November 2, 2021, stands out as a momentous day for the ever-evolving Wi-Fi standard. That’s when the Wi-Fi Alliance introduced its Wi-Fi Certified HaLow program for products based on the IEEE 802.11ah standard. Wi-Fi HaLow is the first Wi-Fi standard tailored to meet the needs of the Internet of Things (IoT), making it a superior alternative to traditional Wi-Fi competitors as well as Low-Power Wide Area Network (LPWAN) solutions such as LoRaWAN, Sigfox and Narrowband IoT (NB-IoT).
Wi-Fi HaLow offers a unique combination of advantages that other wireless protocols can’t match:
- It’s compatible with all other Wi-Fi variants and natively supports Internet Protocol (IP).
- It consumes very little power with efficient sleep and power management modes, enabling multi-year battery operation for IoT devices.
- It can serve more than 8,000 nodes from a single access point.
- Operating in the unlicensed industrial scientific and medical (ISM) bands below 1 GHz (850 MHz to 950 MHz globally and 902 to 928 MHz in North America), it can span long distances beyond 1 km — well beyond the reach of traditional Wi-Fi protocols.
All other versions of Wi-Fi operate at either 2.4 GHz, 5 GHz, 6 GHz or a combination of these frequencies, but since Wi-Fi HaLow uses sub-GHz frequencies and has a much narrower channel bandwidth, it offers 10 times their range. That’s because the narrower the channel, the greater the range, and the lower the frequency, the better the penetration through walls and other obstacles. In addition, the Wi-Fi HaLow protocol added a range-optimized modulation and coding scheme (MCS10) that also helps boost link budget. Collectively, these capabilities give Wi-Fi HaLow up to 24 dB of link-budget improvement versus IEEE 802.11n (Wi-Fi 4).
These and other features make Wi-Fi HaLow well suited for a wide range of IoT applications including smart factories, building automation, warehouses, smart city infrastructure, transportation and fleet management, telemedicine and many other remote monitoring applications. Rather than having to deal with multiple connectivity standards, Wi-Fi HaLow can serve every LED bulb, light switch, smart door lock, motorized window shade, thermostat, smoke detector, solar panel, security camera or any other imaginable smart home device. In industrial IoT environments, Wi-Fi HaLow can support many diverse types of sensors and other wireless devices connected to machines that must communicate their data to the Internet and potentially to a cloud data center.
Wi-Fi HaLow is designed to serve IoT sensors and other devices that require exceptionally low levels of DC power, many of which must operate from a small battery for many years. Although the standard’s maximum data rate is only 43.3 Mb/s for 8 MHz channels, that’s more than adequate for nearly every home automation and industrial IoT device, as well as high-resolution cameras streaming high-definition video.
To achieve this combination of energy efficiency and optimal throughput, Wi-Fi HaLow has a variety of advanced sleep modes that allow connected devices to remain in a low-power state for extended periods of time. For example, target wake time (TWT) makes it possible for nodes to negotiate with an access point and set predetermined times when each node will wake and listen for beacons, yielding longer sleep durations to conserve battery life. The standard also supports a restricted access window (RAW) capability where the access point can divide the available bandwidth across multiple groups of nodes, enabling specific numbers of nodes to transfer data while others remain in sleep mode. These and other energy-saving capabilities make it possible for power-constrained IoT devices to optimize their battery life. Fully integrated Wi-Fi HaLow system-on-chip (SoC) solution like the one offered by Morse Micro, integrates a radio, PHY, media access control (MAC), power management unit (PMU) and other host interfaces into a single, small-form-factor chip which helps reduce the overall solution size.
Like all versions of Wi-Fi, HaLow can automatically scale its bandwidth and data rates depending on signal integrity and distance from the access point using multiple MCS levels from 150 kb/s to 40 Mb/s for a single-stream, single-antenna device using channel widths ranging from 1 to 8 MHz.
Wi-Fi HaLow supports multiple MCS schemes including binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), and 16 to 256 quadrature amplitude modifications (QAM). Depending on the MCS scheme used, Wi-Fi HaLow data rates vary from 150 kbps using MCS 10 with BPSK modulation to a top rate of 40 Mbps using MCS 9 at 256 QAM. Two spatial streams using 8 MHz channels top out at 87 Mbps, and there are options to use even higher numbers of spatial streams for applications that require even higher data rates.
While Wi-Fi HaLow is the most feature-rich, all-encompassing Wi-Fi standard to date, addressing a broad spectrum of IoT applications, this does not mean that it will supersede all other Wi-Fi variants in all use cases — and it’s not intended to do so. For example, data-intensive applications such as high-end gaming, ultra-high resolution video streaming, and low-latency virtual and augmented reality still require blazingly fast data rates offered by higher frequency forms of Wi-Fi that are shorter in range and more power hungry than Wi-Fi HaLow.
What Wi-Fi HaLow does best is to address the unique requirements of IoT connectivity by serving thousands of IP-capable devices over long distances while reducing power consumption to miniscule levels that extend battery life. Other forms of Wi-Fi were never designed to meet these disparate needs, and no other wireless protocol can match these combined advantages for IoT applications. Wi-Fi HaLow is changing the paradigm for standards based IoT connectivity for the first time and is reinventing how we communicate wirelessly with billions of IoT devices, now and for years to come.