802.11ah Emerges to Connect the Internet of Things

By mverbloot posted Feb 17, 2016 07:26 AM


There’s a lot of excitement in the industry about the Internet of Things (IoT). The global market will grow to $1.7 trillion in 2020—up from $655 billion in 2014, according to IDC.


Smart light bulbs, thermostats, health monitors, countless other devices, and sensors promise to make our homes, cars, cities, factories and farms more efficient. But first, the network needs to be ready for the unique demands of IoT.  


To help businesses meet the challenges of connecting trillions of sensors and devices, a new wireless technology defined by the Wi-Fi Alliance has emerged—802.11ah—or Wi-Fi HaLow.  


Enter 802.11ah

If you’ve tried deploying sensors or IoT with existing Wi-Fi technology, you know it’s hard. The current Wi-Fi technology doesn’t lend itself to long battery life, long distances or a large number of devices connected to an access point (AP).


802.11ah is designed to overcome those challenges. It is designed for:


  • Large scale. The latest Wi-Fi standard effectively delivers a tenfold increase in the number of devices supported by each AP. A typical 802.11ac or 802.11n AP supports 255 devices while an 802.11ah AP can support up to 2,000 devices.


  • Long-range, low power connectivity.11ah operates in the 900MHz band. Lower power means greater range—and 802.11ah can go nearly double the distance than today’s Wi-Fi technologies. It can transmit up to 1 kilometer with a robust signal that can penetrate walls, floors, and other obstacles.


  • Short, bursty machine traffic. The tradeoff for the longer distance and low power is capacity. 802.11ah has 26 channels but are only 1MHz wide. Two channels can be bonded for 2MHz channel width. It’s significantly less than 802.11ac or 802.11n, but it’s plenty for sensors and other machine-to-machine communications. Expected transmission speeds are from a minimum of 150Kbps to tens of Mbps. They will be short and bursty in nature helping preserve battery life of the IOT device.


802.11ah also supports a relay mode meaning that an 802.11ah device can relay data to another 802.11ah device further away – sort of like mesh Wi-Fi except it is not the Access Points performing the mesh but the clients themselves. In this mode, the maximum distance between a client and 11ah AP could be tripled as relay mode is limited to a maximum of 2 hops. Another interesting aspect of relay mode is that the closer device will transmit at a higher MCS (transmission rate) to the AP than the device it is relaying. So whilst the transmission speed reduces the further out you go that does not impact devices directly connected to the access point as they always transmit at a higher rate. This is a smart way to improve the efficiency of the IOT system.


 We may see new access points supporting 802.11ac and 802.11ah although running at 900MHz will mean larger antennas than 2.4GHz and 5 GHz access points potentially increasing the physical size of an AP.


802.11ah is preceded by other low-power connectivity choices for machine-to-machine communications. These earlier technologies are largely in the category of personal area networks (PANs), so they have more limited range. These include Bluetooth Low Energy (BLE), 802.15.4 ZigBee and ZWave. For example, ZigBee, which is used in many home automation products today like Nest, has a range of just 10 to 30 meters, a maximum speed of 250 Kbps, and there can be interoperability issues among ZigBee devices. 


Get Ready Now

IoT is on the precipice of exploding growth. IoT is where the cloud market was five years ago when few organizations truly understood the transformative value. We’re looking at the infinite possibilities of delivering business value with machine-to-machine communications.


While 802.11ah is working its way through the standards process, now is the time for network architects to get ready. The final 802.11ah standard is expected to be ratified at the end of 2016, with products certified Wi-Fi HaLow by the Wi-Fi Alliance to follow.


Start now by getting a deeper understanding of the new Wi-Fi technology, whether you are planning to automate your own home or are exploring it for use in retail, healthcare, manufacturing, or another industry.



Feb 26, 2016 05:19 PM

I agree, that IoT is ready to explode. It's been boiling for years in various forms, but this may be the catalyst for super expansion. I see opportunity, lots of opportunity.

Feb 17, 2016 11:34 AM

Excellent article! Thank you!