The MIMO-ARQ channel: optimal diversity-multiplexing-delay tradeoff

SPEAKER: Dr. Giuseppe Caire, Dept of Mobile Communications, Institute EurecomABSTRACT: In this talk, we explore the fundamental performance tradeoff of the delay-limited Multi-Input-Multi-Output (MIMO) Automatic Retransmission reQuest (ARQ) channel. In particular, we extend the diversity-multiplexing tradeoff defined by Zheng and Tse in standard delay-limited MIMO channels with coherent detection to the hybrid ARQ scenario. We establish the three-dimensional tradeoff between reliability (i.e. diversity), throughput (i.e., multiplexing gain), and delay (i.e., maximum retransmission delay). This tradeoff quantifies the ARQ diversity gain obtained by leveraging the retransmission delay to enhance the reliability for a given multiplexing gain. Interestingly, ARQ diversity appears even in long-term static channels where all the retransmissions take place in the same channel state. Then, we show how power control, if possible, can be used to further increase the diversity advantage, for a given multiplexing gain and maximum retransmission delay. Our analysis reveals some important insights on the benefits of ARQ in slow fading MIMO channels. In particular, we show that: 1) allowing for a sufficiently large retransmission delay results in an almost flat diversity-multiplexing tradeoff, and hence, renders operating at high multiplexing gain more advantageous; 2) MIMO ARQ channels quickly approach the no-outage limit when power control is employed. Finally, we complement our information theoretic analysis with an incremental redundancy LAttice Space-Time (LAST) coding scheme which is shown, through a random coding argument, to achieve the optimal tradeoff(s) when used with an MMSE-Lattice decoder. Throughout the paper, our theoretical claims are validated by numerical results.BIO: Giuseppe Caire was born in Torino, Italy, in 1965. He received the B.Sc. in Electrical Engineering from Politecnico di Torino (Italy), in 1990, the M.Sc. in Electrical Engineering from Princeton University in 1992 and the Ph.D. from Politecnico di Torino in 1994. He was a recipient of the AEI G.Someda Scholarship in 1991, has been with the European Space Agency (ESTEC, Noordwijk, The Netherlands) from May 1994 to February 1995, was a recipient of the COTRAO Scholarship in 1996 and of a CNR Scholarship in 1997. He has been visiting Princeton University in summer 1997 and Sydney University in summer 2000.He has been Assistant Professor in Telecommunications at the Politecnico di Torino, Associate Professor at the University of Parma, Italy, and presently he is Professor with the Department of Mobile Communications of the Institute Eurecom, Sophia-Antipolis, France.He served as Associate Editor for the IEEE Transactions on Communications in 1998-2001 and as Associate Editor for the IEEE Transactions on Information Theory in 2001-2003. He received the Jack Neubauer Best System Paper Award from the IEEE Vehicular Technology Society in 2003, and the Joint IT/Comsoc Best Paper Award in 2004.His current interests are in the field of communications theory, information theory and coding theory with particular focus on wireless applications.Host: Dr. P. Vijay Kumar, x.04668, vijayk@usc.edu

Location: Hedco Neurosciences Building (HNB) - 100

Audiences: Everyone Is Invited

Contact: Mayumi Thrasher