Humans aim high, they plan to turn Mars into a home and desire to bring interconnection between people and people, people and objects, and objects and objects. This interest in connecting all things has led to the conception of IoT. Clearly, IoT is a game-changer, its rapid growth sparked a transformation in numerous technologies including, wireless networks. How then, has the Wi-Fi industry adapted to meet the requirements of the wireless connections between these many IoT devices? The answer is a single protocol: Wi-Fi HaLow (aka IEEE 802.11ah), a Wi-Fi standard specifically created to efficiently meet the challenging requirements of IoT.
What is Wi-Fi HaLow and Why it’s beneficial to IoT?
Wi-Fi HaLow (pronounced Hey-Low) is a low-power, wide-coverage version of the traditional Wi-Fi standard, which supports low-energy communication of a high number of IoT devices within a large area. It was launched in 2010 by IEEE and officially released by Wi-Fi Alliance on May 10, 2017. This standard was developed because traditional Wi-Fi has a short effective distance, high power consumption and it puts a limit to the number of devices that can be connected to a single access point. All these attributes are undesirable, and they act as big roadblocks in IoT’s path to success. You can also check out LoRaWAN Technology which is also a very promising wireless protocol, popularly used in long-range IoT devices. The table given below shows the difference between normal Wi-Fi and Wi-Fi HaLow for comparison.
On the other hand, the Internet of Things (IoT) is a big fan of the HaLow standard as it offers low power consumption, a wide coverage area, and allows multiple access nodes. These features satisfy the key requirements needed for the success of IoT connectivity and applications.
IoT networks consist mostly of sensor nodes powered with batteries. Stretching the energy in the network to last for as long as possible is crucial. This is why Wi-Fi HaLow introduced a new channel access technology called Restricted Access Window (RAW). RAW divides the sensor nodes into groups, and it assigns each group time intervals called RAW slots. During a RAW slot, a group is awake and has a data transmission opportunity. When the assigned RAW slot ends, the sensor nodes go to sleep and save energy. Take, for example, smart cities, where there are hundreds of sensors, including those to facilitate smart parking, ease traffic congestion, measure electromagnetic field levels, and waste management. Not properly managing the energy resource in this big family of sensors could lead to the failure of IoT’s mission of turning dumb cities into smart ones that improve the quality of lives of their habitats.
Currently, the Wi-Fi enabled devices in the market operate in the 2.4 GHz and 5 GHz ISM (Industrial, Scientific, Medical) spectrum bands. These spectrums are already saturated since almost every device in today’s era is Wi-Fi enabled. Further overcrowding of this spectrum with IoT devices results in nothing but interference, data loss, and low data rates. According to Wi-Fi Alliance, the HaLow standard operates in the underutilized sub 1 GHz (S1G) meaning it uses carrier frequencies below 1 GHz in the ISM band. It also uses narrower channels to provide better building penetration and to offer up to a 100 times longer range than other IoT technologies. This extends connectivity to even hard-to-reach places like garages, basements, and large outdoor areas.
Wi-Fi Alliance also notes that Wi-Fi HaLow supports a native IP architecture, meaning there is no need for proprietary switches or hubs. This native IP support feature makes the system easy to expand and less complex. All these advantages are too great to ignore.
Challenges Faced by Wi-Fi HaLow
There are different sub 1 GHz ISM bands available for the 802.11ah standard in different countries. The US proposes support to channels with bandwidths of 1, 2, 4, 8, and 16 MHz in the sub 1 GHz spectrum. This, however, is not ideal for other countries that have a small number of channels supported at 1 MHz and others like China, where most of the sub 1 frequencies are already being used for TV broadcasting. The variation in frequencies amongst countries makes it difficult to produce Wi-Fi HaLow products that work universally.
Channelization of 802.11ah in different countries
|
Country |
ISM frequency Band (MHz) |
Channel Bandwidth (MHz) |
|
United States |
902 - 928 MHz |
1, 2,4,8, 16 MHz |
|
South Korea |
917.1 - 923.3 MHz |
1,2,4 MHz |
|
Europe |
863 - 868 MHZ |
1,2 MHz |
|
China |
755 – 787 MHZ |
1,2,4,8 MHz |
|
Singapore |
920 – 925 MHz |
1 MHz |
Applications of Wi-Fi HaLow
Chips and systems using the .11ah standard are expected to integrate the market in 2021. Quite a number of the world’s largest companies have been working on this technology, including, Qualcomm, Intel, Mediatek, Broadcom, LG, ZTE, and Samsung.
Since the standard offers a large coverage, it is expected to be used in rural communication. To bring life to services such as E-Health and E-Learning in rural areas. This all falls under the intent of “connecting the unconnected”, and pushing technology to even the outskirts of urban areas so that it can benefit all of humanity. Another use case is sensor networks, mainly because the standard allows more sensors to be connected per access point and it has an increased penetration through walls and obstructions.
Cellular traffic off-loading, sensor network backhauls, smart homes, smart cities, battery-powered agriculture and environment sensors, surveillance systems, process control sensors, and many others will use this technology. Use cases for the HaLow standard in IoT systems are broad because it combines security, scalability, and energy efficiency to address many IoT applications in multiple industries.
Summary
Wi-Fi HaLow (pronounced Hey-Low), is basically an optimized form of Wi-Fi for IoT applications. It offers a low-power consumption, a wide-coverage, and an increased number of nodes per access point. In this section, we compared its features with those of traditional Wi-Fi, its design challenges, use cases and discussed why it is beneficial to the IoT community. Have any questions related to the topic? Feel free to leave a comment below.
