Passive RFID is powered by the incoming radio waves that is 1000x stronger than the signal transmission energy from the RFID tag.
There is no statement to the power requirement for passive WIFI from an active WIFI power source. The active WIFI transmitter may require outputting radio waves many times more powerful in order to receive a signal transmission from the passive wifi device.
edit:
For that reason, I'm not that excited about this, and this is likely why it wasn't pursued earlier due to the power requirements of active <-> passive signalling. If it pollutes the EM spectrum with powerful radio waves that are magnitudes more powerful than what we're outputting today, then I hope it gets abandoned. If it's the same power consideration, then it's worth pursuing imo.
Come to think of it, rather than following the usual inverse square law, power should drop off with the fourth power of distance (just like with radar) - there'd be one inverse-square dropoff on the path from active transmitter to transponder, multiplied by a second inverse square loss on the return path. That's got to hurt performance.
The maximum transmitting power is regulated. In the article they state that it can use some kind of crafted wifi packet to be compatible with any existing devices.
Edit: After looking at the pater, it seems that I may have misunderstood the article, it needs a plugged RF carrier tone generator at at fixed frequency.
Imagine coming up with the frequency scheme in an apartment situation; if the building were running the network it would be one thing, but I would expect individual units to foster their own connection.
There is no statement to the power requirement for passive WIFI from an active WIFI power source. The active WIFI transmitter may require outputting radio waves many times more powerful in order to receive a signal transmission from the passive wifi device.
edit: For that reason, I'm not that excited about this, and this is likely why it wasn't pursued earlier due to the power requirements of active <-> passive signalling. If it pollutes the EM spectrum with powerful radio waves that are magnitudes more powerful than what we're outputting today, then I hope it gets abandoned. If it's the same power consideration, then it's worth pursuing imo.