Foto von Daniel Plabst

M.Sc. Daniel Plabst

Technische Universität München

Professur für Leitungsgebundene Übertragungstechnik (Prof. Hanik)


Theresienstr. 90
80333 München


I received my M.Sc. degree from the Technical University of Munich (TUM) in 2018.

In my Master's thesis I worked on signal processing for energy-efficient wireless communication systems at the Associate Professorship of Signal Processing (MSV), while staying with the Wireless Networking and Communications Group at the University of Texas at Austin (UT), USA.

Since 2019 I am a research assistant at the Institute for Communications Engineering in the group Line Transmission Technology of Prof. Dr.-Ing. Norbert Hanik.

Research Interests

Direct-Detection (DD) is a cost-effective approach for short-reach fiber-optic communication. A DD receiver uses a single photodiode to measure the intensity of the impinging signal. This suggests that DD is not compatible with phase modulation. However, using oversampling, the phase can be recovered by exploiting inter-symbol interference (ISI).

We investigate DD for short-reach communication in the context of information theory and estimation strategies.


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Channel Shortening


This topic is offered as part of the Seminar on Digital Communications course.

Satellite channels and long-haul fiber-optic channels are two examples where transmitted signals exhibit excessive inter-symbol interference (ISI).

The mutual information between channel input X and channel output Y describes a reliable communication rate. This rate is achievable when the decoder uses the probabilistic channel description as a decoding metric. However, for excessive ISI the complexity of optimal decoders quickly becomes prohibitive and one must often resort to mismatched decoding by considering a truncated channel impulse response. Clearly, omitting a large number of channel taps impacts system performance.

Linear channel shortening was first considered in the early 70s for maximum-likelihood (ML) sequence detection. A channel shortener "compresses" the channel memory prior to ML detection and the detector can then run with a reduced number of effective channel taps. This significantly reduces computational cost.

Previously, channel shortening filters were derived using the mean squared error (MSE) as a surrogate function. In [1,2] a lower bound on the mutual information was used to optimize channel shorteners for channels with AWGN and Gaussian inputs X.  

[1] F. Rusek and A. Prlja, "Optimal Channel Shortening for MIMO and ISI Channels," in IEEE Transactions on Wireless Communications, vol. 11, no. 2, pp. 810-818, February 2012, doi: 10.1109/TWC.2011.121911.110809.

[2] G. Colavolpe, A. Modenini and F. Rusek, "Channel Shortening for Nonlinear Satellite Channels," in IEEE Communications Letters, vol. 16, no. 12, pp. 1929-1932, December 2012, doi: 10.1109/LCOMM.2012.102612.121929.


  • Linear Algebra
  • Information Theory


SDM for Fiber-Optic Links with Direct Detection


Two work is two-fold:

  • Physically consistent modelling of space division multiplexing (SDM) over a short-reach multimode fiber, including direct detection (DD) per mode.
  • a) Analysis of achievable rates, simple upper and lower bounds on capacity for SDM with DD.
  • b) (MIMO) Equalization for SDM with DD.


Rates for Short-Reach Fiber-Optic Links with Direct Detection


The topic deals with maximizing the generalized mutual information (GMI) for short-reach fiber-optic links. In particular, we are interested in jointly optimizing transmit and receive filters.




  • Plabst, D.; Prinz, T.; Wiegart, T.; Rahman, T.; Stojanovic, N.; Calabro, S.; Hanik, N.; Kramer, G.: Achievable Rates for Short-Reach Fiber-Optic Channels with Direct Detection. IEEE/OSA J. Lightw. Technol., 2022 mehr… Volltext ( DOI )
  • Prinz, T.; Wiegart, T.; Plabst, D.; Rahman, T.; Hossain, S.; Stojanović, N.; Calabrò, S.; Hanik, N.; Kramer, G.: Comparison of PAM-6 Modulations for Short-Reach Fiber-Optic Links with Intensity Modulation and Direct Detection. European Conference on Optical Communication (ECOC) 2022, 2022 mehr… Volltext ( DOI )
  • Wiegart, T.; Plabst, D.; Prinz, T.; Rahman, T.; Schädler, M.; Stojanović, N.; Calabrò, S.; Hanik, N.; Kramer, G.: Experiments on Bipolar Transmission with Direct Detection. European Conference on Optical Communication (ECOC) 2022, 2022 mehr… Volltext ( DOI )


  • Mezghani A., Plabst D., Swindlehurst L. A. , Fijalkow I., Nossek J. A.: Sparse Linear Precoders for Mitigating Nonlinearities in Massive MIMO. IEEE Statistical Signal Processing Workshop 2021, 2021 mehr…
  • Prinz, T.; Wiegart, T.; Plabst, D.; Calabrò, S.; Böcherer, G.; Stojanovic, N.; Rahman, T.;: PAM-6 Coded Modulation for IM/DD Channels with a Peak-Power Constraint. International Symposium on Topics in Coding (ISTC) 2021, 2021 mehr…
  • Wiegart, T.; Prinz, T.; Plabst, D.: Recovering the Phase in DD Receivers with Oversampling: A Toy Example. Huawei Joint Lab Workshop, 2021 mehr…


  • Benedikt Leible, Daniel Plabst, Norbert Hanik: Back-to-Back Performance of the Full Spectrum Nonlinear Fourier Transform and Its Inverse. Entropy 22 (10), 2020, 1131 mehr… Volltext ( DOI ) Volltext (mediaTUM)
  • Benedikt Leible, Daniel Plabst, Norbert Hanik: Stability of the Full Spectrum Nonlinear FourierTransform. International Conference on Transparent Optical Networks (ICTON) 2020, 2020 mehr… Volltext (mediaTUM)
  • Plabst, D.; Hanik, N.: Phase-Retrieval for Short-Reach IM/DD Links. Workshop der Informationstechnischen Gesellschaft (ITG) in Karlsruhe, 2020 mehr…
  • Plabst, Daniel; García-Gómez, Francisco Javier; Wiegart, Thomas; Hanik, Norbert: Wiener Filter for Short-Reach Fiber-Optic Links. IEEE Communications Letters 24 (11), 2020, 2546 - 2550 mehr… Volltext ( DOI )


  • Plabst, D.; Jedda, H.; Mezghani A.: Linear Transmit Signal Processing in 1-Bit Quantized Massive MIMO Systems. 2019 Munich Doctoral Seminar on Communications, 2019 mehr… Volltext (mediaTUM)


  • Munir, J.; Plabst, D.; Nossek, J.A.: Efficient Equalization Method for Cyclic Prefix-Free Coarsely Quantized Massive MIMO Systems. 2018 IEEE International Conference on Communications (ICC), 2018 mehr… Volltext ( DOI )
  • Plabst, D.; Munir J.; Mezghani A.; Nossek, J.A.: Efficient Non-linear Equalization for 1-bit Quantized Cyclic Prefix-Free Massive MIMO Systems. 2018 15th International Symposium on Wireless Communication Systems (ISWCS), 2018 mehr… Volltext ( DOI )