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.
*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