Throughout its more than 20-year existence, WiFi has evolved to be ever faster. That evolution continues but arguably it has already reached a point where home broadband, device processors and other limitations mean that greater speeds are not of benefit to most. So where next, if anywhere, for WiFi?
Of course, the continued success of WiFi is in little doubt. It is in almost every home in the developed world. WiFi chips are embedded in every phone, tablet, laptop and computing device. We send ever-more data each year across WiFi. It has been said that if you want to hold a family conference, go to the room in the house where the router sits, turn it off, and wait a few minutes.
WiFi is central to our lives and will remain so for the foreseeable future. This success brings a constraint to future evolution. We have to keep everything backward compatible and working with the billions of WiFi devices currently out there, so change cannot be too dramatic or rapid. It also means accepting that there may be some older, low-performance devices using an access point at any time, dragging down its overall performance.
One area where WiFi has long striven to improve is automated access. At present we too-often have to select a WiFi base station and enter a password to gain access. Various solutions to this exist, from using the authentication on the cellular SIM card through to completely open systems, but none has enabled simple access to all nodes. Perhaps the best solution is the equivalent of a ‘PayPal for WiFi’ – a trusted third party that signs on to nodes that have registered to it on behalf of users.
Automated access is also a key issue for the Internet of Things (IoT). Imagine trying to tell your washing machine the identity of your home router and then finding a way to enter the password into it using the dial on the front panel. And the toaster is even harder. Again there are solutions to this such as pushing a button on the router at the same time as one on the appliance. It is a good idea, but just not yet quite standardised enough.
A solution as important as WiFi is aiming to play a key role in home IoT applications. This makes sense, in that homes already have WiFi networks and so new devices can be brought into the home and connected without the need for the installation of new home hubs. However, WiFi in its standard form is not ideal for IoT because it requires too much power to be able to deliver the 10-year battery life that many believe is needed for in-home devices that are not mains-powered.
These include concepts like plant moisture sensors and pill-box opening sensors. This is because WiFi is currently optimised for high-speed data transmissions and this requires high-power processors in our devices to decode the data stream as it arrives. We accept the high power consumption this entails because we expect to charge laptops and smart-phones daily. But IoT devices rarely need high speed. Indeed, the plant watering sensors might only send a byte of data a day. That is about one ten millionth of what we might send from our smart-phone.
With those differences in data rates and power consumption requirements, it might seem more sensible to start afresh and design a new technology suited to the IoT that could sit alongside the WiFi router in the home. And indeed, this is a route many have taken. Some solutions are open standard, such as Zigbee, some proprietary such as those used by some smart heating solutions.
However, it is very hard to introduce a new wireless technology into the home – few will want to buy a new home hub just to enable their smart plant sensors. This is why we continue to look to WiFi to evolve a mode suitable for IoT and work is currently underway on variants that are low-power and can work at the same time as conventional WiFi. We will need to replace our home router to get this upgraded capability, but most replace routers fairly regularly, often as part of a change of broadband service or an upgrade to a higher speed broadband solution.
A final issue to address is interference. WiFi nodes can fail to work in dense areas where there are many competing routers all in the same place. Shopping malls, train stations and similar are key examples of this, and the situation is likely to get worse over time as more nodes are deployed and existing nodes are expected to deliver more.
The solution to this is better coordination between nodes. At present, most nodes automatically select the particular frequency they use based on a measurement of the interference across all frequencies. Once the choice is made it might not be revisited for some time. This approach works well in simple environments where there are only a few interfering devices, but can tend to be sub-optimal in complex environments where central intelligence is needed to resolve the problem. There are now a number of companies with interesting solutions to this which gather data from participating nodes and the devices connected to them and seek near-optimal assignment solutions.
We probably will not notice much of this going on. We might be pleasantly surprised that our devices appear to be becoming more intelligent at automatically finding hotspots to connect to. And we might enthuse about the added functionality in our intelligent appliances without giving too much thought as to how they connect to our smart-phones. But this is how it should be – the best solutions are the ones that work quietly and reliably in the background. Turning off the WiFi router in the home, even to have a family conference, will become increasingly unthinkable.
William Webb is an IEEE Fellow, CEO of the Weightless SIG and Director of Webb Search Consulting