How smart antennas could boost WiFi performance
A question and answer session with Gonzaga University's Dr. Steven Schennum
By Brad Reed | Network World US | Published: 15:45, 20 October 2010
We've all had the problem of going into a crowded Starbucks and suffering through a substandard Wi-Fi signal, most likely caused by too few access points and too many end users.
But what if Wi-Fi antennas could do a better job of detecting how many devices were in a given room and could push data out to them more rapidly on a one-by-one basis? That's what researchers at Gonzaga University are trying to accomplish by testing "smart antenna" technology in their new research lab that just received a federal research grant worth nearly $1.2 million from the National Science Foundation.
In this interview, we ask Gonzaga electrical engineering associate professor Steve Schennum to outline the basics of smart antenna systems, to describe how they'll improve Wi-Fi performance and to describe how a smart antenna lab would help out small wireless companies.
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What problem is your research into wireless technology trying to address?
The problem is interference. Right now the airspace is full of lots of people trying to communicate over the 2.4GHz band, which is used for Wi-Fi. Our goal is to design a smart antenna that can zero in on a desired signal and reject the others. We're designing software-defined radios that work with the access-point antennas to optimise the signal-to-noise ratio.
So the software will try to optimise the transmission between your computer and the access point wherever it is while also minimising what you're receiving from other computers. The access point would focus itself on one radio at a time. Access points are typically "dumb" in that they radiate some power in all directions at once. So when one computer has a weaker signal or different polarisation, a smart antenna could adjust the polarisation and would form a beam directly to the laptop it wanted to talk to.
Wouldn't this necessarily degrade the quality of signal being sent to other laptops in the area?
The access point would do this very quickly, and actually it would take less time dealing with each radio one at a time than trying to push out data to them all at once. It'll be far less likely that you'll have to retransmit something or have a frame error in your transmission if you do it this way.
So tell me a bit about what the smart antenna lab does
Well, first I just want to clarify that while we're calling it a smart antenna lab, it should really be a smart antenna and radio lab because it's not just antennas. As for the lab itself, part of it is an anechoic chamber that we use for testing radio waves. The chamber is lined with foam that's shaped like cones and that contains carbon fibre in it that absorbs electromagnetic waves. So when you put an antenna in this room, you can rotate the antenna through all of its possible orientations. The receiving antenna on the other end is able to measure the power that it's able to generate.
This isn't a unique setup by any means but it is expensive to set up and a lot of companies don't have this capability. So if they have a product they want to test they can come to our place and do it here. We can even give them an idea of what they might have to do to get their product to meet FCC guidelines.
When do you hope to have the lab up and running?
Hopefully by next spring. We're modifying the room now and finalising decisions about what equipment to buy. This lab will be open to local companies and nearby universities that want to collaborate on research as well, so they can use it to test equipment and they won't have to buy it themselves. We've gotten a lot of support from local industry and we couldn't have done it without them.