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A new direction that is being looked at for the Wi-Fi wireless-network ecosystem is the use of “passive Wi-Fi”. This is where Wi-Fi endpoints will not be needing the use of analogue RF amplification circuitry and can simply reflect these wireless signals back to access points or routers.
Traditional active Wi-Fi setups work analogously to a torch (flashlight) that is being used where it is actively putting out the light thanks to its batteries. But passive Wi-Fi works in a similar vein to a mirror that simply reflects the light without using any energy.
The advantage here with passive Wi-Fi is that devices implementing that technology don’t need to draw lots of current for them to operate on the network. This is so appealing towards mobile devices implementing it as a battery-saving measure.
But it also appeals towards how devices related to the smart home or Internet-Of-Things will be designed. This is because these devices can be designed to work for a long time on up to three AA or AAA Duracells or a coin battery, or could use energy-harvesting technologies like solar power or kinetic energy but work with a Wi-Fi network rather than the Bluetooth LE, Zigbee or Z-Wave networks that are optimised for low energy.
Here, it may be feasible to directly connect these devices to your home network and the Internet without the need to use bridge devices to achieve this goal. This is although it can be feasible to integrate Bluetooth LE, Zigbee and/or Z-Wave bridging functionality in to a Wi-Fi-capable router or access point, especially if there is a market expectation to have these devices also serve as “smart-home” or “IoT” hubs.
At the moment, passive Wi-Fi can work between 30-100 feet on a line-of-sight or through walls while passing a bandwidth of up to 11Mbps. The prototypes have been demonstrated with traditional Wi-Fi network equipment including a router and smartphone and this has proven that they can work in a standard Wi-Fi network. But there have been issues raised about requiring routers and access points to broadcast a “wake-up” call for these devices to report their presence and status.
A question that can be asked as this technology is designed is whether it could be feasible to design a Wi-FI front-end to switch between active and passive mode. Here, it could appeal to devices that enter passive mode simply to save energy but “go active” while in use with obvious use cases being mobile devices or Wi-Fi-based handheld controllers.
What it could lead to is that the goal to optimise all of the building-wide wireless-data technologies for low-power use has been nearly completed with the ability to have devices that exploit these technologies able to run for a long time on ordinary batteries.