Unless there are specific reasons, no modern mobile device can afford to ignore WiFi, but this comes with a stark truth: WiFi drains batteries. Instead of challenging the limits of current batteries, a group of engineers at the University of Washington created a passive system capable of generating WiFi signals while consuming 10,000 times less energy than traditional WiFi.
Name one of the most important recommendations for saving energy on a mobile device. The first might be reducing screen brightness, but immediately the suggestion to turn off WiFi when not in use appears. Most optimizations in WiFi technology have focused on the digital "baseband" (since it has kept pace with Moore's Law), leaving the analog RF module untouched. This marks a huge difference in power consumption between the two components, and it compromises the development of future concepts, like the famous "Internet of Things" that is notably absent. At the University of Washington they believe it is necessary to redesign WiFi as we know it to reduce its energy dependence, which brings us to Passive WiFi
Separating Digital and Analog
Basically, what they propose with their prototypes is separating the digital from the analog. A central device manages all RF, while the rest of the passive units keep only the digital baseband. At the same time, the passive units "reflect" the signal selectively (the term is "backscattering") and generate WiFi packets that can be decoded by existing devices. With this process, they consume about 16 microwatts, 10,000 times less than a normal WiFi. If we compare it with other transmission methods like Bluetooth Low Energy or the Zigbee specification, the consumption is a thousand times less
The fact that these passive modules can communicate with any existing WiFi device is very positive, and as if that weren't enough, tests indicate that the maximum range is about 30 meters. Now, if there is a limitation to consider in passive WiFi, it is performance. Its speed puts it on par with WiFi "b", or 11 megabits per second. This might not be enough for more demanding cases (4K streaming, for example), but with such a significant and dramatic reduction in energy consumption, I think it is something tolerable.
