About Me

I am a Senior Researcher in the field of fiber-optic communications. My research deals with coded modulation, constellation shaping, and general information-theoretic aspects of nonlinear fiber optics.

News and Updates

TCOM Paper Accepted – November 6, 2018

Our paper "Multiset-partition distribution matching" has been accepted for publication in the IEEE Transactions on Communications. This is joint work with  Dave Millar and colleagues from Mitsubishi Electric Research Laboratories. The PDF of the paper can be found here.

TPC Member of SPPCom 2019 – October 7, 2018

I will serve on the technical program committee of the 2019  Signal Processing in Photonic Communications (SPPCom) conference in California, USA.

Award for Dissertation – October 7, 2018

I will receive the 2018 dissertation award by the Information Technology Society (ITG) within the VDE, see  here for details.

New Preprint

The preprint on  Partition-Based Distribution Matching is available on arXiv. This is joint work with David S. Millar, Toshiaki Koike-Akino, Keisuke Kojima, and Kieran Parsons from  MERL.

Updated Website – January 5, 2018

This website has been slightly updated. My CV is now up-to-date, and a few publications from the last months have been included.

Dr.-Ing. – December 28, 2017

After successfully passing my PhD defense and submitting the print-outs of my thesis to the TUM library, I am finally done with my PhD. A PDF version of my thesis will be available shortly.

Contact

Tobias Fehenberger

Dr.-Ing. Tobias Fehenberger
Senior Researcher
Tel: +49-89-89067681
Email: tobias.fehenberger@ieee.org

About Me

Personal

I received my Dipl.-Ing. and Dr.-Ing. in Electrical Engineering and Information Technology from TUM in 2011 and 2017, respectively. I also have a B.Sc. in Management and Technology from TUM. I studied abroad at the American University of Beirut, Lebanon, and did my Master Thesis at the Optical Networks Group at University College London (UCL), UK. From 2012 to 2017, I was a Research and Teaching Assistant at the TUM Institute for Communications Engineering. Until August 2018, I was a Senior Researcher at TUM. Currently, I am on parental leave.

In my free time, I enjoy nature: hunting, hiking, and fishing.

My Research

I investigate optical communication systems, which have become the backbone of the digital age. Virtually all IP-based traffic of the Internet is transmitted over optical fibers, enabling high data rate services such as HD video streaming and cloud storage. The low loss of optical fibers over a huge spectrum of several THz and optical wideband amplifiers are key technologies that enable transmission of several trillion bits (Terabits) per second over thousands of kilometers of single-mode optical fiber with a core thinner than a human hair. Although these capacities seem huge, a steady demand for increased throughput has been observed for the past decades, with no end in sight. High-order modulation formats and advanced forward error correction schemes are potential options to achieve larger data rates. My research addresses these two entities jointly, a field known as coded modulation.

Google Scholar profile
ResearchGate profile

Education

  • 2017: Dr.-Ing. (summa cum laude), TUM
  • 2017: B.Sc. in Management and Technology, TUM
  • 2011: Dipl.-Ing. (with distinction) in Electrical Engineering and Information Technology, TUM
  • 2005: Abitur (high school diploma equivalent), Karlsgymnasium München

Prizes and Awards

  • 2018: Dissertation award for outstanding thesis by the Information Technology Society (ITG) within the VDE [ more] [Image]
  • 2018: Friedrich-von-Klinggräff Medal of the Stifterverein Alter Corpsstudenten
  • 2017: Graduate Student Fellowship Award by the IEEE Photonics Society for “very impressive accomplishments and academic record”
  • 2017: German representative at Photonics Global Student Conference, Singapore. Nominated for research achievements in the field of photonics [Image]
  • 2017: TUM Grad School EuroTech travel grant to support research visit to Information and Communication Theory Lab at TU Eindhoven, The Netherlands
  • 2015: Teaching excellence prize by the TUM President and Board of Directors for outstanding achievements in and advancement of academic teaching at TUM [German Certificate (PDF)]
  • 2015: Teaching award of the TUM Electrical Engineering student association ("Dozentenpreis der Fachschaft") [Image 1] [Image 2]
  • 2014: Prof. Dr. Ralf Kötter memorial award for my Master Thesis [German newspaper article (PDF)]
  • 2011: Erasmus exchange student at UCL
  • 2011: Scholar of the Heinrich und Lotte Mühlfenzl foundation to carry out my Master Thesis in London
  • 2008: TUM future@home innovation prize

Teaching

Publications

A list of my publications as PDF can be found here. I also have a  Google Scholar profile.

Preprints

  • D. S. Millar, T. Fehenberger, T. Koike-Akino, K. Kojima, and K. Parsons, "Distribution matching for high spectral efficiency optical communication with multiset partitions," Aug. 2018.

2018

  • T. Fehenberger, D. S. Millar, T. Koike-Akino, K. Kojima, and K. Parsons, "Multiset-partition distribution matching," accepted for publication in IEEE Trans. on Commun., Nov. 2018. [PDF] [ arXiv]
  • D. S. Millar, T. Fehenberger, T. Koike-Akino, K. Kojima, and K. Parsons, "Partition based distribution matcher for probabilistic constellation shaping," US Patent 10,069,519, Sep. 2018. [ patents.google.com]
  • D. S. Millar, T. Fehenberger, T. Koike-Akino, K. Kojima, and K. Parsons, "Coded modulation for next-generation optical communications," Proc. Optical Fiber Communication Conference (OFC), San Diego, CA, USA, Mar. 2018. [ DOI]
  • A. Alvarado, T. Fehenberger, B. Chen, and F. M. J. Willems, "Achievable information rates for fiber optics: applications and computations," Journal of Lightwave Technology, vol. 36, no. 2, pp. 424–439, Jan. 2018. [ DOI]
  • T. Fehenberger, "Information rates of probabilistically shaped coded modulation for a multi-span fiber-optic communication system with 64QAM," Optics Communications, vol. 409, pp. 2–6, Feb. 2018. [ DOI]

2017

  • J. Renner, T. Fehenberger, M. P. Yankov, F. Da Ros, S. Forchhammer, G. Böcherer, and N. Hanik, "Experimental comparison of probabilistic shaping methods for unrepeated fiber transmission," Journal of Lightwave Technology, vol. 35, no. 22, pp. 4871–4879, Nov. 2017.  [PDF] [ DOI] [ arXiv]
  • A. Alvarado, G. Liga, T. Fehenberger, and L. Schmalen, "On the design of coded modulation for fiber optical communications," in Proc. Signal Processing in Photonic Communications (SPPCom), New Orleans, LA, USA, Jul. 2017. [ DOI]
  • M. P. Yankov, F. Da Ros, E. P. da Silva, T. Fehenberger, L. Barletta, D. Zibar, L. K. Oxenløwe, M. Galili, and S. Forchhammer, "Nonlinear phase noise compensation in experimental WDM systems with 256QAM," Journal of Lightwave Technology, vol. 35, no. 8, pp. 1438–1443, Apr. 2017.  [ DOI]
  • T. A. Eriksson, T. Fehenberger, and W. Idler, "Characterization of nonlinear fiber interactions using multidimensional mutual information over time and polarization," Journal of Lightwave Technology, vol. 35, no. 6, pp. 1204–1210, Mar. 2017. [ DOI]
  • T. Fehenberger, A. Alvarado, G. Böcherer, and N. Hanik, "On the impact of probabilistic shaping on SNR and information rates in multi-span WDM systems," Proc. Optical Fiber Communication Conference (OFC), Los Angeles, CA, USA, Mar. 2017. [PDF] [ DOI]

2016

  • T. Fehenberger, A. Alvarado, G. Böcherer, and N. Hanik, "On probabilistic shaping of quadrature amplitude modulation for the nonlinear fiber channel," Journal of Lightwave Technology, vol. 34, no. 22, pp. 5064–5074, Nov. 2016. [PDF] [ DOI] [ arXiv]
  • T. Fehenberger, M. Mazur, T. A. Eriksson, M. Karlsson, and N. Hanik, "Experimental analysis of correlations in the nonlinear phase noise in optical fiber systems," Proc. European Conference on Optical Communication (ECOC), Düsseldorf, Germany, Sep. 2016. [PDF] [ IEEEXplore]
  • T. A. Eriksson and T. Fehenberger, "Mutual information characterization of nonlinear fiber channels [invited]," Proc. European Conference on Optical Communication (ECOC), Düsseldorf, Germany, Sep. 2016. [ IEEEXplore]
  • A. Alvarado, L. Szczecinski, T. Fehenberger, M. Paskov, and P. Bayvel, "Improved soft-decision forward error correction via post-processing of mismatched log-likelihood ratios," Proc. European Conference on Optical Communication (ECOC), Düsseldorf, Germany, Sep. 2016. [ IEEEXplore]
  • R. Maher, D. Lavery, G. Liga, M. Paskov, A. Alvarado, T. Fehenberger, and P. Bayvel, "Capacity approaching transmission using probabilistic shaping and DBP for PFE constrained submarine optical links," Proc. European Conference on Optical Communication (ECOC), Düsseldorf, Germany, Sep. 2016. [ IEEEXplore]
  • M. P. Yankov, F. Da Ros, E. P. da Silva, T. Fehenberger, L. Barletta, D. Zibar, L. K. Oxenløwe, M. Galili, and S. Forchhammer, "Experimental study of nonlinear phase noise and its impact on WDM systems with DP-256QAM," Proc. European Conference on Optical Communication (ECOC), Düsseldorf, Germany, Sep. 2016. [ IEEEXplore]
  • T. A. Eriksson, A. Lorences-Riesgo, P. Johannisson, T. Fehenberger, P. A. Andrekson, and M. Karlsson, "Achievable rates comparison for phase-conjugated twin-waves and PM-QPSK," Proc. Optoelectronics and Communications Conference (OECC), Niigata, Japan, Jul. 2016. [ IEEEXplore]
  • T. Fehenberger and N. Hanik, "Multi-dimensional demappers for optical fiber systems with soft-decision forward error correction [invited]," Proc. International Conference on Transparent Optical Networks (ICTON), Trento, Italy, Jul. 2016. [PDF] [ DOI]
  • T. A. Eriksson, T. Fehenberger, P. A. Andrekson, M. Karlsson, N. Hanik, and E. Agrell, "Impact of 4D channel distribution on the achievable rates in coherent optical communication experiments," Journal of Lightwave Technology, vol. 34, no. 9, pp. 2256–2266, May 2016. [ DOI] [ arXiv]
  • T. Fehenberger, T. A. Eriksson, A. Alvarado, M. Karlsson, E. Agrell, and N. Hanik, "Improved achievable information rates by optimized four-dimensional demappers in optical transmission experiments," Proc. Optical Fiber Communication Conference (OFC), Anaheim, CA, USA, Mar. 2016. [PDF]
  • T. Fehenberger, D. Lavery, R. Maher, A. Alvarado, P. Bayvel, and N. Hanik, "Sensitivity gains by mismatched probabilistic shaping for optical communication systems," Photonics Technology Letters, vol. 28, no. 7, pp. 786–789, Apr. 2016. [PDF] [ DOI] [ arXiv]

2015

  • M. P. Yankov, T. Fehenberger, L. Barletta, and N. Hanik, "Low-complexity tracking of laser and nonlinear phase noise in WDM optical fiber systems," Journal of Lightwave Technology, vol. 33, no. 23, pp. 4975–4975, Dec. 2015. [ DOI]
  • T. Fehenberger, M. P. Yankov, L. Barletta, and N. Hanik, "Compensation of XPM interference by blind tracking of the nonlinear phase in WDM systems with QAM input," Proc. European Conference on Optical Communication (ECOC), Valencia, Spain, Sep. 2015. [PDF] [ DOI]
  • T. A. Eriksson, T. Fehenberger, N. Hanik, P. A. Andrekson, M. Karlsson, and Erik Agrell, "Four-dimensional estimates of mutual information in coherent optical communication experiments," Proc. European Conference on Optical Communication (ECOC), Valencia, Spain, Sep. 2015. [PDF] [ DOI]
  • T. Fehenberger, T. A. Eriksson, P. Johannisson, M. Karlsson, and N. Hanik, "On the impact of carrier phase estimation on phase correlations in coherent fiber transmission," Proc. Tyrrhenian International Workshop on Digital Communications (TIWDC), Florence, Italy, Sep. 2015. [PDF] [ DOI]
  • T. Fehenberger and N. Hanik, "Analysis of forward error correction and achievable rates for optical fiber systems [invited]," Proc. International Conference on Transparent Optical Networks (ICTON), Budapest, Hungary, Jul. 2015. [PDF] [ DOI]
  • T. Fehenberger, A. Alvarado, P. Bayvel, and N. Hanik, "On achievable rates for long-haul fiber-optic communications," Optics Express, vol. 23, no. 7, pp. 9183–9191, Apr. 2015. [PDF] [ DOI]
  • T. Fehenberger, G. Böcherer, A. Alvarado, and N. Hanik, "LDPC coded modulation with probabilistic shaping for optical fiber systems," Proc. Optical Fiber Communication Conference (OFC), Los Angeles, CA, USA, Mar. 2015. [PDF] [ DOI]

2014

  • T. Fehenberger and N. Hanik, "Digital back-propagation of a superchannel: achievable rates and adaption of the GN Model," Proc. European Conference on Optical Communication (ECOC), Cannes, France, Sep. 2014. [PDF] [ DOI]
  • T. Fehenberger and N. Hanik, "Estimates of constrained coded modulation capacity for optical networks," Proc. 15. ITG Fachtagung Photonische Netze, Leipzig, Germany, May 2014. [PDF] [ IEEEXplore]

2013

  • T. Fehenberger and N. Hanik, "Information quality (IQ) factor as soft-decision decoding threshold for optical communications," Proc. European Conference on Optical Communication (ECOC), London, UK, Sep. 2013. [PDF] [ DOI]
  • T. Fehenberger and N. Hanik, "Comparison of performance limits by mutual information and practical realizations for optical long-haul coded modulation communication systems [invited]," Proc. International Conference on Transparent Optical Networks (ICTON), Cartagena, Spain, Jun. 2013. [PDF] [ DOI]

2012

  • S. Kilmurray, T. Fehenberger, P. Bayvel, and R. Killey, "Nonlinear transmission performance of reduced guard interval OFDM and quasi-Nyquist WDM," Proc. Signal Processing in Photonic Communications (SPPCom), paper SpTu1A.3, Colorado Springs, CO, USA, Jun. 2012. [ DOI]
  • S. Kilmurray, T. Fehenberger, P. Bayvel, and R. Killey, "Comparison of the nonlinear transmission performance of quasi-Nyquist WDM and reduced guard interval OFDM," Optics Express, vol. 20, no. 4, pp. 4198–4205, Feb. 2012. [ DOI]

Source Code

In this section, you find some Matlab™ source code that I found useful for my research. If you find an error or have a question, please let me know via email.

Achievable Rates: MI and GMI

Calculate Mutual Information (MI): calcMI_MC.m (Sep 10, 2015)
Calculate Generalized Mutual Information (GMI): calcGMI.m (May 29, 2015)

When to use (symbolwise) MI and when to use GMI

For a given input and a memoryless channel, the MI is the largest achievable rate. If you do not want to make restrictions on the receiver and its decoder, use MI. If you consider a receiver with binary decoding and iterations between demapper and decoder are not allowed, GMI is an achievable rate (MI is in general not!).

Gaussian Noise (GN) Model

Calculate (O)SNR according to the GN model: calcOSNR_GNmodel.m (April 28, 2015)