BEGIN:VCALENDAR VERSION:2.0 PRODID:IEEE vTools.Events//EN CALSCALE:GREGORIAN BEGIN:VTIMEZONE TZID:Europe/Stockholm BEGIN:DAYLIGHT DTSTART:20220327T030000 TZOFFSETFROM:+0100 TZOFFSETTO:+0200 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3 TZNAME:CEST END:DAYLIGHT BEGIN:STANDARD DTSTART:20221030T020000 TZOFFSETFROM:+0200 TZOFFSETTO:+0100 RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10 TZNAME:CET END:STANDARD END:VTIMEZONE BEGIN:VEVENT DTSTAMP:20220616T141547Z UID:06EE5122-63E2-4235-8334-3FF338AD8393 DTSTART;TZID=Europe/Stockholm:20220511T101500 DTEND;TZID=Europe/Stockholm:20220511T113000 DESCRIPTION:Nonlinear effects in digital communications: analytical evaluat ion of their effects and how to use them to improve the performance\n\nAbs tract:\n\nIt is widely accepted that nonlinear effects is something that s hould be avoided in digital communications. There are two main reasons for this. The first one is that the theoretical analysis of the impact of a g iven nonlinear device is not simple. The second\, and more important\, is the nonlinear devices can lead to significant spectral widening effects an d/or performance degradation. Since the signals associated to widely emplo yed techniques like OFDM (Orthogonal Frequency Division Multiplexing) and/ or MIMO (Multi-Input\, Multi-Output) schemes can have very large envelope fluctuations and PAPR (Peak-to-Average Power Rate)\, they are prone to non linear distortion effects like the ones associated to quantizers and power amplifiers. For these reasons\, there has been a huge effort in the desig n of quasi-linear amplifiers\, as well as techniques to reduce the PAPR of digital signals.\nIt was recently shown that strong nonlinear distortion effects do not necessarily mean performance degradation. This is due to th e fact that the nonlinear distortion component has some information on the transmitted signals\, which can be employed to improve the performance. I n fact\, the optimum maximum likelihood (ML) performance of nonlinear OFDM schemes can even be better than the performance of the corresponding line ar. However\, the complexity of optimum ML receivers is prohibitively high \, even for a moderate number of subcarriers\, which lead to the developme nt of practical\, sub-optimum receivers able to achieve the optimum perfor mance of nonlinear OFDM.\nIn this talk we start by making an overview on t he common nonlinear characteristics that arise in digital communications\, as well as techniques for studying analytically the impact of nonlinear e ffects on given signals\, with emphasis on the signals associated OFDM tec hniques and MIMO schemes. Then we present some key results on the impact o f nonlinear operations in the spectral occupation and performance. Next\, we study the optimum performance of nonlinear OFDM and MIMO schemes\, show ing the remarkable result that nonlinear techniques can have much better p erformance than the corresponding linear ones. In fact\, a nonlinear devic e at the transmitter can be regarded as a kind of channel coding scheme if it is properly designed. Finally\, we present some practical receivers ab le to harvest these potential nonlinear performance gains.\n\nCo-sponsored by: Local host: Michael Lentmaier\, Lund University\, Sweden\n\nSpeaker(s ): Prof. Rui Dinis\, \n\nRoom: E:2311\, Bldg: E-building\, Lund University \, Dept of Electrical and Information Technology\, Ole Römers väg 3\, Lu nd\, Skane lan\, Sweden\, 223 63\, Virtual: https://events.vtools.ieee.org /m/313148 LOCATION:Room: E:2311\, Bldg: E-building\, Lund University\, Dept of Electr ical and Information Technology\, Ole Römers väg 3\, Lund\, Skane lan\, Sweden\, 223 63\, Virtual: https://events.vtools.ieee.org/m/313148 ORGANIZER:michael.lentmaier@eit.lth.se SEQUENCE:7 SUMMARY:IEEE VT Society Distinguished Lecture (Hybrid) by Prof. Rui Dinis o n Nonlinear Effects in Digital Communications URL;VALUE=URI:https://events.vtools.ieee.org/m/313148 X-ALT-DESC:Description: <br /><p><strong>Nonlinear effects in digital commu nications: analytical evaluation of their effects and how to use them to i mprove the performance</strong></p>\n<p><strong>Abstract</strong>:&nbsp\;< /p>\n<p>It is widely accepted that nonlinear effects is something that sho uld be avoided in digital communications. There are two main reasons for t his. The first one is that the theoretical analysis of the impact of a giv en nonlinear device is not simple. The second\, and more important\, is th e nonlinear devices can lead to significant spectral widening effects and/ or performance degradation. Since the signals associated to widely employe d techniques like OFDM (Orthogonal Frequency Division Multiplexing) and/or MIMO (Multi-Input\, Multi-Output) schemes can have very large envelope fl uctuations and PAPR (Peak-to-Average Power Rate)\, they are prone to nonli near distortion effects like the ones associated to quantizers and power a mplifiers. For these reasons\, there has been a huge effort in the design of quasi-linear amplifiers\, as well as techniques to reduce the PAPR of d igital signals.<br />It was recently shown that strong nonlinear distortio n effects do not necessarily mean performance degradation. This is due to the fact that the nonlinear distortion component has some information on t he transmitted signals\, which can be employed to improve the performance. In fact\, the optimum maximum likelihood (ML) performance of nonlinear OF DM schemes can even be better than the performance of the corresponding li near. However\, the complexity of optimum ML receivers is prohibitively hi gh\, even for a moderate number of subcarriers\, which lead to the develop ment of practical\, sub-optimum receivers able to achieve the optimum perf ormance of nonlinear OFDM.<br />In this talk we start by making an overvie w on the common nonlinear characteristics that arise in digital communicat ions\, as well as techniques for studying analytically the impact of nonli near effects on given signals\, with emphasis on the signals associated OF DM techniques and MIMO schemes. Then we present some key results on the im pact of nonlinear operations in the spectral occupation and performance. N ext\, we study the optimum performance of nonlinear OFDM and MIMO schemes\ , showing the remarkable result that nonlinear techniques can have much be tter performance than the corresponding linear ones. In fact\, a nonlinear device at the transmitter can be regarded as a kind of channel coding sch eme if it is properly designed. Finally\, we present some practical receiv ers able to harvest these potential nonlinear performance gains.</p>\n<p>& nbsp\;</p> END:VEVENT END:VCALENDAR