halo). This uses 900MHz Radio Frequency (RF) bands to provide longer range, compared to the conventional Wi-Fi networks operating in the GHz frequency bands. It also has low energy consumption and can support higher data rates and wider coverage than other radio protocols.

Long distance

Conventional Wi-Fi provides very good data transfer rates (Mbps), but operating at RF bands of 2.4GHz, 5GHz, or 6GHz, Wi-Fi can suffer from poor propagation and interference from other devices. LoRa (Long Range) technology is capable of communications over several kilometres, but has a limited data packet size and a low data rate (kbps). Wi-Fi HaLow can provide Mbps data rates and over distances of several kilometres.

In radio, higher radio frequencies systems cannot communicate over longer distances when compared to lower frequency systems. So 900MHz Wi-Fi HaLow can communicate over longer distances than conventional Wi-Fi which uses GHz frequencies, and it can propagate more easily through walls and reach devices that reside further away (at least double the range of 2.4GHz Wi-Fi and even more than 5/6GHz Wi-Fi), all while requiring significantly less power. In January, The Morse Micro team (which includes the original inventors of Wi-Fi and designers of Wi-Fi chips) staged a record-setting field test of a long-range video call over 3km.

Another advantage of Wi-Fi Halow for rail is that the GSM-R system also uses frequency channels around the 900MHz band, so the lineside GSM-R mast sites could also possibly support Wi-Fi HaLow for trackside data communications.

Low powered

Wi-Fi HaLow is designed to meet the requirements of smart devices because of its ability to operate using very low power, penetrate through walls, and operate at significantly longer ranges than conventional Wi-Fi. It should enable applications from small, battery-operated devices to large-scale deployments. The Morse Micro team says Wi-Fi HaLow chip’s power requirement could be under 0.25mW. This would provide a battery lifetime of one month from a CR2032 coin cell or years from two AA batteries, and the charging for rechargeable batteries could probably be sourced from solar power.

ow in 2017 as 802.11ah, based on the 802.11 2007 wireless networking Standard. It has a theoretical data rate of up to 86.7Mbps and can operate with 1, 2, 4, 8, and 16MHz channels. It also uses modulation and coding schemes that can accommodate different RF conditions and distances between devices, including the use of repeaters.

According to the Wi-Fi Alliance, Wi-Fi HaLow is an open standard which can co-exist with Wi-Fi 4, Wi-Fi 5, Wi-Fi 6/6E, and Wi-Fi 7 networks without suffering RF interference. It also supports IP and complies with the WPA3 wireless security encryption algorithm. Power-saving features include Target Wake Time (TWT) and Restricted Access Window (RAW), to reduce channel contention and minimise power consumption, by ‘sleeping’ for long periods of time or in between predictable activity patterns.

Adoption

Despite the advantages of Wi-Fi HaLow, adoption has so far been slow. It would appear that there are only so many Wi-Fi chip designers in the world and a lot of effort has gone into Wi-Fi 6 and Wi-Fi 7. The big companies need to target their resources where they make their best revenues, and while producing around 4 billion Wi-Fi chips annually, they cannot yet focus their resources on producing another RF Wi-Fi chip. This may change though.

The availability of sub-GHz spectrum for Wi-Fi HaLow also varies around the world. There’s a lot of spectrum available in the US but not in Europe. A particular problem for the UK is that Ofcom has already allocated 900MHz band licences to Mobile Network Operators (MNOs), which currently leaves very little unlicensed spectrum for Wi-Fi HaLow. This limits the spectrum for HaLow and data speeds are said to start at around 150kbps, rising to a few Mbps. Ofcom has been known to take back spectrum from MNOs, but would the MNOs provide a Wi-Fi HaLow service using their licenced spectrum? This is unlikely, but we will have to see what develops.

When it is available, Wi-Fi HaLow is predicted to be more robust and reliable than normal Wi-Fi and it should work well in dense environments. This could be an entire station, office, or warehouse. With Wi-Fi HaLow in outdoor environments, multiple kilometre ranges with Mbps data throughput should be possible, making it ideal for rail.

The Wireless Broadband Alliance (WBA) announced in January that its Wi-Fi HaLow for IoT programme has moved into a new phase and this year it will showcase its Wi-Fi HaLow solutions in real-world use cases. These include applications including Smart Home, Smart City, Smart Building Automation, Smart Retail, Industrial IoT and Agriculture Technology.

In the coming months, the project team will test the use cases and applications to demonstrate the benefits and performance of Wi-Fi HaLow, including understanding coverage areas, data rates, throughput, and signal reliability. The analysis from the trials will inform new deployments and help the wider industry to roll-out IoT solutions. The trials will include:

• Smart Home – Evaluating Wi-Fi HaLow against traditional Wi-Fi security cameras, Heating, Ventilation, and Air Conditioning (HVAC) appliances, detached garage connections, solar power systems, power backup generators, and electric vehicle chargers.
• Smart City – Focusing on infrastructure monitoring, smart utilities and traffic management, high data throughput, increased device density and low-cost maintenance.
• Smart Building Automation – Conduct testing to support smart building applications such as physical security, surveillance, access control, safety alarms, and water sensors.
• Smart Retail – To showcase how Wi-Fi HaLow could enhance consumer satisfaction and increases productivity for retailers. The assessment will cover scanners, readers, point-of-sale equipment, asset tracking, security monitoring, warehouse robots, and handlers.
• Industrial IoT – A focus on testing industrial applications including asset tracking, infrastructure monitoring, remote equipment control, safety automation, and security monitoring. This will benefit the rail industry.
• Agriculture Technology – Trials in smart agriculture or precision farming systems, including environmental monitoring, soil monitoring, plant health monitoring, actuator control, and data collection for predictive breeding.

Conclusion

It’s likely that Wi-Fi HaLow will gain adoption in the coming years. Already there are outdoor security battery-powered AI-enabled smart cameras capable of working over distances of several km being developed, and other rail applications could include CIS and PA systems and Internet of Things (IoT) sensors for all types of assets. Wi-Fi HaLow is unlikely to replace conventional Wi-Fi devices, but it should create new applications with designers being able to put devices and sensors in places, and with data throughputs not possible today.