Robert W. Heath, Jr. Delivers Plenary at the Fourth International Workshop on Computational Advances in Multi-Sensor Adaptive Processing

Sunday, January 22, 2012

On December 15, 2011, Professor Heath delivered a Plenary talk at the Fourth International Workshop on Computational Advances in Multi-Sensor Adaptive Processing. The CAMSAP workshop is dedicated to theoretical topics such as convex optimization and relaxation, computational linear algebra, distributed algorithms, and sparse signal processing as well as their applications to array processing, communication systems, sensor networks, biomedicine, computational imaging, and emerging topics. Prof. Heath's talk was entitled The Limited Feedback Revolution in Wireless Communication. Limited feedback communication has been a substantial component of Prof. Heath's research for the past ten years. Limited feedback is a methodology for obtaining and exploiting propagation channel state information at the transmitter. It uses a finite rate feedback control channel to convey quantized observations of the channel from the receiver to the transmitter. Limited feedback allows the transmitter to adjust how antennas are configured and change other parameters like the transmission rate to maximize performance. Limited feedback has been developed to improve performance in MIMO (multiple input multiple output) communication links, multiuser MIMO links, and network MIMO systems. The concept of limited feedback is part of several commercial wireless systems including 3GPP LTE, WiMax, and IEEE 802.11n. In the plenary, Prof. Heath reviewed several breakthroughs in limited feedback multiple antenna wireless communication. In particular, he explained the connection between limited feedback and quantization on the Grassmann manifold. Then he described a new application of limited feedback to interference channels. The idea is to leverage temporal correlations in the channel through a new predictive coding framework that reduces feedback rates and/or increases effective resolution. The application of this new framework specifically for high resolution limited feedback in interference channels was discussed. A main conclusion was that limited feedback could be used to implement interference alignment in slowly varying channels, making it a viable transmission technique for future cellular and ad hoc networks. Prof. Heath is available to reprise his plenary through the IEEE Vehicular Technology Society Distinguished Lecturer program.