Orthogonal time frequency space (OTFS) modulation is very effective in high Doppler channels by transmitting the information signals in the delay–Doppler domain rather than in the time–frequency domain. Moreover, OTFS provides uniform channel gains across all the transmitted signals thus ensuring the same SNR for all input signals. In this talk, we present the explicit relation between OTFS transmit and receive signals for the delay– Doppler channel with a limited number of paths with delay and Doppler. In particular, we analyze the effect of fractional Doppler on the received signal and show how it causes inter Doppler interference (IDI). We then propose a low-complexity iterative algorithm based on message passing that effectively detects the information signals by canceling IDI. Furthermore, the message passing algorithm complexity scales linearly and can be applied to large-scale OTFS systems. The case of rectangular pulse shaping is also analyzed and it is shown that the performance of ideal bi-orthogonal pulses can still be achieved by a simple phase corrections within the MP algorithm. Simulation results show that the OTFS with the proposed algorithm greatly outperforms the orthogonal frequency division multiplexing (OFDM) schemes in typical wireless channels. This joint work with Raviteja Patchava, Khoa Phan, Yi Hong.
Emanuele Viterbo (M’95–SM’04–F’11) is currently a Professor in the ECSE Department and an Associate Dean in Graduate Research at Monash University, Melbourne, Australia. He received his Ph.D. in 1995 in Electrical Engineering, from the Politecnico di Torino, Torino, Italy. >From 1990 to 1992 he was with the European Patent Office, The Hague, The Netherlands, as a patent examiner in the field of dynamic recording and error-control coding. Between 1995 and 1997 he held a post-doctoral position in the Dipartimento di Elettronica of the Politecnico di Torino. In 1997-98 he was a post-doctoral research fellow in the Information Sciences Research Center of AT&T Research, Florham Park, NJ, USA. From 1998-2005, he worked as Assistant Professor and then Associate Professor, in Dipartimento di Elettronica at Politecnico di Torino. From 2006-2009, he worked in DEIS at University of Calabria, Italy, as a Full Professor. Prof Viterbo is an ISI Highly Cited Researcher (2009). He was an Associate Editor of the IEEE Transactions on Information Theory, the European Transactions on Telecommunications and the Journal of Communications and Networks, and Guest Editor for the IEEE Journal of Selected Topics in Signal Processing: Special Issue on Managing Complexity in Multiuser MIMO Systems. He was awarded a NATO Advanced Fellowship in 1997 from the Italian National Research Council. His main research interests are in lattice codes for the Gaussian and fading channels, algebraic coding theory, algebraic space-time coding, digital terrestrial television broadcasting, digital magnetic recording, and irregular sampling.