EE Systems Seminar

ABSTRACT Frame asynchronous coded slotted ALOHA (FA-CSA) is an uncoordinated multiple access scheme, but in some sense equivalent to spatially coupled low-density parity-check (SC-LDPC) codes. We analyze the performance of FA-CSA in terms of packet loss rate and delay, where we derive tight approximations of the error floor (EF) for the finite frame length regime. We show that, in general, FA-CSA provides better performance in both the EF and waterfall regions as compared to its frame synchronous version. We also analyze the finite-length performance in the waterfall region of SC-LDPC codes under window decoding over the binary erasure channel. In particular, we propose a refinement of the scaling law proposed by Olmos and Urbanke for both the frame and bit error rate of terminated SC-LDPC ensembles under full belief propagation decoding, and also extend the analysis under the more practical sliding window decoding.

BIO Fredrik Brännström is Professor and Head of the Communication Systems Group, Department of Electrical Engineering, Chalmers University of Technology, Gothenburg, Sweden. He received the M.Sc. degree from Luleå University of Technology, Luleå, Sweden, and the Ph.D. degree in Communication Theory from the Department of Computer Engineering, Chalmers University of Technology, Gothenburg, Sweden. From 2006 to 2010, he was a Principal Design Engineer with Quantenna Communications, Inc., Fremont, CA. He was a recipient of the 2013 IEEE Communication Theory Workshop Best Poster Award. In 2014, he received the Department of Signals and Systems Best Teacher Award. Together with his students he has co-authored the papers that received the 2016 and 2017 Best Student Conference Paper and the 2018 Best Student Journal Paper, all awarded by the IEEE Sweden Joint VT-COM-IT Chapter. His current research interests include algorithms, resource allocation, synchronization, antenna concepts, and protocol design for vehicular communication systems, as well as different applications of coding.