"Challenges in Designing Networks Across Large and Fragmented Spectrum"

Vikram Srinivasan, Alcatel-Lucent Bell Labs, India

January 10th (Monday), 11:00am
HFH 4164

There is tremendous interest in the research community in the design of frequency-agile wireless networks. By frequency-agile, we mean that wireless nodes have the ability to tune across large swathes of spectrum. This is motivated by a confluence of emerging technology trends and new spectrum regulations. Recent advances in radiotechnology makes it possible for radios to tune their center frequencies across large swathes of spectrum (100 MHz-8 GHz). Also, these radios cannot only tune their center frequency, but these can also adapt the operating bandwidth. Second, a recent regulation by the FCC allowed the use of unutilized Digital TV Spectrum for unlicensed access. This implies that we now have unlicensed spectrum available from a few 100 MHz (512-698 MHz in DTV whitespaces) all the way up to a few GHz (2.4 GHz and 5.3 GHz ISM bands). A key observation is that different frequency bands have different propagation properties. The lower frequency bands propagate a lot farther than the higher frequency bands. While this implies that lower frequency bands provide better data rates at a fixed distance, it also implies that the lower frequency bands create higher interference to neighboring links. Designing practical networks that operate across such diverse spectrum and manage interference is a challenging problem. We will highlight some of the design challenges and outline some solutions that we have developed to address these challenges.

Towards the end I will give an overview of other research projects, and discuss opportunities available, at Bell Labs India.

About Vikram Srinivasan:

Vikram Srinivasan received his PhD from UCSD in 2003 and ME in ECE from IISc in 1998. He was subsequently an Asst. Professor at the National University of Singapore from 2003-2007. He has been with Alcatel-Lucent Bell Labs in India since 2007. His research interests are broadly in the area of wireless networks. He has published extensively at venues such as ACM Mobicom, IEEE Infocom etc. Along with colleagues, he conceived and led a research project on designing low cost road traffic sensing systems, which has gone on to become the first product out of the research lab in India.

For more information regarding his research, please visit:

Hosted by: Professor Upamanyu Madhow