New protocol called On-Off Noise Power Communication, on top of the existing Wi-Fi protocol can maintain a signal on as low as 1 bit per second.
" The engineering innovation requires no new hardware to enhance the
signal range for “internet of things” devices, like a door sensor or
motion detector, but can extend the distance these devices can be
installed from a Wi-Fi access point by more than 60 meters, according to
test results."