Category Archives: Lectures

On behalf of the IEEE joint VT/COM/IT Sweden Chapter Board, We are delighted to invite you to an IEEE Technical Seminar by Prof. Krishna Narayanan, Texas A&M University, US.

Time: Mon June 11, 2018, at 15:15-16:30
Location: Room E:2517, floor 2, E building, John Erikssons väg 4, Lund University, 223 63 Lund (Link to google maps)
Local host: Michael Lentmaier, michael.lentmaier@eit.lth.se

Title: Coding and Compressed sensing Inspired Massive Uncoordinated Multiple Access for Next-Generation Wireless Systems

Abstract:
Currently, there is significant interest in the design of multiple access schemes for large-scale wireless networks where coordination among users is difficult to acquire and maintain. This interest appears to be fueled by applications such as machine-to-machine communications, vehicular networks, Internet of Things, etc, which are all important components of 5G wireless. We are primarily interested in answering two questions in this talk – (i) how to design good random access protocols for such large-scale networks and (ii) What is the penalty due to the lack of coordination among users?
Traditional random access protocols such as slotted ALOHA suffer from a severe loss in throughput due to the lack of coordination (the throughput efficiency of slotted ALOHA is 37%). This inefficiency is primarily because collided packets are discarded in traditional slotted ALOHA. In this talk, we will show how to overcome this deficiency using ideas from coding theory and signal processing. We will first consider the collision channel and show that coded slotted ALOHA with iterative collision resolution is asymptotically optimal for the collision channel. For the uncoordinated Gaussian multiple access channel, we will show how to design computationally efficient uncoordinated multiple access schemes using ideas from coding theory (message passing, codes on graphs) and compressed sensing. These schemes provide the best performance among pragmatic multiple access schemes that are currently known for the Gaussian multiple access channel.

For any further questions, please contact the local host.

Biography:
Krishna Narayanan received the Ph.D. degree in Electrical Engineering from Georgia Institute of Technology in 1998. Since then, he has been with the Department of Electrical and Computer Engineering at Texas A&M University, where he is currently the Eric D. Rubin professor. His research interests are in coding theory, information theory, and signal processing with applications to wireless networks, data storage and data science. His current research interests are in the design of uncoordinated multiple access schemes and in exploring connections between sparse signal recovery and coding theory. He was the recipient of the NSF career award in 2001. He also received the 2006 best paper award from the IEEE technical committee for signal processing for data storage for his work on soft decision decoding of Reed Solomon codes. He currently serves as an Associate editor for the IT Transactions and also serves on the board of governors of the IT society. He is a fellow of the IEEE and he has won several awards within Texas A&M university including the 2018 university-level teaching award.

On behalf of the IEEE joint VT/COM/IT Sweden Chapter Board, We are delighted to invite you to an IEEE Technical Seminar by Prof. Christoph Mecklenbräuker, Vienna University of Technology, Vienna, Austria.

Time: Wed June 13, 2018, at 15:00-16:00
Location: Room EB, floor 4, EDIT building, Chalmers University of Technology, Hörsalsvägen 11, Gothenburg (Link to google maps)
Local host: Fredrik Brännström, fredrik.brannstrom@chalmers.se

Title: Channel Characterisation for Dependable Vehicular Connectivity at 6 and 60 GHz

Abstract:
Challenges for Cooperative Intelligent Transport Systems (C-ITS) are posed by the nonstationary time–frequency-selective fading processes in vehicular channels. Fortunately, the nonstationary vehicular fading may be characterized by assuming local stationarity for a finite region in the time-frequency plane. For such region, the wide-sense stationarity and uncorrelated scattering assumptions hold approximately. Thus, it makes sense to characterize the channel by a local scattering function (LSF). Estimates for the LSF from measurements collected in the DRIVEWAY’09 campaign at 5-6 GHz are discussed focusing on ITS scenarios. Subsequently, the time–frequency-varying power delay profile (PDP) and the time–frequency-varying Doppler power spectral density (DSD) are discussed. Based on these, the time–frequency-varying delay and Doppler spreads are evaluated. High delay spreads are observed in situations with rich scattering, whereas high Doppler spreads characterize drive-by scenarios. Early LSF results for 59.75–60.25 GHz millimetre wave V2V channel measurements in an urban street (Vienna, Austria) are presented. Measurements have been acquired in September 2017 with a time-domain channel sounder. Estimates for delay and Doppler profiles are evaluated from the LSF for overtaking vehicles. Passenger cars are associated with a single Doppler trajectory, whereas lorries show up in the LSF with multiple Doppler trajectories.

For any further questions, please contact the local host.

Biography:
Christoph Mecklenbräuker received the Dipl-Ing. degree in Electrical Engineering from Vienna University of Technology in 1992 and the Dr.-Ing. degree from Ruhr-University of Bochum in 1998, respectively. His doctoral thesis was awarded with the Gert Massenberg Prize. From 1997- 2000, he worked for the Mobile Networks Radio department of Siemens AG Austria participating in ACTS 90 FRAMES. He was a delegate to the Third Generation Partnership Project (3GPP) and engaged in the standardization of UMTS. Since June 2000, he was a senior researcher at the Telecommunications Research Center Vienna (ftw.) in the field of mobile communications, key researcher since November 2002, and proxy since July 2003. Between 2006 and 2009, he coordinated the FP6 project “Multiple-Access Space-Time Coding Testbed” (MASCOT) on behalf of ftw. He was active in COST Action 2100 Pervasive Mobile and Ambient Wireless Communications and COST Action IC1004 Cooperative Radio Communications for Green Smart Environments. In 2006, he joined the Institute of Communications and Radio Frequency Engineering at Vienna University of Technology as a full professor. Since July 2009, he leads the Christian Doppler Laboratory for Wireless Technologies for Sustainable Mobility. His current research interests include radio interfaces for future vehicle-to-vehicle and vehicle-to- infrastructure communications, RFID-based wireless tags and sensors, ultra-wideband radio (UWB) and MIMO-OFDM based transceivers (4G LTE and beyond). Christoph Mecklenbräuker is a member of the IEEE, the Antennas and Propagation Society, the Vehicular Technology society, the Signal Processing society, and the Intelligent Transportaton Society. He is senior editor of the IEEE Transactions on Intelligent Transportation Systems. He is the councilor of the IEEE Student Branch Wien. Christoph Mecklenbräuker is a member of EURASIP. He is associate editor of the EURASIP Journal of Advances in Signal Processing.