Limited Feedback

Limited Feedback

Wireless communication systems have improved efficiency in several dimensions in the past decade. One prominent change is the sweeping incorporation of multiple antennas, at both the transmitter and receiver, to achieve higher capacity, better quality, and resilience to interference through new modes of operation. A corresponding advance, resulting from increasing flexibility in the transmitter configuration, is algorithms that adapt the transmit strategy to the dynamic propagation environment. The concept of limited feedback lies at the heart of these two fundamental changes in wireless design. 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.

My research group has made several breakthroughs in limited feedback multiple antenna wireless communication including single user systems, multiple user systems, and multiple cell systems. We have looked at the theory and practice of limited feedback and its applications to narrowband and broadband communication systems. Most recently we have developed limited feedback techniques that exploit the temporal correlation of the channel to further reduce feedback requirements. Our contributions are discussed in more detail in the links on the left.

Select Publications

 

D. J. Love, R. W. Heath, Jr., V. K. N. Lau, D. Gesbert, B. D. Rao, and  M. Andrews, “An Overview of Limited Feedback in Wireless Communication Systems,” IEEE Journal on Sel. Areas in Comm., Special Issue on Exploiting Limited Feedback in Tomorrow’s Wireless Communication Networks, vol. 26, no. 8, pp. 1341-1365, Oct. 2008.

This is our most recent survey article. It includes a comprehensive review of the literature, which is accurate to early 2008 when the manuscript was prepared. The article provides perhaps the most comprehensive summary of limited feedback and explanation of the state-of-the-art.

D. J. Love, R. W. Heath, Jr., W. Santipach,  and  M. L. Honig, “ What is the Value of Limited Feedback for MIMO Channels?,” IEEE Communications Magazine, vol. 42, no. 10, pp. 54-59, Oct. 2003.

This is our earliest overview article on limited feedback communication. It explains the concept of limited feedback as applied to MIMO communication systems including principles such as:

  • Don’t quantize the channel state information directly, quantize what is required by the transmitter.
  • Measure distortion using communication-centric performance measures.
  • Exploit invariances.

This is a great beginning reference coupled with the previous paper.

Sponsors

We have been fortunate to have support for our research on limited feedback from a variety of sponsors including the National Science Foundation (especially NSF-CCF-0514194 and NSF-CCF-0830615), the DARPA ITMANET program W911NF-07-1-0028, not to mention funding in various forms from companies including Motorola, Freescale, Samsung, and Huawei Technologies. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the aforementioned sponsors.

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