Christian Hofbauer

Christian Hofbauer
SAL Silicon Austria Labs · RF Systems/Wireless Communications

Dr. techn.

About

33
Publications
3,940
Reads
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411
Citations
Citations since 2016
12 Research Items
236 Citations
201620172018201920202021202201020304050
201620172018201920202021202201020304050
201620172018201920202021202201020304050
201620172018201920202021202201020304050
Additional affiliations
August 2019 - present
SAL Silicon Austria Labs
Position
  • Senior Researcher
September 2015 - present
Linz Center of Mechatronics GmbH
Position
  • Senior Researcher
September 2013 - September 2015
Johannes Kepler University Linz
Position
  • Research Assistant
Education
September 2007 - June 2016
Alpen-Adria-Universität Klagenfurt
Field of study
  • Information Technology
October 2002 - June 2006
Fachhochschule Oberösterreich
Field of study
  • Hardware Software Systems Engineering

Publications

Publications (33)
Article
Full-text available
Many radar applications require a high range resolution, entailing the necessity for a large signal bandwidth. When employing an orthogonal frequency-division multiplexing (OFDM) radar system in its standard implementation, the radar system must operate at a high sampling frequency to ensure covering the entire signal bandwidth, thus imposing signi...
Article
Full-text available
An orthogonal frequency-division multiplexing (OFDM) waveform enables simultaneous radar sensing and communications. In the multiple-input multiple-output (MIMO) case with several transmit (Tx) antennas, multiplexing the transmit signals is usually implemented using equidistant subcarrier interleaving (ESI), thus allowing the separation of the tran...
Article
Unique word-orthogonal frequency division mul-tiplexing (UW-OFDM) is known to provide various performance benefits over conventional OFDM using cyclic prefixes (CP). Most important, UW-OFDM features excellent spectral sidelobe suppression properties and an outstanding bit error ratio performance. Current research has mainly focused on principle per...
Conference Paper
Full-text available
Unique word-orthogonal frequency division multiplexing (UW-OFDM) provides several performance benefits over conventional cyclic prefix (CP) based OFDM, such as excellent spectral sidelobe suppression properties and an outstanding bit error ratio performance. Aside from idealized assumptions, each communication system faces challenges in conducting...
Preprint
Unique word-orthogonal frequency division multiplexing (UW-OFDM) is known to provide various performance benefits over conventional OFDM using cyclic prefixes (CP). Most important, UW-OFDM features excellent spectral sidelobe suppression properties and an outstanding bit error ratio performance. Current research has mainly focused on principle perf...
Article
Full-text available
Biased estimators can outperform unbiased ones in terms of the mean square error (MSE). The best linear unbiased estimator (BLUE) fulfills the so called global conditional unbiased constraint when treated in the Bayesian framework. Recently, the component-wise conditionally unbiased linear minimum mean square error (CWCU LMMSE) estimator has been i...
Conference Paper
In soft decoding, log-likelihood ratios (LLRs) are calculated from estimated data symbols. Data symbols from proper constellation diagrams such as QPSK are often estimated using the linear minimum mean square error (LMMSE) estimator. We prove that the recently introduced component-wise conditionally unbiased (CWCU) LMMSE estimator results in the ve...
Article
Full-text available
In soft decoding of data bits, the log-likelihood ratios are evaluated from the estimated data symbols. For proper constellation diagrams such as QPSK or 16-QAM, these data symbols are often estimated using the linear minimum mean square error (LMMSE) estimator. The LMMSE estimator only fulfills the weak Bayesian unbiasedness constraint. Recently,...
Conference Paper
Full-text available
In this paper we consider a unique word OFDM (UW-OFDM) system with iterative detection, for which we explore two soft-input soft-output (SISO) detection algorithms: A LMMSE detector and a detector based on the generalized approximate message passing (GAMP) algorithm. For the GAMP based detector we propose additional simplifications suitable for UW-...
Article
Full-text available
Unique word-orthogonal frequency division multiplexing (UW-OFDM) is a novel signaling concept where the guard interval is implemented as a deterministic sequence, the so-called unique word. The UW is generated by introducing a certain level of redundancy in the frequency domain. Different data estimation strategies and the favourable bit error rati...
Conference Paper
Full-text available
Unique word - orthogonal frequency division multiplexing (UW-OFDM) is known to feature an excellent bit error ratio performance when compared to conventional OFDM using cyclic prefixes (CP). In recent papers linear and non-linear UW-OFDM receivers have been investigated and compared for proper data vectors consisting of QPSK and 16-QAM symbols. In...
Conference Paper
Unique word – orthogonal frequency division multiplexing (UW-OFDM) is a novel transmit signal structure for OFDM where the usual cyclic prefixes (CPs) are replaced by deterministic sequences, the so-called UWs. Since unique words represent known sequences, they can advantageously be used for synchronization and estimation tasks, but also for improv...
Article
Full-text available
Unique word orthogonal frequency division multiplexing (UW-OFDM) inherently introduces a complex number Reed Solomon (RS) code. Originally, the code generator matrix of systematic coded UW-OFDM had been designed rather intuitively by minimizing the mean redundant energy. In this work we justify this approach by applying a cost function that incorpo...
Article
Full-text available
In this paper, we expand our recently introduced concept of unique word orthogonal frequency division multiplexing (UW-OFDM). In UW-OFDM the cyclic prefixes (CPs) are replaced by deterministic sequences, the so-called unique words (UWs). The UWs are generated by appropriately loading a set of redundant subcarriers. By that a systematic complex numb...
Article
Full-text available
Unique word—orthogonal frequency division multiplexing (UW-OFDM) is a novel OFDM signaling concept, where the guard interval is built of a deterministic sequence—the so-called unique word—instead of the conventional random cyclic prefix. In contrast to previous attempts with deterministic sequences in the guard interval the addressed UW-OFDM signal...
Conference Paper
Full-text available
UW-OFDM (unique word – orthogonal frequency division multiplexing) is a novel OFDMsignaling concept, where the guard interval is built of a deterministic sequence – the so-called unique word – instead of the conventional random cyclic prefix. In contrast to previous attempts with deterministic sequences in the guard interval, the addressed UW-OFDM...
Conference Paper
Full-text available
Unique word - orthogonal frequency division multiplexing (UW-OFDM) is a novel OFDM concept that uses deterministic sequences, which we call unique words, as guard intervals instead of the conventional cyclic prefixes. Since unique words represent known sequences, they can advantageously be used for sychronization, channel estimation, but also for i...
Conference Paper
Full-text available
The concept of using unique word (UW) prefixes instead of cyclic prefixes (CPs) is already well investigated for single carrier systems with frequency domain equalization (SC/FDE). In OFDM (orthogonal frequency division multiplexing), where the data symbols are specified in frequency domain, the introduction of UWs - which are specified in time dom...
Conference Paper
Full-text available
In this paper, we propose a novel transmit signal structure for OFDM (orthogonal frequency division multiplexing). Instead of the conventional cyclic prefix (CP), we use a deterministic sequence, which we call unique word (UW), as guard interval. We show how unique words, which are already well investigated for single carrier systems with frequency...
Conference Paper
Full-text available
Recently we presented a novel OFDM (orthogonal frequency division multiplexing) signaling concept, where the cyclic prefixes (CPs) are replaced by deterministic sequences which we call unique words (UWs). The UWs are generated by appropriately loading so-called redundant subcarriers. By that a complex number Reed Solomon (RS) code construction is i...
Conference Paper
Full-text available
In this paper we propose a novel transmit signal structure and an adjusted and optimized receiver for OFDM (orthogonal frequency division multiplexing). Instead of the conventional cyclic prefix (CP) we use a deterministic sequence, which we call unique word (UW), as guard interval. We show how unique words, which are already well investigated for...
Article
Full-text available
In this paper we propose a novel transmit signal structure and an adjusted and optimized receiver for OFDM (orthogonal frequency division multiplexing). Instead of the conventional cyclic prefix we use a deterministic sequence, which we call unique word (UW), as guard interval. We show how unique words, which are already well investigated for singl...
Conference Paper
Full-text available
Spatial Multiplexing (SM) is an effective means for enhancing the transmission data rate in Multiple-Input Multiple- Output (MIMO) systems, particularly when used in combination with precoding. Precoding based on the knowledge of the slow-varying statistics of the channel exploits this information at the transmitter to combat the effect of fading i...
Conference Paper
Spatial Multiplexing (SM) is an effective means for enhancing the transmission data rate in Multiple-Input Multiple-Output (MIMO) systems, particularly when used in combination with precoding techniques. However, it is not always obvious to connect the performance of such a system to its number of data streams and antennas. In this paper, the diver...
Article
Full-text available
The concept of cooperative relaying promises gains in robustness and energy efficiency in wireless networks. This survey gives an introduction and overview of promising methods that can be used for cooperative relaying: relay selection protocols, cooperative channel and network coding, and physical layer aspects such as cooperative modulation. The...
Article
Full-text available
The concept of cooperative relaying promises gains in robustness and energy efficiency in wireless networks. This survey gives an introduction and overview of promising methods that can be used for cooperative relaying: relay selection protocols, cooperative channel and network coding, and physical layer aspects such as cooperative modulation. The...
Conference Paper
Spatial Multiplexing (SM) is an e�ective means for enhancing the transmis- sion data rate in Multiple-Input Multiple-Output (MIMO) systems, particularly when used in combination with precoding. Precoding based on the knowledge of the slow-varying statistics of the channel exploits this information at the trans- mitter to combat the e�ect of fading...

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Projects (2)
Project
https://silicon-austria-labs.com/en/sal-doctoral-college/ The Silicon Austria Labs – Doctoral College (SAL-DC) is a novel doctoral training programme for researchers focusing on the field of electronic based systems (EBS). SAL coop­er­ates with industry, acad­emic and scien­tific part­ners on a regional, national and inter­na­tional level with the aim to build an excel­lent re­search network and ecosystem for EBS. Fellows benefit from the training in a highly inter­na­tional, inter­dis­ci­pli­nary and inter­sec­toral setting offered by SAL-DC to become future re­search leaders.
Archived project