Tuesday, May 6, 2008

Space is the Current Frontier

In the process of interviewing Bhaskar Rao, the electrical engineer just named named the inaugural holder of the Ericsson Endowed Chair in Wireless Access Networks in the Jacobs School, I learned that in the world of wireless networks, space is the new fronteir.

It's not about going into outerspace with your shiny new PDA. It's about using space as well as time to send information across wireless networks. To enter the wireless world's space dimension, you need to be working with at least two antennae at both the sending and receiving end. Welcome to MIMO: multiple inputs multiple outputs.

When you have mutliple transmitters and recievers, signal processing gets more complicated because you are manipulating space and not just time.

This is super cool because when you're dealing with just one antenna on the transmitter side and one antenna on the receiver side, it is very hard to inrease the data rate. To double the data rate, you have to increase the power of the signal by a factor of 100. That's a lot of work just to double the data rate.

But when you start working with two antennae on both the transmitting and receiving end, the rules change. You can increase data rate without having to raise the power of the signal you are sending or having to increase your bandwidth usage.

The WiMax wireless networks you might have heard about are incorporating MIMO technologies. MIMO is on its way.

For MIMO technologies to function well, the reciever and transmitter have to keep up a regular conversation in which the receiver says, "Hey transmitter! Listen up, this is what I think you said." And based on that information, the transmitter can do a better job of getting its message across the wireless channel to the receiver.

This is called "learning the wireless channel."

Some of Bhaskar Rao's recent work has been in the feedback that the receiver sends the transmitter. You want to be able to send all the relevant information, but nothing more. Also, the wireless channel can change at anytime, so the receiver has to keep sending information to the transmitter.

Who knows when exactly, but pretty soon our laptops and other electronics will have multiple wireless antennae using MIMO to carry data wirelessly at blazing fast speeds. Stay tuned. Space is the current frontier.

You can read more about Bhaskar Rao here.

Here is a link to his laboratory Web page.

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