In just 15 years, WiFi has evolved from a sluggish technology to one that’s robust and versatile. And because it now plays an integral role in the lives of hundreds of millions of people, it is being improved almost constantly. But will these changes bring about the two most important things consumers and companies are looking for: range and speed?
There are three recently-adopted WiFi standards that have been created to reach these goals. But before we take a closer look at these standards, let’s step back and briefly review IEEE standard history. The Institute of Electronics and Electronics Engineers is a professional association that acts as an authority for electronic communication. The IEEE creates standards and protocols for communication in industries like telecommunications and information technology. Each standard the IEEE ratifies is designated by a unique number. 802 is the prefix used for any protocol or amendment that entails area networking. For instance, standards for ethernet local area networks (LANs) are designated by 802.3, and Bluetooth personal area networks (PANs) are designated by 802.15. Wireless LANs—the subject of this article—are designated by 802.11.
Which wireless technology is best suited for your IoT application? Download this white paper to find out!
In 1997, the IEEE released the base standard for wireless local area network (WLAN) communications, which they called called 802.11. In the years following, many amendments were made to this standard.
Here we’ll focus on three recently-created WiFi network options:
- 802.11ah (HaLow), created for low data rate, long-range sensors and controllers.
- 802.11af, created for applications similar to HaLow. (This network option relies on unused TV spectrums instead of 2.4 GHz or 5 GHz bands for transmission.)
- 802.11ad, created for multigigabit speeds (sans wires) and high-performance networking.
After a thorough introduction to these three standards, we’ll review the rest of the 802.11 family.
The majority of WiFi standards—including A, B, G, N, and AC—operate at either 2.4 GHz or 5 GHz. And with this relatively high data rate comes lower sensitivity. So if you have a WiFi-connected thermostat on the second floor of your building and a WiFi router in the basement, the thermostat it could really struggle to connect if you’re using traditional 802.11n.
To increase the relatively short range of WiFi—specifically for IoT sensors that don’t require high data rates—802.11ah was introduced. HaLow (as it’s nicknamed) is 900 megahertz WiFi, meant for long-range data transmission.
HaLow also theoretically addresses low power consumption. For example, HaLow uses target wake time to reduce the amount of energy a device needs to stay connected to the network. It does this by having devices wake up for very short times at defined intervals—say, for milliseconds every 15 seconds—to accept messages. This is similar in concept to how eDRX works to help LTE-M save power.
Who could use HaLow:
- Companies using sensor-level technology that needs to be WiFi-enabled.
- It penetrates through walls and obstructions better than high frequency networks like 802.11ad, which we’ll discuss below.
- It’s ideal for short, bursty data that doesn’t consume a good deal of power and needs to travel long distances—think smart building applications, like smart lighting, smart HVAC, and smart security systems. It would also work for smart city applications, like parking garages and parking meters.
- There is no global standard for 900 MHz. Right now, 80% of the world uses 2.4 GHz WiFi, which means you can connect on these global standard bands anywhere in the world. But because there isn’t a global standard for 900 MHz, HaLow is very U.S.-centric.
- AH is available, but isn’t being used. HaLow was released in 2016 but there isn’t presently a single product on the market that uses this standard. This may be due in part to the lack of a global standard, but it is likely also due to the fact that there are competing technologies on the market that better address the needs of IoT. For example, Symphony Link has an even lower data rate, which increases the link budget. This means you’ll get better penetration than you theoretically could with 802.11ah. Symphony Link and technologies like it also don’t have nearly the same IP overhead. HaLow needs to support IP traffic, but Symphony can address TCP/IP traffic over the air.
802.11af utilizes unused television spectrum frequencies (i.e. “white spaces”) in UHF and VHF to transmit information. Because of this, it’s earned the nickname “White-Fi.” Because these frequencies are between 54 MHz and 790 MHz, AF can be used for low power, wide-area range, like HaLow.
802.11af was released in 2014, but never really took off for several reasons. First, there are many complexities around geolocation. For example, if you are located in California, you may be allowed to use a certain UHF channel because it’s available in your area—but if you travel to D.C. and try to use the same channel, a broadcaster there may already own the license. Additionally, radio front ends have to be specifically designed and filtered to work across hundreds of MHz of UHF spectrum. This means you’re never going to be able to buy equipment that can access all of these channels without paying hundreds or thousands of dollars.
Who could use it:
- Organizations that need extremely long-range wireless networks.
- Because AF can utilize several unused TV channels at once, it works well for very long range devices—potentially up to several miles—with high data rates.
- Requires expensive, band-specific hardware.
- “White space” channels are not available everywhere, particularly big cities.
- Like HaLow, 802.11af is not a global standard—it is U.S./Canada specific. And because the certification of spectrum is a country-by-country process, device manufacturers aren’t likely to add AF into their device unless they have to.
802.11ad couldn’t be more different from AH. While AH is a potential low-power, wide area network (LPWAN) option, AD is 60 GHz WiFi ideal for very high data rate, very short range communications. In fact, AD is meant to be a fiber optic replacement that can achieve speeds 50 times faster than 802.11n.
AD hasn’t taken off simply because it has such a narrow market. Not very many people require multi-gigabit speeds in very small networks except those who need to wirelessly stream raw video.
Who could use it:
- Enterprise-level organizations that need extended bandwidth with very short-range devices, like wireless raw video streaming.
- Good for high data rate file transfers and communication. At 8 gbps, AD is 50 times faster than 802.11n (which was regarded as the fastest protocol yet when it was introduced in 2007). In fact, this protocol is so fast that, according to this Fast Company article, AD has the potential to “enable a whole new class of devices,” like “wireless hard drives that feel as fast as locally connected ones.”
- The chips are very expensive to manufacture, which makes this a costly set up.
- AD provides a very short range. When you have a really high frequency like 60 GHz, short-range communications are ideal. This isn’t a problem if you have the router right next to you. But if you to penetrate walls, you’ll need additional routers.
- AD is not a recognized international standard.
- There is very little need for the kind of speed offered by 802.11ad. For the most part, highly-compressed video sent over normal WiFi (i.e. as Apple Video and Chromecast do) is good enough for the majority of consumers.
Additional Past & Current 802.11 Amendments
Graphic courtesy of Microwaves & RF
802.11a (1990): “WiFi A”—also known as the OFDM (Orthogonal, Frequency Division Multiplexing) waveform—was the first amendment, coming two years after the standard was complete. This amendment defined 5 gigahertz band extensions, which made WiFi A more flexible (since the 2.4 GHz space was crowded with wireless home telephones, baby monitors, microwaves, and more).
802.11b (2000): As one of the first widely used protocols, “WiFi B” had an improved range and transfer rate over 802.11a, but it is very slow by today’s standards (maxing out at 11 mbps). 802.11b defined 2.4 GHz band extensions. This protocol is still supported (80% of WiFi runs off 2.4 GHz), but the technology isn’t manufactured anymore because it’s been replaced by faster options.
802.11g (2003): “WiFi G” came onto the market three years after B, offering roughly five times the transfer rate, at 54 mbps. It defined 2.4 GHz band extensions at a higher data rate. Its primary benefit was greater speed, which was important to consumers. Today, however, these speeds are not fast enough to keep up with the average number of WiFi-enabled devices in a household or a strong wireless draw from a number of devices.
802.11n (2007): “WiFi N” offered another drastic improvement in transfer rate speed—300-450 mbps, depending on the number of antennas—and range. This was the first main protocol that operated on both 2.4 GHz and 5 GHz. These transfer rates allowed large amounts of data to be transmitted more quickly than ever before.
802.11ac (2013): In 2013, “WiFi AC” was introduced. AC was the first step in what is considered “Gigabit WiFi,” meaning it offers speeds of nearly 1 gbps, which is equivalent to 8000 mbps. That’s roughly 20 times more powerful than 802.11n, making this an important and widely used protocol. AC runs on a 5 GHz band, which is noteworthy—because it’s less widely used, you’ll have an advantage as far as speed is concerned, though the higher frequency and higher modulation rate mean the range is more limited. In 2016, amendments were made to AC to improve its performance.
Where do you see WiFi heading?
Two years ago, we believed that HaLow, AD, and AF were clear evidence that WiFi had undergone a spectacular transformation—but we also expected that all three protocols would be widely used after their release. Turns out, their adoption has been anywhere from low to nonexistent. The IEEE still reviews amendments to the 802.11 protocol regularly, so we’re interested to see what happens over the next few years!