Wireless Networking


Bhaskar Rao: Conquering Space and Time With MIMO

Bhaskar Rao is known for his discoveries in the realm of space exploration. However, he’s never ventured beyond the atmosphere of Mother Earth. His space-related technology expertise lies in innovative advances in the world of signal processing. His explorations resulted in the emergence of MIMO, or multiple input multiple output.

An electrical engineer from the University of California at San Diego’s Jacobs School of Engineering, Rao’s discoveries are contributing to advances in wireless communications networks. His work will help to develop ways for high-quality video and other high-data-rate content to flow across wireless channels without increased power consumption or bandwidth usage. So far, this technology is only effective in areas where wireless channel conditions are suitable.

Rao’s accomplishments in this cutting-edge area of digital signal processing contributed to his being named the inaugural holder of the Ericsson Endowed Chair in Wireless Access Networks in the Jacobs School. He uses this leadership role as part of his ongoing support of the UCSD division of the California Institute for Telecommunications and Information Technology (Calit2). The endowment is provided by electronics manufacturer Ericsson through its corporate commitment to the UCSD division of Calit2.

A Long List of Accomplishments

Rao earned his doctorate from the University of Southern California in 1983 and joined the UCSD faculty that same year. Throughout his 25-year tenure there, Rao has spent time with Qualcomm, Microsoft Research, AT&T Bell Labs and Stanford University in various research and consulting capacities.

His work in electrical engineering is reflected in more than 200 journal and conference publications involving signal processing, estimation theory, speech coding, multiple-antenna transmission and space-time coding. One of his latest accomplishments was sharing the 2008 Stephen O. Rice Prize Paper Award in the field of communications systems. This award was given jointly to Rao, fellow electrical engineering professor Rene Cruz and Cruz’s doctoral student, Bongyong Song.

“Professor Rao is one of the people I recommend my students to model themselves after if they are considering an academic career. He is creative, hard-working and has very high standards,” professor Larry Larson, chair of the Electrical and Computer Engineering Department at UC San Diego’s Jacobs School of Engineering, told TechNewsWorld. “He takes his role as a teacher very seriously. He is invariably gracious and patient to students, and he makes sure his students get the credit for their excellent research. He is a real pleasure to work with — collegial, and always willing to lend a hand on any tough problem here at UCSD.”

Significant Work

Rao’s work in MIMO techniques are significant, said Larson. MIMO techniques are key for next-generation wireless networks. They will enable seamless and video-oriented wireless communications with low-cost, consumer-oriented devices.

“There are so many hurdles, it is hard to know where to start describing what lies ahead for him. What is the effect of interference on these algorithms? How do they work in diverse networks? How practical are they to implement? These are all tough, unresolved problems,” Larson noted.

TechNewsWorld discussed with Rao the implications of his research and his views on future wireless developments.

TechNewsWorld: What makes MIMO advancements so significant to today’s communication technology?

Bhaskar Rao:

The conventional technology is limited to having a single antenna. Now it is possible to have multiple antennae in both transmitter and receiver to add more power at the same cost.

TNW: In layman’s terms, why is this development so important?


The real excitement is that this opens up new possibilities for signal-to-noise ratio. It takes more power to double this rate. The capacity scales linearly with the same power and bandwidth. This is the real benefit. It is all in the hardware at no new cost.

TNW: How long will consumers have to wait for this MIMO technology to be available?


It is already being used as the new WiMax standard. This wireless technology is in new products. You can see the MIMO label on the cartons of products that use it.

TNW: What led you to this particular field of research? Is it an area that nobody previously studied?


I am a latecomer to this research. Bell Labs had worked on what it called a “Blast System” in 1994 and 1995. After that, more people joined in researching other solutions.

[Editor’s Note: According to the Bell Labs’ Web site, BLAST is a bandwidth-efficient approach to wireless communication that takes advantage of the spatial dimension by transmitting and detecting a number of independent co-channel data streams using multiple, essentially co-located, antennas. In laboratory tests, Bell Labs researchers demonstrated wireless spectral efficiencies that ranged from 20 to 40 bps/Hz (bits per second per hertz). By comparison, the efficiencies achieved using traditional wireless modulation techniques range from around 1 to 5 bps/Hz (mobile cellular) to around 10 to 12 bps/Hz (point-to-point fixed microwave systems).]

TNW: What hurdles had to be overcome to get to where you are now with MIMO technology?


This new development is an engineering dream come true. We were working on this for 10 years. We were working on this with student assistance and fellow faculty at our Center for Wireless Communications.

TNW: Are you, as a principal researcher of MIMO, involved in any patents on this new technology?


In academia, there are no patents. A lot of university talent went into working on this.

TNW: What factors contributed to the success of your research group in developing MIMO technology?


We have a strategic location for both funding and publicity. With this good visibility, we were thrust into the forefront and into success with the first phase of development.

TNW: What happens next? Are you considering another horizon to research?


To the contrary. We are still working on MIMO. This working technology is now in its deployment phase, so we can learn about problems that need solutions as we move forward with the technology.

TNW: What do you see as the potential impact of MIMO technology on wireless communications?


I hope to see our footprint get smaller. This technology can be deployed in all aspects of communication. Until MIMO, we were limited to samplings in space. Now we have samplings in both space and time. We can deploy it in any context as a result. It opens up the question, “What can you do with the environment?”

TNW: How significant is this conquering of the spatial dimension for future communications technology?


Space is the new dimension in communication. Previously, communication was based on frequency. We assigned separate frequencies to separate uses. Now we can use the same frequencies with separation created by different space.

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