First, a group of student engineers at the University of Washington have released a report that may enable the use of WiFi as the primary method of communicating with Internet of Things devices.
The primary shortcoming of current WiFi technology for IoT is that it is power-hungry. A typical current WiFi transmission between two devices requires a radio at both ends of the transmission path along with a baseband chip that is used to encode the data onto the radio wave. Because the WiFi spectrum is expected to always be busy and have interference, the typical WiFi transmission requires several hundreds of milliwatts of power at each end of the transmission path in order to have a strong enough signal to distinguish it from the background noise from other WiFi signals. And that means that a typical WiFi router is a big user of power in a home.
It is the need for big power that has made it impractical to consider WiFi as the technology for talking to large numbers of tiny IoT sensors in the environment. There is no practical way to power such devices.
The student engineers invented a new type of hardware that uses 10,000 times less power than a traditional WiFi device. They are calling the technology ‘passive WiFi’. The technology uses only one WiFi router in the system that send out signals to the many IoT sensors. Those sensors then mirror the signal back to the transmitting device. In doing so the sensors transmit their current status back to the original router using almost no power – 10 to 50 microwatts. The technique involved takes advantage of what is called frequency backscatter and the whole process uses only a fraction of the full WiFi spectrum.
This technique has a lot of promise. Up until now the best option for talking to small sensors has been Bluetooth. But WiFi spectrum is almost 1,000 times more efficient than Bluetooth and also can include security features that aren’t possible with Bluetooth.
In another breakthrough, Samsung has developed WiFi that can deliver up to 4.6 gigabit speeds using the 60 GHz spectrum. This is the spectrum that is often referred to as millimeter wave radio. Samsung’s breakthrough not only takes advantage of this higher frequency, but the company has also made a breakthrough that allows a data transfer rate that is almost 10 times faster than current WiFi.
This technology means that soon we will have to talk differently about different pieces of the WiFi spectrum. The term ‘WiFi’ is a set of standards that can be applied to many different slices of frequency, but different frequencies have very different operating characteristics.
The 60 GHz frequency cannot pass through walls or almost anything else, and that means that it is going to be used to make very fast wireless data connections within a room. Further, this frequency dissipates very quickly with distance and its effective range is only a few meters, meaning that this frequency will not be usable for outdoor hotspots. It’s a one-room application only. This technology presupposes that a room utilizing it will be connected to fiber.
The antenna array needed for 60 GHz is very different than that used for traditional WiFi and so I am expecting it will be many years before we see too many devices designed to use both regular WiFi and 60 GHz spectrum. It’s more likely until the higher spectrum is widely used that there will be a dongle receiver that you could connect to a laptop or other device.
I would expect the early market for this technology to be applications that need a lot of bandwidth but that don’t lend themselves easily to running fiber. That might mean future virtual reality or augmented reality headsets and systems, factory floors to connect to equipment or in crowded hospital emergency rooms. There are not that many applications today that need more bandwidth than can be supplied by normal WIFi, so expect this to be initially used for those applications that do. But over time there will be more and more real world applications that need more bandwidth and this will be another tool to deliver bandwidth over short distance.