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Wednesday, October 23, 2019

Protocol boosts WiFI range for smart home IoT devices

By Nick Flaherty www.flaherty.co.uk

A group of researchers in the US has created a protocol that significantly extends the distance a Wi-Fi-enabled device can send and receive signals as noise and could be implemented as a software upgrade.

Test results for the On-Off Noise Power Communication (ONPC) protocol show a boost of over 60m, which could also be used to reduce power consumption and extend battery li.

"That's the really cool thing about this technology: it's all done in software," said Phil Lundrigan, assistant professor of computer engineering at led by a Brigham Young University (BYU). "In theory, we could install this on almost any Wi-Fi-enabled device with a simple software update."

ONPC is programmed right on top of the existing Wi-Fi protocol using the same hardware. While Wi-Fi requires speeds of at least one megabit per second (1 Mbps) to maintain a signal, the "ONPC" protocol Lundrigan and his co-authors created can maintain a signal on as low as 1 bit per second -- one millionth of the data speed required by Wi-Fi.

To do so, Lundrigan, Neal Patwari of Washington University (in St. Louis) and Sneha Kasera of the University of Utah adjusted the transmitter in a Wi-Fi-enabled device to send wireless noise in addition to data. They programmed into the Wi-Fi sensor a series of 1s and 0s, essentially turning the signal on and off in a specific pattern. The Wi-Fi router was able to distinguish this pattern from the surrounding wireless noise (from computers, televisions and cell phones) and therefore know that the sensor was still transmitting something, even if the data wasn't being received.

"If the access point (router) hears this code, it says, 'OK, I know the sensor is still alive and trying to reach me, it's just out of range,'" said Patwari. "It's basically sending one bit of information that says it's alive."

But according to Lundrigran, one bit of information is sufficient for many Wi-Fi enabled devices that simply need an on/off message, such as a garage door sensor, an air quality monitor or even a sprinkler system. During the research, the team successfully implemented their ONPC protocol, along with an application to manage the protocol ("Stayin' Alive"), ultimately extending the range of an off-the-shelf device 67 meters beyond the range of standard Wi-Fi.

The researchers made clear to point out that their ONPC protocol is not meant to replace Wi-Fi or even long-range wireless protocols like LoRa, but is meant to supplement Wi-Fi. Specifically, only when Stayin' Alive detects that the Wi-Fi device has lost its connection, it starts transmitting data using ONPC.

The protocol can also be used with LoRa sub-GHz links. "We can send and receive data regardless of what Wi-Fi is doing; all we need is the ability to transmit energy and then receive noise measurements," Lundrigan said. "We could apply this to cellular or Bluetooth as well," he said.

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