Akbar Sayeed: New wireless antenna system steers data to reach consumers on the move

Akbar Sayeed peers through an opening in an experimental setup constructed by his team to test the CAPMIMO concept. To his left is a grid of thousands of small filters, normally mounted in the space, which together form a special lens. The filters shift the phases of the electromagnetic waves coming through the lens, focusing beams of the waves in different directions.
Akbar Sayeed peers through an opening in an experimental setup constructed by his team to test the CAPMIMO concept. To his left is a grid of thousands of small filters, normally mounted in the space, which together form a special lens. The filters shift the phases of the electromagnetic waves coming through the lens, focusing beams of the waves in different directions.

Armed with souped-up smart phones, wireless laptops and tablet computers like the iPad, consumers today are sending and receiving images, video and other data-rich files faster than ever before. As mobile traffic continues to explode, however, industry experts are warning that frequent wireless traffic jams could result.

Now, one possible means of easing the congestion is getting a look from industry, thanks to the WARF Accelerator Program. With money from the program and the National Science Foundation, UW–Madison electrical and computer engineering professors Akbar Sayeed and Nader Behdad are building a wireless communication architecture they believe could open information bottlenecks, boost transmission rates and slash the cost of advanced wireless systems.

Dubbed CAP-MIMO, the technology addresses the need for more power and bandwidth efficiency in wireless networks by combining the best of two earlier solutions: large, continuous aperture (CA), or dish, antennas; and multiple antenna systems, known by the acronym MIMO, that send several beams of data simultaneously rather than just one.

What's more, CAP-MIMO employs a special lens for electronically steering data streams in different directions, a capability that's normally achieved with "phased" arrays of thousands of antennas (hence the "P" in CAP-MIMO).

Big dish antennas offer excellent power efficiency, explains Sayeed, but they can't deliver needed transmission rates. Meanwhile, arrays of smaller antennas transmit and receive information at very high rates because of their multiple beams, but their power is no match for a single dish antenna of equal size.

To overcome these drawbacks, CAP MIMO packs four (or more) data streams into the beam emitted by a single CA antenna, rather than using separate antennas to send those four streams.

"We get the multiple data stream advantage of multiple antennas with the big power gain we get from a continuous aperture antenna," says Sayeed.

The result is "a dramatic reduction in complexity," Sayeed says, which could not only cut the cost of high-end military radar and satellite applications, but also could put the technology into consumers' hands. Installed on a rooftop, for example, the lens might direct one antenna beam to a laptop inside the house, while sending another data stream to an HD-TV.

CAP-MIMO might also find use in smart base stations and other applications requiring lightning-fast transmission speeds that have been traditionally achievable only with optical fibers. The team hopes to have a prototype ready for industry representatives to evaluate by summer.

For more information about CAP-MIMO and other information technology projects, contact Emily Bauer, WARF licensing manager, at 608.262.8638 or ebauer@warf.org.