Improving the efficiency of wireless access

An increase in wireless application demand has put the radio frequency spectrums used for wireless communication in a crunch for space, often resulting in slower response times. To combat this issue, CSL researchers Jin Zhou and Haitham Hassanieh, along with ECE faculty member Songbin Gong, are trying to improve the efficacy of current spectrums in their recently funded project, “Energy-efficient chip scale sensing of crowded wide spectrum.”

“The problem is our spectrum has become more and more crowded; we have a spectrum crunch,” said Zhou, assistant professor of electrical and computer engineering. “The spectrum is in extremely high demand and very expensive. Improvements to use it

efficiently will be important.”

Zhou compares the spectrum problem to the problem of filling a parking lot. Current spectrums operate from a single paradigm wherein every wireless user has a certain spot, like a parking lot with assigned spaces. Even when the user (or assigned car) is not present, the space is still unavailable for others To enhance spectrum efficiency, wireless researchers and spectrum regulators, such as the FCC, would like to make it so the spectrum can operate on a dynamic paradigm, wherein everyone has shared access to the bandwidth (or parking spaces) as needed.

One major challenge of shared spectrum access is the extensive amount of data and the energy required to monitor a crowded wide spectrum in real time. To return to the parking lot analogy, in order for current spectrum monitoring approaches to reveal how many parking spaces are vacant, it needs to see the entirety of every parking space, even those currently occupied, resulting in a lot of wasted energy and data. An efficient sensing technology, such as the kind that Zhou, Hassanieh, and Gong are envisioning, would only need to see a small portion of each parking space to determine whether or not the space was occupied -- requiring less data and energy.

“You don’t have to look at the entire spot to tell whether there is a car parked or not. This is the same way we’ll solve the problem with spectrum sensing. You just need to see a portion,” Hassanieh said. “The information collected is sparse. You can’t see the majority of the data, but you see partial things that provide sufficient information.”

“What allows us to monitor a small part of each spectrum channel (or parking space) is a microelectromechanical device that could be closely integrated with a radio microchip,” Gong added. “We are the first to use this type of devices for spectrum sensing applications.”

The goal of the new project is to develop a tool that will allow the spectrums to be used in this more efficient way, which would lead to improved access for all users. The team hopes to test their tool on the University’s campus and then use the results to influence FCC policy on shared access.

“There could be more devices that have low-cost and energy-efficient wireless access, opening up new opportunities,” Zhou said. “Once the FCC thinks there are enough results to adopt sharing-based policy, it can be used in people’s everyday lives.”

The project was funded by the National Science Foundation for three years for $675,000.