The WiFi Alliance has released a new standard for wireless communications that acknowledges some basic facts about radio communications that have frustrated users for years.
Those basic facts involve the distance and building penetration capabilities of 2.4GHz WiFi and, to an even greater extent, 5GHz WiFi. The bottom line is that WiFi has some pretty short ranges and doesn’t go through walls very well.
The new 900MHz standard uses frequencies that eliminate some of those problems, but as you might expect, will introduce some problems of their own. The unlicensed part of the 900MHz frequency band is shared by a number of licensed services, including private land mobile communications, some types of medical equipment and amateur radio, all of which operate in the 902–928 band planned for what the WiFi Alliance is calling HaLow, but which is really called 802.11ah.
In addition to the licensed services, other unlicensed services, including NCR WaveLAN, occupy this section of radio spectrum. WaveLAN is the predecessor of WiFi and was used in much the same way. I first reviewed WaveLAN for Byte magazine long ago, and while you might think it’s obsolete to the point of extinction, it’s still being used.
The advantage to WiFi users is that 900MHz is such a low frequency that it exhibits propagation characteristics more akin to radio waves than what you find in the microwave regions above 1GHz. While 900MHz is still only suitable for line-of-sight communications, it has excellent range, and it will go through walls far better than WiFi has in the past.
The ability to cover longer distances also translates into the ability to use lower-power transmitters, which is vital to Internet of things (IoT) devices that may have to run for long periods of time on batteries.
In addition to supporting devices that can use lower transmission powers, HaLow devices are assigned channels with less bandwidth than usual. Some of those data channels only provide 1MHz bandwidth allocations, which translates into data rates as low as 150K bps.
Those low data rates aren’t going to do you a lot of good for streaming movies from NetFlix, but they are more than adequate for machine-to-machine communications as well as for telemetry and smart devices. For now, the largest channel size that the WiFi Alliance is certifying is 4MHz, which can provide a data rate of 18M bps.
While this might seem like a step back from the WiFi Alliance’s previous efforts to get wireless communications above gigabit speeds, in fact, it’s a smart step to put lower bandwidth networks into place where high speed isn’t needed.
HaLow WiFi Standard Brings Its Own Set of Highs and Lows
It’s also smart to enable greater distance and reliability for communications needs that can use those lower speeds. A good example might be HaLow for a smart thermostat so that it’s reachable throughout an entire house
Unfortunately, the new HaLow standard doesn’t have its frequencies to itself. Because the 900MHz band is shared with other licensed services, the new WiFi band is subject to interference from other users and there is no remedy when that interference happens.
For example, if a ham radio operator next door goes on the air with a powerful signal that wipes out your smart thermostat, you’re out of luck. Because you’re an unlicensed service, you’re required to accept that interference.
However, if your smart thermostat happens to cause interference to that ham radio operator next door, then you’re required to stop doing it. As an unlicensed user, you have few rights to the spectrum if someone else wants to use it.
Fortunately for future users of the HaLow standard, 900MHz isn’t a busy band. While this band isn’t heavily used by amateur radio operators, there are a lot of land mobile users, especially in large cities and HaLow can’t interfere with those users either. So while there will be times when WiFi users will be required to give way to licensed users, this probably won’t occur frequently.
If you’re contemplating commercial use of HaLow WiFi for your business, the limitations of this band will matter to you, depending on how it’s used in your area. You will need to be prepared for the possibility that there may be places where you can’t use 802.11ha because other services are creating too much interference. There’s no help for that. You’re going to have to find another frequency or another business model.
Fortunately, there are options. While the 2.4GHz band might not be ideal for what you have planned for lower frequencies, it’s still there and doesn’t share some of the limitations of 900MHz, such as a lot of licensed users that you must share with.
The new standards for 900MHz are a welcome addition to the WiFi world, and because the WiFi Alliance will be certifying tri-band devices, future WiFi devices should have added flexibility. While the new frequencies won’t do anything to help with big entertainment downloads, it will provide a new doorway into important new uses for wireless.