Need To Feed Data-Hungry Mobile Devices? Use More Antennas
Researchers at Houston’s Rice University today unveiled a new multi-antenna technology they say could help wireless providers keep pace with the demands of data-hungry smartphones and tablets. Their technology aims to “dramatically increase” network capacity by allowing towers to beam signals simultaneously to more than a dozen customers on the same frequency.
Details about the new technology, dubbed Argos, were presented today at the Association for Computing Machinery’s MobiCom 2012 wireless research conference in Istanbul. Argos is under development by researchers from Rice, Bell Labs and Yale University. A prototype built at Rice this year uses 64 antennas to allow a single wireless base station to communicate directly to 15 users simultaneously via narrowly focused directional beams.
In tests at Rice, Argos reportedly allowed a single base station to track and send highly directional beams to more than a dozen users on the same frequency at the same time. The upshot is that Argos could allow carriers to increase network capacity without acquiring more spectrum, the researchers say.
"The technical term for this is multi-user beamforming," says Argos project co-leader Lin Zhong, associate professor of electrical and computer engineering and of computer science at Rice. "The key is to have many antennas, because the more antennas you have, the more users you can serve."
The theory for multi-user beamforming has been around for quite some time, he adds, but implementing technology has proved “extremely difficult.” Prior to Argos, labs struggled to roll out prototype test beds with a handful of antennas.
"There are all kinds of technical challenges related to synchronization, computational requirements, scaling up and wireless standards," the professor says. "People have really questioned whether this is practical, so it’s significant that we’ve been able to create a prototype that actually demonstrates that this works."
How It Works
Argos presents new techniques that allow the number of antennas on base stations to grow to unprecedented scales. The Argos prototype, which was built by Rice graduate student Clayton Shepard, uses an array of 64 antennas and off-the-shelf hardware, including several dozen open-access test devices called WARP boards that were invented at Rice’s Center for Multimedia Communications.
In tests, Argos was able to beam signals to as many as 15 users on the same frequency simultaneously. For wireless carriers, that performance would translate to more than a six-fold increase in network capacity. According to Zhong, the base-station design can be scaled up to work with hundreds of antennas and several dozen concurrent users, which would result in much higher capacity gains.
"There’s also a big payoff in energy savings," comments Shepard. "The amount of power you need for transmission goes down in proportion to the number of antennas you have. So in Argos’ case, we need only about one-sixty-fourth as much energy to serve those 15 users as you would need with a traditional antenna."
Zhong and Shepard believe Argos is at least five years away from being available on the commercial market. It would require new network hardware and a new generation of smartphones and tablets. It also might also require changes in wireless standards.
"The bandwidth crunch is here, and carriers need options," Zhong notes. "They’re going to pay close attention to any new technologies that may allow them to serve more customers with fewer resources."
Research co-authors include Hang Yu and Narendra Anand at Rice; Li Erran Li and Tom Marzetta at Bell Labs; and Yang Richard Yang of Yale University. The research was supported by the National Science Foundation, Bell Labs, Alcatel-Lucent and the Air Force Office of Sponsored Research.
To learn more about the Argos project, click here