Newsletter des Sonderforschungsbereichs 912 "Highly Adaptive Energy-Efficient Computing" (HAEC)

Sound criteria for partial order reduction for probabilistic concurrent systems have been presented in the literature. Their realization relies on a depth-first search-based approach for generating the reduced model. The drawback of this dynamic approach is that it can hardly be combined with other techniques to tackle the state explosion problem, e.g., symbolic probabilistic model checking with multi-terminal variants of binary decision diagrams. Following the approach presented by Kurshan et al. for non-probabilistic systems, we study partial order reduction techniques for probabilistic concurrent systems that can be realized by a static analysis. The idea is to inject the reduction criteria into the control flow graphs of the processes of the system to be analyzed. We provide the theoretical foundations of static partial order reduction for probabilistic concurrent systems and present algorithms to realize them. Finally, we report on some experimental results.

In heterogeneous dense networks where spectrum is shared, users privacy remains one of the major challenges. When the receivers are not only interested in their own signals but also in eavesdropping other users' signals, the cross talk becomes information leakage.We propose a novel and efficient secrecy rate enhancing relay strategy EFFIN for information leakage neutralization. The relay matrix is chosen such that the effective leakage channel (spectral and spatial) is zero. Thus, it ensures secrecy regardless of receive processing employed at eavesdroppers and does not rely on wiretaps codes to ensure secrecy, unlike other physical layer security techniques such as artificial noise. EFFIN achieves a higher sum secrecy rate over several state-of-the-art baseline methods.

We compare LDPC block and LDPC convolutional codes with respect to their decoding performance under low decoding latencies. Protograph based regular LDPC codes are considered with rather small lifting factors. LDPC block and convolutional codes are decoded using belief propagation. For LDPC convolutional codes, a sliding window decoder with different window sizes is applied to continuously decode the input symbols. We show the required Eb/N0 to achieve a bit error rate of 10 -5 for the LDPC block and LDPC convolutional codes for the decoding latency of up to approximately 550 information bits. It has been observed that LDPC convolutional codes perform better than the block codes from which they are derived even at low latency. We demonstrate the trade off between complexity and performance in terms of lifting factor and window size for a fixed value of latency. Furthermore, the two codes are also compared in terms of their complexity as a function of Eb/N0. Convolutional codes with Viterbi decoding are also compared with the two above mentioned codes.

Communications receivers that rely on 1-bit analogto-digital conversion are advantageous in terms of hardware complexity and power dissipation. Performance limitations due to the 1-bit quantization can be tackled with oversampling. This paper considers the oversampling gain from an information-theoretic perspective by analyzing the channel capacity with 1-bit quantization and oversampling at the receiver for the particular case of AWGN channels. This includes a numerical computation of the capacity and optimal transmit symbol constellations, as well as the derivation of closed-form expressions for large oversampling ratios and for high signal-to-noise ratios of the channel.

1-bit analog-to-digital conversion is very attractive for low-complexity communications receivers. A major drawback is, however, the small spectral efficiency when sampling at symbol rate. This can be improved through oversampling by exploiting the signal distortion caused by the transmission channel. This paper analyzes the achievable data rate of band-limited communications channels that are subject to additive noise and inter-symbol-interference with 1-bit quantization and oversampling at the receiver. It is shown that not only the channel noise but also the inter-symbol-interference can be exploited to benefit from oversampling.

Window decoding schedules are very attractive for message passing decoding of spatially coupled LDPC codes. They take advantage of the inherent convolutional code structure and allow continuous transmission with low decoding latency and complexity. In this paper we show that the decoding complexity can be further reduced if suitable message passing schedules are applied within the decoding window. An improvement based schedule is presented that easily adapts to different ensemble structures, window sizes, and channel parameters. Its combination with a serial (on-demand) schedule is also considered. Results from a computer search based schedule are shown for comparison.

Die Dresden Summer School 2012 gliedert sich in vier aufeinander folgende Sektionen. Diese bestehen aus Vorträgen, Diskussionen, Workshops, Kuratorengesprächen und Führungen. Die Kooperation der fünf renommierten Dresdner Kunst-und Kulturstätten bietet den TeilnehmerInnen ein vielfältiges inhaltliches Angebot und einen Ideen- und Erfahrungsaustausch in verschiedenen Fachbereichen. Die Sektionen der Dresden Summer School 2012: 1. Digitalisierung in Museen und Bibliotheken. Erfahrungen, Methoden, Strategien. 2. Akademische Forschung und universitäre Sammlungen im digitalen Zeitalter. 3. Virtuelle Inventarisierung – Potentiale der Provenienzforschung. 4. Kulturelle Bildung und Social Media.:EINLEITUNG S. 9 SEKTIONEN S. 15 Kulturelle Gedächtnisinstitutionen und ihre digitale Zukunft - Sächsische Landesbibliothek – Staats- und Universitätsbibliothek Dresden S. 17 Akademische Forschung und universitäre Sammlungen - Technische Universität Dresden S. 25 Datenbanken, Inventarisierung, Provenienzforschung - Staatliche Kunstsammlungen Dresden S. 31 Kulturelle Bildung und Social Media - Deutsches Hygiene-Museum Dresden / Militärhistorisches Museum der Bundeswehr S. 41 EXKURSIONEN S. 47 Nur Mut zum Prozess! Oder: Wie kann zeitgemäße, mediale Ausstellungsgestaltung gelingen? Exkursion in das Staatliche Museum für Archäologie Chemnitz S. 48 Exkursion ins Museum der deutschsprachigen Bewohner der böhmischen Länder in Ústí nad Labem (Aussig) S. 58 PRÄSENTATIONEN S. 63 Speicherchip der Vergangenheit S. 65 Der Maya-Countdown 21/12 S. 73 Ich sammle S. 81 Steuerung Alt Entfernen / Re-boot Science S. 87 BIOGRAPHIEN S. 95 Teilnehmer S. 96 Referenten S. 102 INSTITUTIONEN S. 112

Bereits seit einiger Zeit ist von Seiten kulturgutverwahrender Institutionen ein Aufbruch in Richtung der digitalen Welt zu konstatieren. Eine steigende Anzahl von Tagungen, Publikationen und kulturwissenschaftlichen Studien zu diesem Thema belegt dies.1 Doch welche Umbrüche in den Strukturen, im Denken und in den Strategien sind notwendig, um die digitale Zukunft erfolgreich zu beschreiten? (...)

Die zweite Sektion begann am 4. Oktober mit einem einführenden Vortrag von Klaus Mauersberger über die Entwicklung, die Bewahrung und die Spezifik der Sammlungen der TU Dresden. Mauersberger, langjähriger Mitarbeiter am Zentrum für Geschichte der Technikwissenschaften und seit 1993 Leiter der Kustodie der TU Dresden, gab einen Überblick über die Anfänge, die Aufgaben sowie den Umfang und die Diversität der Dresdner Universitätssammlungen. (...)