Very Low Power Wireless Networks

Thursday, August 30, 2012 @ 03:08 PM gHale


When it comes to wireless, power ends up being a huge component into the whole scenario, but that may soon change.

That is because distortion-tolerant communications is now under development for wireless networks that use very little power. The goal is to improve wireless sensors deployed in remote areas where these systems must rely on batteries or energy-harvesting devices for power.

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“Ultra-low power consumption is one of the most formidable challenges faced by the next generation of wireless sensing systems,” said Jingxian Wu, assistant professor of electrical engineering at the University of Arkansas. “These systems will need to operate without interruption for multiple years and with extremely limited battery capacity or limited ability to scavenge energy from other devices. This is why the National Science Foundation was interested in our research.”

In most cases ultra-low power wireless communication devices get their power from batteries or energy harvesting devices such as solar panels. The lower the power consumption, the longer the device can operate without recharging. This is especially important for wireless sensor networks, where the sensors are often in remote areas to monitor items such as water quality, the health of animals and the condition of tunnels, buildings and bridges.

These networks need to operate without interruption over extremely long periods of time without changing batteries. That means it is important to reduce the power consumption so the device can operate for long periods without human intervention.

During data transfer, distortion occurs if the received message is different from the transmitted message. In digital communication systems, the data transmit in the form of zeroes and ones. Due to noise and interference during the transmission process, the receiver might receive a zero when a one transmitted or vice versa. Some critical data or software, such as computer games, requires distortion-free communication. With these systems, any distortion might make the software nonoperational. Other data, such as pictures, music and videos, can tolerate some distortion because human perception might not be sensitive to some of the features.

Conventional research on wireless communication technologies focuses on minimizing distortion through various methods and designs. Conversely, Wu and doctoral student Ning Sun work with distortion-tolerant systems. Rather than limiting or minimizing distortion, their wireless systems allow for controlled distortion, which requires less power than conventional technologies.

“If we accept the fact that distortion is inevitable in practical communication systems, why not directly design a system that is naturally tolerant to distortion?” Wu said. “Allowing distortion instead of minimizing it, our proposed distortion-tolerant communication can operate in rate levels beyond the constraints imposed by Shannon channel capacity.”

Shannon channel capacity is the maximum rate at which distortion-free information can transmit over a communication channel.



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