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Communication Technology Colloquium at IKS

von Irina Ronkartz

Dear subscribers of the colloquium newsletter, we are happy to inform you about the next dates of our Communication Technology Colloquium. *Thursday, October 22, 2020* *Speake**r:* Luis Maßny *Time:* 10:00 a.m. *Location*: https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09 Meeting-ID: 979 0415 7921 Passwort: 481650 *Master Lecture*: Analysis and Optimization of Multi-Kernel Polar Codes Polar codes are a class of linear block codes that exploit the channel polarization effect in order to provide good error correction capabilities at a low complexity. The channel polarization is based on a recursive channel transformation by a so-called polarization kernel. As a generalization of conventional polar codes, multi-kernel polar codes have been proposed, which allow it to combine polarization kernels of different sizes wihtin a single code. Accordingly, these codes provide many degrees of freedom, which makes it important to properly design such a code in order to optimize its performance. Two major aspects of the multi-kernel polar code design are analyzed in this thesis. Firstly, the design of good polarization kernels for practical codeword lengths is studied. Secondly, the effect of applying a chosen set of polarization kernels in different orders is approached. In order to systematically construct polarization kernels, a recursive construction rule is developed that describes each kernel as a concatenation of smaller kernels. The performance analysis is based on the computation of Z parameters of the polarized information bit channels for binary erasure channel. These yield an upper bound on the block error rate. The observations by error rate simulations over an additive white Gaussian noise channel. The results show that the kernel design depends on the code rate. In particular, it is demonstrated that in some cases an asymptotically suboptimal kernel is the best choice. The optimization of the kernel order in general turns out to be complex and depending on a variety of code parameters. and *Thursday, October 22, 2020* *Spe**aker: *Egke Chatzimoustafa *Time:* 11:00 a.m. *Location*: https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09 Meeting-ID: 979 0415 7921 Passwort: 481650 *Bachelor Lecture*: Playback Methods for Multichannel Immersive Binaural Sound Reproducing spatial audio recordings with headphones allows listeners to perceive sound signals in 3D, where the listeners evaluate the differene between the recorded signals at both ears to localize sound sources. For a more immersive reproduction, sound sources should appear fixed in space in the case of head rotations. So for, several immersive reproduction methods like Motion Tracked Binaural Sound (MTB) and Binaural Cue Adaptation (BCA) were proposed. where BCA works with two microphones while MTB requires a larger number of microphones. The goal of this bachelor's thesis is to extend the BCA algorithm for more than two microphones and to evaluate this new multichannel system in terms of source localization and binaural cue modification. The thesis show how additional microphones in the multichannel system can be used to improve the sound source localization. reducing the estimation error also for low Signal-to-Noise Ratio (SNR) values. Furthermore, several experiments show that the additional microphones could solve the front/back confusion and could also discriminate sources that are at the top and bottom, regarding the head model. It is further shown how additional microphones can be employed in the cue modification algorithm. Several experiments confirm that additional microphones could increase the quality, modifying coherent components, and reducing incoherent power error and coherent-to-incoherent power ratio error. As the last extension, an adaptive reference channel selection algorithm is introduced that paramerizes the cue modification based on the optimal reference channel. For larger head movements of the listener, this extension can further improve the quality and even eliminate modification errors for certain head orientations. All interested parties are cordially invited, registration is not required. General information on the colloquium, as well as a current list of the dates of the Communication Technology Colloquium can be found at: http://www.iks.rwth-aachen.de/aktuelles/kolloquium -- Irina Ronkartz Institute of Communication Systems (IKS) RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958 (phone) ronkartz(a)iks.rwth-aachen.de http://www.iks.rwth-aachen.de/

3 Jahre, 6 Monate

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Kommunikationstechnisches Kolloquium am IKS | Communication Technology Colloquium at IKS

von Irina Ronkartz

-- English version below -- Sehr geehrte Abonnenten des Kolloquium-Newsletters, gerne informieren wir Sie über den nächsten Termin unseres Kommunikationstechnischen Kolloquiums. *Montag, 28. September 2020* *Vortragender:* Zach Lee *Zeit:* 11:00 Uhr *Ort*: https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09 Meeting-ID: 979 0415 7921 Passwort: 481650 *Bachelor-Vortrag*: Time-Varying Simulation of Adaptive Crosstalk Cancellation Systems based on Acoustic Measurements In order to reproduce binaural audio via loudspeakers, a crosstalk cancellation (CTC) system is necessary to attenuate the crosstalk. The task is becoming more challenging when the listener is allowed to move, as the CTC system is often robust in a small and limited area. A recent innovative idea known as the adaptive crosstalk cancellation (ACTC) system is proposed. The CTC filter in this system is updated real-time by placing mircophones close to the entrance of the ear canal to measure the signals perceived by the listener and estimate the corresponding head-related impulse response (HRIR). The goal of this thesis is to evaluate the ACTC system by performing an acoustic measurement in an anechoic chamber to obtain the real and accurate HRIR of the test listener. With this knowledge, the performance of the ACTC system can be evaluated in a simulation. Furthermore, the limit of the ACTC system can be tested, in terms of how fast it can adapt to changes. The results show that the ACTC system has a fairly good performance when the listener's ears are on the ipsilateral side of the loudspeakers and the performance falls drastically on the contralateral side. In lower frequencies, the ACTC system works quite well up to a movement (head rotation) speed of 20 deg/s. Alle Interessierten sind herzlich eingeladen, eine Anmeldung ist nicht erforderlich. Allgemeine Informationen zum Kolloquium sowie eine aktuelle Liste der Termine des Kommunikationstechnischen Kolloquiums finden Sie unter: http://www.iks.rwth-aachen.de/aktuelles/kolloquium Dear subscirbers of the colloquium newsletter, we are happy to inform you about the next date of our communication technology colloquium. *Monday, September 28, 2020* *Speaker*: Zach Lee *Time:* 11:00 a.m. *Location*: https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09 Meeting-ID: 979 0415 7921 Passwort: 481650 *Bachelor Lecture*: Time-Varying Simulation of Adaptive Crosstalk Cancellation Systems based on Acoustic Measurements In order to reproduce binaural audio via loudspeakers, a crosstalk cancellation (CTC) system is necessary to attenuate the crosstalk. The task is becoming more challenging when the listener is allowed to move, as the CTC system is often robust in a small and limited area. A recent innovative idea known as the adaptive crosstalk cancellation (ACTC) system is proposed. The CTC filter in this system is updated real-time by placing microphones close to the entrance of the ear canal to measure the signals perceibed by the listener and estimate the corresponding head-related impulse response (HRIR). The goal of this thesis is to evaluate the ACTC system by performing an acoustic measurement in an anechoic chamber to obtain the real and accurate HRIR of the test listener. With this knowledge, the performance of the ACTC system can be evaluated in a simulation. Furthermore, the limit of the ACTC system can be tested, in terms of how fast it can adapt to changes. The results show that the ACTC system has a fairly good performance when the listener's ears are on the ipsilateral side of the loudspeakers and the performance falls drastically on the contralateral side. In lower frequencies, the ACTC system works quite well up to a movement (head rotation) speed of 20 deg/s. All interested parties are cordially invited, registration is not required. General information on the colloquium, as well as a current list of the dates of the communication technology colloquium can be found at: http://www.iks.rwth-aachen.de/aktulles/kolloquium -- Irina Ronkartz Institute of Communication Systems (IKS) RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958 (phone) ronkartz(a)iks.rwth-aachen.de http://www.iks.rwth-aachen.de/

3 Jahre, 7 Monate

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Kommunikationstechnisches Kolloquium am IKS | Communication Technology Colloquium at IKS

von Irina Ronkartz

--- Englich version below --- Sehr geehrte Abonnenten des Kolloquium-Newsletters, gerne informieren wir Sie über den nächsten Termin unseres Kommunikationstechnischen Kolloquiums. *Freitag, 25. September 2020* *Vortr**agende*: Liuhui Deng *Zeit*: 11:00 Uhr *Ort*: https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09 Meeting-ID: 979 0415 7921 Passwort: 481650 *Master-Vortrag*: Speech Inpainting Using Image Processing Techniques Speech inpainting is a task that reconstructs speech from damaged speech signals, wherein corruption can result from improper storage, packet loss in communication networks and etc. Neural networks are becoming an active research hot-spot in the field of audio inpainting in recent years, including speech inpainting, music inpainting and etc. The networks can either be fed waveforms of audio or other feature representations such as Short-Time Frequency Transform (STFT), Mel Frequency Cepstral Coefficients (MFCC) and etc. in order to reconstruct audio. In this thesis, advanced Convolutional Neural Networks (CNNs) based architectures in image inpainting are adopted to the task speech inpainting. The motivation lie in the facts that the neural techniques in image inpainting are well investigated and turn out to be powerful, besides, the task speech inpainting can be interpreted as image inpainting when speech spectrogram is treated as 2-dimensional image. The involving networks are mainly context encoder, context encoder with Generative Adversarial Networks (GANs), EdgeConnect (w / o GANs) and EdgeConnect (with GANs). In this work, context encoder is an encoder decoder architecture and takes as input STFT magnitudes (and ground truth corruption mask) while EdgeConnect is fed additionally edge map of spectrogram in order to alleviate the blurriness issue observed in image inpainting. EdgeConnect (w / o GANs) is composed of two sub-models, both of which are a context encoder. One sub-model is referred to as edge completion model which reconstructs edge map from corrupted edge map and the other is inpainting model which reconstructs spectrogram based on correupted spectrogram and edge map. GANs applied in the models of interest are also intended to mitigate the blurriness by adding adversarial loss from GANs to the loss function of context encoder, edge completion model and inpainting model. Experiments indicate that context encoder (w/ or w/o GANs) outperforms the CNNs which are simply stacking a few convolutional layers. EdgeConnect (w/ or w/o GANs) achieves even better performance than context encoder (w/ or w/o GANs) mainly thanks to additional informative edge map of spectrogram. The best model among them is EdgeConnect (with GANs), its reconstructed speeches achieve 3,03 in terms of PESQ score, 71,2% improvement compared to input corrupted speech. Besides, analyses of edge map quality in EdgeConnect (w/ or w/o GANs) reveal that edge map of low quality heavily degrades the inpainting performance, thus a well performing edge completion model is of great importance and is a promising direction to put more effort into in the future. Alle Interessierten sind herzlich eingeladen, eine Anmeldung ist nicht erforderlich. Allgemeine Informationen zum Kolloquium sowie eine aktuelle Liste der Termine des Kommunikationstechnischen Kolloquiums finden Sie unter: http://www.iks.rwth-aachen.de/aktuelles/kolloquium/ Dear subscribers of the colloquium newsletter, we are happy to inform you about the next date of our communication technology colloquium. *Friday, September 25, 2020* *Speaker*: Liuhui Deng *Time*: 11:00 a.m. *Location*: https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09 Meeting-ID: 979 0415 7921 Passwort: 481650 *Master Lecture*: Speech Inpainting Using Image Processing Techniques Speech inpainting is a task that reconstructs speech from damaged speech signals, wherein corruption can result from improper storage, packet loss in communication networks and etc. Neural networks are becoming an active research hot-spot in the field of audio inpainting in recent years, including speech inpainting, music inpainting and etc. The networks can either be fed waveforms of audio or other feature representations such as Short-Time Frequency Transform (STFT), Mel Frequency Cepstral Coefficients (MFCC) and etc. in order to reconstruct audio. In this thesis, advanced Convolutional Neural Networks (CNNs) based architectures in image inpainting are adopted to the task speech inpainting. The motivation lie in the facts that the neural techniques in image inpainting are well investigated and turn out to be powerful, besides, the task speech inpainting can be interpreted as image inpainting when speech spectrogram is treated as 2-dimensional image. The involving networks are mainly context encoder, context encoder with Generative Adversarial Networks (GANs), EdgeConnect (w / o GANs) and EdgeConnect (with GANs). In this work, context encoder is an encoder decoder architecture and takes as input STFT magnitudes (and ground truth corruption mask) while EdgeConnect is fed additionally edge map of spectrogram in order to alleviate the blurriness issue observed in image inpainting. EdgeConnect (w / o GANs) is composed of two sub-models, both of which are a context encoder. One sub-model is referred to as edge completion model which reconstructs edge map from corrupted edge map and the other is inpainting model which reconstructs spectrogram based on correupted spectrogram and edge map. GANs applied in the models of interest are also intended to mitigate the blurriness by adding adversarial loss from GANs to the loss function of context encoder, edge completion model and inpainting model. Experiments indicate that context encoder (w/ or w/o GANs) outperforms the CNNs which are simply stacking a few convolutional layers. EdgeConnect (w/ or w/o GANs) achieves even better performance than context encoder (w/ or w/o GANs) mainly thanks to additional informative edge map of spectrogram. The best model among them is EdgeConnect (with GANs), its reconstructed speeches achieve 3,03 in terms of PESQ score, 71,2% improvement compared to input corrupted speech. Besides, analyses of edge map quality in EdgeConnect (w/ or w/o GANs) reveal that edge map of low quality heavily degrades the inpainting performance, thus a well performing edge completion model is of great importance and is a promising direction to put more effort into in the future. All interested parties are cordially invited, registration is not required. General information on the colloquium, as well as a current list of the dates of the communication technology colloquium can be found at: http://www.iks.rwth-aachen.de/aktuelles/kolloquium -- Irina Ronkartz Institute of Communication Systems (IKS) RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958 (phone) ronkartz(a)iks.rwth-aachen.de http://www.iks.rwth-aachen.de/

3 Jahre, 7 Monate

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Kommunikationstechnisches Kolloquium am IKS | Communication Technology Colloquium at IKS

von Irina Ronkartz

--- English version below --- Sehr geehrte Abonnenten des Kolloquium-Newsletters, gerne informieren wir Sie über den nächsten Termin unseres Kommunikationstechnischen Kolloquiums. *Montag, 31. August 2020* *Vortragender*: Sumedh J. Dongare *Zeit**:* 14:00 Uhr *Ort*: https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09 Meeting-ID: 979 0415 7921 Passwort: 481650 *Master-Vortrag*: Optimized Compression Functions for Reduced Complexity Informatin Bottleneck Detection and Decoding The detection and the decoding at the receiver side is of crucial importance and often the optimum signal processing algorithms result in high implementation complexity. Therefore, sub-optimal algotihms with close to optimum performance are needid in practice. The information bottleneck method is a novel method for the detection and decoding with the low complexity that maximizes the mutual information. The main idea of such signal processing method is to design mutual information preserving mappings that replace the traditional signal processing operations to reduce complexity. These mappings are typically implemented as look-up tables. For instance, the literature successfully applies this method for the decoding of binary low-density parity-check codes. The low-density parity-check codes are gaining more and more attention since their non-binary generalization has been found out which has better error correction capabilities than their binary equivalents. Due to the advancements in the computational capabilities of the devies, research in this field is a current hot topic. It turns out that the decoding of the non-binary low-density parity-check codes is an application which does not allow the straight forward application of the mutual information maximizing signals processing. The main problems are that the decoding requires systems with many input variables and in addition, the symbols from higher order fields can take more than two values. As a result the look-up table based approach which works well in case of binary codes, here results in look-up of prohibitive size. This motivates me to explore and investigate compression functions which can maximize the relevant mutual information but can be characterized using much fewer parameters than look-up tables. Such functions are designed in this thesis with a novel approach which relies on the genetic algorithms. Such algorithms are inspired from the natural evolution of the species. The novel approach allows to construct and analyze systems which cannot be designed with the look-up table based approach. This thesis compares the resulting systems to other state-of-the-art signal processing systems in terms of symbol error rate performance and also in terms of the ability to preserve relevant mutual information. The refernce system which is considered typically in this thesis is the soft symbol demodulator which has to be applied when non-binary low-density parity-check codes shall be used with binary modulation. Such demodulators designed using the novel approach are compared whith the look-up table based approach and traditonal soft symbol demodulators. The thesis develops a powerful class of parametrizable mappings that can be optimized using the genetic algorithms. Most importantly, the novel approach allows to achieve performance close to that of a soft symbol demodulator in many investigated scenarios. Alle Interessierten sind herzlich eingeladen, eine Anmeldung ist nicht erforderlich. Allgemeine Informationen zum Kolloquium sowie eine aktuelle Liste der Termine des Kommunikationstechnischen Kolloquiums finden Sie unter: httP://www.iks.rwth-aachen.de/aktuelles/kolloquium/ Dear subscribers of the colloquium newsletter, we are happy to inform you about the next date of our communication technology colloquium. *Monday, August 31, 2020* *Speaker*: Sumedh J. Dongare *Time*: 2:00 p.m. *Locatio*n: https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09 Meeting-ID: 979 0415 7921 Passwort: 481650 *Master Lecture*: Optimized Compression Functions for Reduced Complexity Informatin Bottleneck Detection and Decoding The detection and the decoding at the receiver side is of crucial importance and often the optimum signal processing algorithms result in high implementation complexity. Therefore, sub-optimal algotihms with close to optimum performance are needid in practice. The information bottleneck method is a novel method for the detection and decoding with the low complexity that maximizes the mutual information. The main idea of such signal processing method is to design mutual information preserving mappings that replace the traditional signal processing operations to reduce complexity. These mappings are typically implemented as look-up tables. For instance, the literature successfully applies this method for the decoding of binary low-density parity-check codes. The low-density parity-check codes are gaining more and more attention since their non-binary generalization has been found out which has better error correction capabilities than their binary equivalents. Due to the advancements in the computational capabilities of the devies, research in this field is a current hot topic. It turns out that the decoding of the non-binary low-density parity-check codes is an application which does not allow the straight forward application of the mutual information maximizing signals processing. The main problems are that the decoding requires systems with many input variables and in addition, the symbols from higher order fields can take more than two values. As a result the look-up table based approach which works well in case of binary codes, here results in look-up of prohibitive size. This motivates me to explore and investigate compression functions which can maximize the relevant mutual information but can be characterized using much fewer parameters than look-up tables. Such functions are designed in this thesis with a novel approach which relies on the genetic algorithms. Such algorithms are inspired from the natural evolution of the species. The novel approach allows to construct and analyze systems which cannot be designed with the look-up table based approach. This thesis compares the resulting systems to other state-of-the-art signal processing systems in terms of symbol error rate performance and also in terms of the ability to preserve relevant mutual information. The refernce system which is considered typically in this thesis is the soft symbol demodulator which has to be applied when non-binary low-density parity-check codes shall be used with binary modulation. Such demodulators designed using the novel approach are compared whith the look-up table based approach and traditonal soft symbol demodulators. The thesis develops a powerful class of parametrizable mappings that can be optimized using the genetic algorithms. Most importantly, the novel approach allows to achieve performance close to that of a soft symbol demodulator in many investigated scenarios. All interested parties are cordially invited, registration is not required. General information on the colloquium, as well as a current list of the dates of the communication technology colloquium can be found at: http://www.iks.rwth-aachen.de/aktuelles/kolloquium -- Irina Ronkartz Institute of Communication Systems (IKS) RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958 (phone) ronkartz(a)iks.rwth-aachen.de http://www.iks.rwth-aachen.de/

3 Jahre, 8 Monate

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Kommunikationstechnisches Kolloquium am IKS

von Irina Ronkartz

Sehr geehrte Abonnenten des Kolloquium-Newsletters, gerne informieren wir Sie über den nächsten Termin unseres Kommunikationstechnischen Kolloquiums. *Mittwoch, 15. Juli 2020* *Vortragender:* Jérôme Biot *Zeit:* 11:00 Uhr *Ort*: https://rwth.zoom.us/j/97904157921?pwd=SWpsbDl0MWhrWjY1ZkZaeFRoYmErZz09 Meeting-ID: 979 0415 7921 Passwort: 481650 *Master-Vortrag*: Acoustic Head-Tracking in Adaptive Crosstalk Cancellation Systems In order to accurately reproduce an acoustic scene for a listener, a technique known as binaural reproduction is used. A binaural signal consists of two channels containing a different signal for each ear depending on the listener's position relative to the sound source. When trying to replicate a binaural signal over headphones, perfect channel separation is guarantedd, meaning that the binaural signals designated for the left and right ear respectively are only transmitted to the corresponding ear. When a loudspeaker system is used on the other hand, crosstalk between the two binaural signals is an issue and has to be cancelled by the corresponding crosstalk cancellation (CTC) filters. In adaptive crosstalk cancellation (ACTC) systems, these filters are adapted in real-time by placing two microphones close to the ear positions to measure the incoming sound signals and estimate the corresponding impulse responses. The goal of this thesis is to acoustically estimate the position and orientation of a listener's head based on these impulse responses in order to adapt the binaural signals of the acoustic scene. Based on geometric relations in free space, an estimation of the position and orientation of the listener can be done. Several algorithms for 2D and 3D space have been implemented and compared against each other in terms of accuracy and real-time capability. Alle Interessierten sind herzlich eingeladen, eine Anmeldung ist nicht erforderlich. Allgemeine Informationen zum Kolloquium, sowie eine aktuelle Liste der Termine des Kommunikationstechnischen Kolloquiums finden Sie unter: http://www.iks.rwth-aachen.de/aktuelles/kolloquium/ -- Irina Ronkartz Institute of Communication Systems (IKS) RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958 (phone) ronkartz(a)iks.rwth-aachen.de http://www.iks.rwth-aachen.de/

3 Jahre, 9 Monate

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Kommunikationstechnisches Kolloquium am IKS

von Irina Ronkartz

Sehr geehrte Abonnenten des Kolloquium-Newsletters, gerne informieren wir Sie über die nächsten Termine unseres Kommunikationstechnischen Kolloquiums. *Mittwoch, 17. Juni 2020* *Vortragender:* Jingcheng Tian *Zeit:* 11:00 Uhr *Webex Meeting*: https://meetingsemea22.webex.com/meetingsemea22-de/j.php?MTID=md260f6a6859c… Meeting-Kennummer (Zugriffscode): 162 224 7271 Meeting-Passwort: 505027 *Master-Vortrag*: End-to-End Speech Inpainting Using Convolutinal Network Structures Speech signals are often subject to interference or damage in the time or frequency domain during transmission. There are many ways to address these disturbances. One of them is Packet Loss Concealment (PLC), which is a technology designed to minimize the practical effect of lost packets in digital communications. Bandwidth Extension (BWE), on the other hand, is the process of extending the frequency range of a signal. Speech inpainting, a generalized version of BWE and PLC, refers to the loss of the signal at any time and any frequency, rather than a fixed time and frequency. The term inpainting comes from image inpainting, which comprises a subarea of digital image processing, where already many deep learning-based techniques for reconstruction of broken pictures exist. However, in the field of speech, this technology has not been widely spread. Only a few dictionary-based speech signal inpainting approaches exist. In this work we intodruce a model for solving speech inpainting task. Learning-based methods have been proven to have a better performance compared to traditional algorithms in front-end processing, such as speech noise reduction and BWE. However, most algorithms extract features and use magnitude spectrograms as input to the model. One disadvantage of this is the lack of phase information. WaveNet, the very famous model which is used for speech synthesis, uses a dilated CNN to directly generate raw audio. This thesis uses a modified WaveNet to make it directly read raw speech and generate speech, that is, the input and output of the model are lossless and no information is lost. Instead, CNN does the feature extraction automatically in the first layers. At the same time, the huge space complexity required by WaveNet is reduced. In addition, the characteristics of the causality are modified into symmetry. The model can not only see the past information, but also the future information, which increases the receptive field and improves the accuracy of the model. We also introduce different loss functions for comparison. In the experiments, we tried different types of data, different noise, different loss of time and frequency. Computational evaluation shows that this method can reconstruct speech signals, not only in magnitude, but also in phase. und *Mittwoch, 17. Juni 2020* *Vortragender*: Daniel Wilhelm *Zeit:* 14:00 Uhr *Zoom-Meeting*: https://rwth.zoom.us/j/91765335911?pwd=TFFHdTBlWStyR1lVU25IbGdCWmNJdz09 Meeting-ID: 917 6533 5911 Passwort: 297152 *Bachelor-Vortrag*: Rekonstruktion des Phasenspektrums von Sprachsignalen mit Machine-Learning-Algorithmen Die Verarbeitung von Audio- bzw. Sprachsignalen findet häufig im Zeit-Frequenzspektrum statt. Dieses setzt sich zusammen aus dem Magnituden- und dem Phasenspektrum. Da das Magnitudenspektrum relevanter für die Verständlichkeit von Sprachsignalen ist, werden Berechnungen, wie z. B. eine Störgeräuschreduktion, oft nur mit diesem durchgeführt und das Phasenspektrum wird unverändert übernommen. Um eine möglichst optimale Sprachqualität zu erhalten, muss jedoch auch das Phasenspektrum berücksichtigt werden. Eine Möglichkeit ist es, das Phasenspektrum auf Basis des verbesserten Magnitudenspektrums zu rekonstruieren. Ein weit verbreiteter Ansatz hierfür ist der Griffin-Lim-Algorithmus. Dieser ist ein iterativer Algorithmus, der als Eingabe nur das Magnitudenspektrum erhält und sich dann in jedem Schritt mit dem passenden Zeitsignal annähert. Eine hinreichende Sprachqualität erfordert jedoch typischerweise viele Iterationen, die auf das gesamte Signal wirken, was dazu führt, dass ein hoher Rechenaufwand entsteht und der Einsatz in einer Echtzeit-Implementierung erschwert wird. In dieser Arbeit wird daher ein anderer Ansatz zur Rekonstruktion des Phasenspektrums aus dem Magnitudenspektrum eines Sprachsignals entwickelt, bei dem das Phasenspektrum mit Hilfe von einem Machine-Learning-Algorithmus geschätzt wird. Ebenfalls wird die Anwendungsmöglichkeit auf beschädigte Sprachsignale, bei denen Lücken im Zeit-Frequenzspektrum vorhanden sind, untersucht. In dem hier vorgestellten Algorithmus werden die Ableitungen des Phasenspektrums (nach der Zeit und nach der Frequenz) von einem neuronalen Netz geschätzt und danach zu einem möglichst passenden Phasenspektrum zusammengeführt. Es werden passende Vorverarbeitungsschritte für die an das neuronale Netz zu übergebenden Daten gesucht. Eine Reduktion der zu verarbeitenden Datenmenge wird vorgeschlagen, um den Rechenaufwand zu reduzieren. Anschließend werden verschiedene Versuche durchgeführt, um die Schätzung des Phasenspektrums zu verbessern. Dabei werden u.a. die Komplexität und weitere Eigenschaften des neuronalen Netzes variiert, sowie mehrere Möglichkeiten zur Zusammensetzung des Phasenspektrums aus den Phasenableitungen eingesetzt. Ein Vergleich mit dem Griffin-Lim-Algorithmus wird ebenfalls durchgeführt. Zum Abschluss werden beschädigte Sprachsignale betrachtet und die Anwendungsmöglichkeit des erarbeiteten Algorithmus für diesen Fall bewertet. Alle Interessierten sind herzlich eingeladen, eine Anmeldung ist nicht erforderlich. Allgemeine Informationen zum Kolloquium, sowie eine aktuelle Liste der Termine des Kommunikationstechnischen Kolloquiums finden Sie unter: http://www.iks.rwth-aachen.de/aktuelles/kolloquium/ -- Irina Ronkartz Institute of Communication Systems (IKS) RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958 (phone) ronkartz(a)iks.rwth-aachen.de http://www.iks.rwth-aachen.de/

3 Jahre, 10 Monate

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Einladung Promotionsvortrag

von Irina Ronkartz

Sehr geehrte Abonnenten des Kolloquium-Newsletters, gerne laden wir Sie zu einem Promotionsvortrag ein. Vortragender: Herr Stefan Liebich, M. Sc. Thema: *Active Noise and Occlusion Effect Cancellation in Headphones and Hearing Aids* Zeit: Montag, 18. Mai 2020, 11:00 Uhr Zoom-Meeting: https://us02web.zoom.us/j/88156655771 Meeting-ID: 881 5665 5771 Passwort: 471696 The perception of one's own voice is distorted when telephoning with headsets, or wearing hearing aids. The reason for this is the so-called occlusion effect. The ear canals are completely or partially closed by the headset or hearing aid. The occlusion causes amplification of low frequencies, and attenuation of high frequencies of one's own voice. The unnatural perception of one's own voice and of noise caused by chewing and swallowing are among the most common complaints of users. Furthermore, environmental noise might impair perception. In this thesis, both the unnatural perception of one's own voice and the disturbance by environmental noise are tackled by novel signal processing approaches. The proposed solution solves the problem of the occlusion effect by actively emiiting a compensation signal through the integrated loudspeaker. This novel approach combines methods of active noise cancellation (ANC, Noise Cancelling Headphone) with a personalized design. The binaural headset contains two additional microphones per side, one inner and one outer, to acquire signals for the calculation of the compensation signals. A combination of feedback and feedforward digital filters allows for either approaching personal silence or a natural perception of one's own voice and the surroundings. The main contributions are: * Novel design concept for ANC / OEC systems which are robust w.r.t. acoustical variations of ear canals and earpiece fittings * Novel structure for combined feedback-feedforward filters with adaptive stability control * Analysis of variability of acoustic front-end (headset) as well as electronics back-end (digital signal processing incl. AD/DA-conversion) and implications on ANC/OEC performance * Real-time implementation, instrumental and auditive evaluations The achieved ANC performance is comparable to that of a commercial reference system. The OEC performance revealed in both objective measurements and subjective listening tests, significant improvements of the own-voice perception. Alle Interessierten sind herzlich eingeladen, eine Anmeldung ist nicht erforderlich. -- Irina Ronkartz Institute of Communication Systems (IKS) RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958 (phone) ronkartz(a)iks.rwth-aachen.de http://www.iks.rwth-aachen.de/

3 Jahre, 11 Monate

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Kommunikationstechnisches Kolloquium am IKS | online | geänderte Anfangszeit

von Irina Ronkartz

Sehr geehrte Abonnenten des Kolloquium-Newsletters, u.a. finden Sie den Link zur Videokonferenz zum Mastervortrag von Nikita Airee. Bitte beachten Sie, dass, aufgrund Überlastung des Systems, die Anfangszeit auf 8:30 Uhr vorverlegt wurde. viele Grüße Irina Ronkartz -------- Original-Nachricht -------- Betreff: Final Presentation Master Thesis Nikita Airee Datum: Dienstag, März 24, 2020 09:50 CET Von: "Adrat, Marc" <marc.adrat(a)fkie.fraunhofer.de> An: Christiane Antweiler <antweiler(a)iks.rwth-aachen.de>, Irina Ronkartz <ronkartz(a)iks.rwth-aachen.de>, Peter Jax <jax(a)iks.rwth-aachen.de>, "Nikita Airee" <nikitaairee(a)gmail.com>, "Saha, Souradip" <souradip.saha(a)fkie.fraunhofer.de>, Souradip Saha <souradipsaha128(a)gmail.com>, "Antweiler, Markus" <markus.antweiler(a)fkie.fraunhofer.de> Topic: Optimized Power Allocation in NOMA-based Overlay Cognitive Radio Network ***DO NOT DELETE OR CHANGE ANY OF THE TEXT BELOW THIS LINE*** Marc Adrat has scheduled this WebEx meeting. Final Presentation Master Thesis Nikita Airee Host: Marc Adrat When it's time, start or join the WebEx meeting from here: https://conference.fraunhofer.de/orion/joinmeeting.do?MTID=d6d66de63cb6b5c3… Access Information Meeting Number: 992 502 355 Meeting Password: (This meeting does not require a password.) Audio Connection +4971197077777 (WebEx) Access Code: 992 502 355 Hosts, need your host access code or key? Go to the meeting information page: https://conference.fraunhofer.de/orion/meeting/meetingInfo?MTID=5fbce4dbf75… The conference.fraunhofer.de team Need help? https://www.fraunhofer.de/ -------- Original-Nachricht -------- Betreff: Kommunikationstechnisches Kolloquium am IKS | online Datum: Montag, März 23, 2020 12:07 CET Von: Irina Ronkartz <ronkartz(a)iks.rwth-aachen.de> An: kommunikationstechnik-kolloquium(a)lists.rwth-aachen.de Sehr geehrte Abonnenten des Kolloquium-Newsletters, gerne informieren wir Sie über den nächsten Termin unseres Kommunikationstechnischen Kolloquiums. Freitag, 27. März 2020 Vortragende: Nikita Airee Ort: online Zeit: 10:30 Uhr | neue Startzeit 8:30 Uhr Master-Vortrag: Optimized Power Allocation on NOMA-based Overlay Cognitive Radio Networks Spectral efficiency (SE) is crucial for wireless networks due to the scarcity of wireless spectrum and the ever increasing number of users that need access to it. Cognitive radios (CRs) are a prominent solution for SE as they facilitate spectrum sharing between tow or more users. Another technique for improving SE, which has recently come in to focus, os nonorthogonal multiple access (NOMA). Together, they have immense potential for enabling highly spectrally efficient communication. A type of NOMA called power domain nonorthogonal multiple access (PD-NOMA) has been considered in downlink for a CR network in this thesis. PD-NOMA is essentially a multiple access (MA) technique that multiplexes the signals for users in the power domain. Hence, the division of power among the user signals is a critical PD-NOMA process known as power allocation (PA). In this thesis, two methods for PA have been proposed namely, k-scaled PA and fair PA. The performance of the users in the CR network for each of these methods has been extensively evaluated. It has been noted that k-scaled PA reduces the information overhead when there are a large number of users in the network. While it has also been observed to be robust against interference, k-scaled PA method does not always lead to optimum power division. Therefore, fair PA has been proposed for achieving similar performance at all the users. However, it is only applicable for users with specific channel conditions. Also, up to 5 users have been accommodated in the network using the k-scaled method, enabling communicatin over the same spectral resource. Alle Interessierten sind herzlich eingeladen, der Vortrag findet online statt, der Link dazu wird am Donnerstag verschickt. Allgemeine Informationen zum Kolloquium, sowie eine aktuelle Liste der Termine des Kommunikationstechnischen Kolloquiums finden Sie unter: http://www.iks.rwth-aachen.de/aktuelles/kolloquium-- Irina Ronkartz Institute of Communication Systems (IKS) RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958 (phone) ronkartz(a)iks.rwth-aachen.de http://www.iks.rwth-aachen.de/

4 Jahre, 1 Monat

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Kommunikationstechnisches Kolloquium am IKS | online

von Irina Ronkartz

Sehr geehrte Abonnenten des Kolloquium-Newsletters, gerne informieren wir Sie über den nächsten Termin unseres Kommunikationstechnischen Kolloquiums. *Freitag, 27. März 2020* *Vortragende*: Nikita Airee *Ort:* online *Zeit:* 10:30 Uhr *Master-Vortrag*: Optimized Power Allocation on NOMA-based Overlay Cognitive Radio Networks Spectral efficiency (SE) is crucial for wireless networks due to the scarcity of wireless spectrum and the ever increasing number of users that need access to it. Cognitive radios (CRs) are a prominent solution for SE as they facilitate spectrum sharing between tow or more users. Another technique for improving SE, which has recently come in to focus, os nonorthogonal multiple access (NOMA). Together, they have immense potential for enabling highly spectrally efficient communication. A type of NOMA called power domain nonorthogonal multiple access (PD-NOMA) has been considered in downlink for a CR network in this thesis. PD-NOMA is essentially a multiple access (MA) technique that multiplexes the signals for users in the power domain. Hence, the division of power among the user signals is a critical PD-NOMA process known as power allocation (PA). In this thesis, two methods for PA have been proposed namely, /k/-scaled PA and fair PA. The performance of the users in the CR network for each of these methods has been extensively evaluated. It has been noted that /k/-scaled PA reduces the information overhead when there are a large number of users in the network. While it has also been observed to be robust against interference, /k/-scaled PA method does not always lead to optimum power division. Therefore, fair PA has been proposed for achieving similar performance at all the users. However, it is only applicable for users with specific channel conditions. Also, up to 5 users have been accommodated in the network using the /k/-scaled method, enabling communicatin over the same spectral resource. *Alle Interessierten sind herzlich eingeladen, der Vortrag findet online statt, der Link dazu wird am Donnerstag verschickt. * Allgemeine Informationen zum Kolloquium, sowie eine aktuelle Liste der Termine des Kommunikationstechnischen Kolloquiums finden Sie unter: http://www.iks.rwth-aachen.de/aktuelles/kolloquium -- Irina Ronkartz Institute of Communication Systems (IKS) RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958 (phone) ronkartz(a)iks.rwth-aachen.de http://www.iks.rwth-aachen.de/

4 Jahre, 1 Monat

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Kommunikationstechnisches Kolloquium am IKS

von Irina Ronkartz

Sehr geehrte Abonnenten des Kolloquium-Newsletters, gerne informieren wir Sie über den nächsten Termin unseres Kommunikationstechnischen Kolloquiums. *Freitag, 7. Februar 2020* *Vortragende*: Bingying Qin *Ort:* Hörsaal 4G *Zeit:* 10:00 Uhr *Master-Vortrag*: Acquisition of Individual HRTFs using Acoustic Headtracking Virtual reality is now widely applied in different areas. Headphone-based binaural rendering is commonly used to reconstruct the sound in a virtual environment. Head-Related Transfer Functions (HRTs) is essential in the sound reconstruction. Using individual HRTF database can achieve a better experience in the sound simulation. The demands for individual HRTF database increase rapidly. The proposed dynamic measurement with acoustic head tracking provides a fast and easy method to obtain individual HRTFs. This thesis proposes a processing procedure to get individual HRTF database from the HRTFs measured using acoustic head tracking. The processing procedure constructs a desired, usually regularly spaced HRTF data set from the irregularly spaced measurement results. The relations between the sound source positions are quantified in weights and the weights are used in the HRTF interpolation. Interpolation algorithm with separated amplitude and phase interpolation is illustrated. Measurements performed in IKS|Lab using acoustic head tracking proves that the interpolation works well. Alle Interessierten sind herzlich eingeladen, eine Anmeldung ist nicht erforderlich. Allgemeine Informationen zum Kolloquium, sowie eine aktuelle Liste der Termine des Kommunikationstechnischen Kolloquiums finden Sie unter: http://www.iks.rwth-aachen.de/aktuelles/kolloquium/ -- Irina Ronkartz Institute of Communication Systems (IKS) RWTH Aachen University Muffeter Weg 3a, 52074 Aachen, Germany +49 241 80 26958 (phone) ronkartz(a)iks.rwth-aachen.de http://www.iks.rwth-aachen.de/

4 Jahre, 3 Monate

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