With the addition of billions of low-power devices to the Internet of Things, how will they communicate? The Wi-Fi Alliance have been developing IEEE 802.11ah, dubbed HaLow, to satisfy connectivity requirements of IoT. This post looks at what you need to know about HaLow.
HaLow (pronounced “halo”) transmits data on the 900 megahertz Wi-Fi spectrum. It is designed to be the standard for connectivity for IoT in the home, on wearables, in the connected car, as well as in other IoT environments such as smart cities, industrial, retail and agricultural settings.
HaLow provides the following benefits:
- Low power usage. Sensors, wearables, and many other IoT devices have insufficient power to transmit on the traditional Wi-Fi spectrums of 2.4 GHz and 5GHz. However, low frequency transmission, such as HaLow’s 900 MHz Wi-Fi uses only a fraction of the power of our current Wi-Fi bands. Low-power IoT devices can connect through HaLow.
- Obstacle penetration. Lower frequency waves are better at penetrating obstacles such as walls, floors and trees. Higher frequency waves tend to get absorbed by solid obstacles. We have all noticed how sound travels through walls – the lower frequencies of music, the beat and the bass, penetrate walls far better than the higher notes. In a similar way, we see the same phenomena at sunset where the sun looks red – lower frequency colours (red) are less absorbed by the earth’s atmosphere.
- Long range. Lower frequency waves experience less energy reduction and less dissipation as they pass through air (simply another obstacle). HaLow’s 900 MHz Wi-Fi signals travel roughly twice the distance of conventional Wi-Fi frequencies (some claim HaLow will transmit up to 1 kilometre).
- Traditional Wi-Fi features. These include IP support which enables direct internet connectivity, and some built-in security and interoperability features. HaLow will work with many current devices that use the higher Wi-Fi bands.
The downside of 900 MHz is that it cannot transmit at high data rates. There is a power/data transfer trade-off. Data is transferred at between 150Kbps and 18 Mbps. These low rates are not appropriate for 4K video-streaming for example.
The Wi-Fi Alliance are expected to approve the HaLow standard in mid-2016, however they will only start certifying HaLow products in 2018. The Alliance anticipate HaLow to be the communication channel for devices such as fitness monitors, smart toothbrushes, smart locks, rubbish bins and pot-plant monitors.
As with most new technologies, security is a matter that is likely to only get serious attention after wide-spread adoption of HaLow. Attacks on HaLow networks could be directed against end devices (which are often always-on and unattended and thus susceptible to physical tampering), man-in-the-middle attacks (such as Evil Twin), or against the network router.
Whether HaLow provides the superhighway for IoT connectivity is a moot point – it will take a while to get traction, and there are competing technologies such as Z-wave, Bluetooth, Sigfox, ZigBee which will progress between now and 2018. Li-Fi is also a contender – this technology uses LED light bulbs – capable of transferring data at speeds 100 times faster than conventional Wi-Fi but it suffers the drawback of not going through obstacles (light can’t pass through walls). The technology battle (a-la VHS/Betamax) is yet to be fought for IoT connectivity – time will tell which eventually wins out.