| Zeitplan | Themen | (Letzte Aktualisierung: ) |
Das Seminar soll begleitend zu den Vorlesungen des Lehrstuhls die Möglichkeit bieten, selbstständig ein aktuelles Forschungsthema oder Spezialthema, das in den Vorlesungen nicht behandelt wird, darzustellen. Gleichzeitig soll die Ausarbeitung eines Fachvortrages und dessen Präsentation geübt werden. Der Ablauf gliedert sich wie folgt:
Eine gute Zusammenfassung über das erfolgreiche Gestalten und Halten eines Vortrags findet ihr auf den Seiten der Universität von Canberra (Giving an Oral Presentation). Beschränkt euch bei der Ausarbeitung auf 10 bis 12 Folien und denkt daran, Handouts vorzubereiten. Letztere können am Lehrstuhl vervielfältigt werden. Laptop und Beamer werden für den Vortrag von uns zur Verfügung gestellt.
Die Ausarbeitung sollte sich an dem Aufbau einer wissenschaftlichen Veröffentlichung orientieren und ist zum Ende der Vorlesungszeit abzugeben. Neben dem eigentlichen Inhalt gehören hierzu eine kurze Zusammenfassung, eine grobe Einführung in die Thematik mit klarer Herausstellung des Problems und ein Literaturverzeichnis. Der Umfang der Ausarbeitung sollte je nach Bedarf 10 bis 15 Seiten betragen. Wünschenswert ist die Ausarbeitung in Englisch mit Latex. Für die Benotung sind neben der Ausarbeitung auch Vortrag und Diskussionsführung relevant.
Falls sich für die jeweiligen Termine kein Referent findet, findet an diesen Terminen kein Seminar statt. Im umgekehrten Fall, d.h. falls sich mehr Referenten als Termine finden, wird die Liste ggf. um zusätzliche Termine erweitert. Schaut daher bitte regelmäßig nach Aktualisierungen.
| Datum | Referent | Thema | Tutor |
| 16.10.08 | Bastian Ristau | Eingangskolloquium | |
| 30.10.08 | |||
| 13.11.08 | |||
| 27.11.08 | Kevin Erler | Video Coding | Eckhard Ohlmer |
| Benedikt Nöthen | Compilertechniken für VLIW DSPs | Xiaoyan Jia | |
| 11.12.08 | Jörg Hofrichter | Cooperative Relaying | Peter Rost |
| Daniel Bertko | Static Power and IC Design | Markus Winter | |
| 08.01.09 | |||
| 22.01.09 | Matthias Jüttner | Multiuser MIMO-OFDM | Vincent Kotzsch |
| 05.02.09 | |||
Ort: BAR 213/H, Zeit: 3. DS
Rot hinterlegte Themen sind bereits vergeben und sollen lediglich der Information / Vorbereitung der jeweils nicht referierenden Teilnehmer dienen.
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Thema Tutor |
Literatur Inhalt |
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Static Power and IC Design Markus Winter |
Nam Sung Kim, Todd Austin, David Blaauw, Trevor Mudge, Krisztian Flautner, Jie S.
Hu, Mary Jane Irwin, Mahmut Kandemir, Vijaykrishnan Narayanan, "Leakage Current:
Moore's Law Meets Static Power," Computer, vol. 36, no. 12, pp. 68-75, December,
2003. Inhalt: Off-state leakage is static power, current that leaks through transistors even when they are turned off. The other source of power dissipation in today's microprocessors, dynamic power, arises from the repeated capacitance charge and discharge on the output of the hundreds of millions of gates in today's chips. Until recently, only dynamic power has been a significant source of power consumption, and Moore's law helped control it. Microprocessor design has traditionally focused on dynamic power consumption as a limiting factor in system integration. But as feature sizes shrink below 0.1 micron, static power is posing new low-power design challenges. This paper describes mathematically the correlation between geometry and static current and its implications on future chip design. |
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Design Space Exploration Bastian Ristau |
Kunzli, S.; Thiele, L.; Zitzler, E., "Modular design space exploration framework
for embedded systems," Computers and Digital Techniques, IEE Proceedings - , vol.152,
no.2, pp. 183-192, Mar 2005 Inhalt: Design space exploration is introduced as one of the major tasks in embedded system design. After reviewing existing exploration methods at various layers of abstraction, a generic approach is described based on multi-objective decision making, black-box optimisation and randomised search strategies. The interface between problem-specific and generic parts of the exploration framework is made explicit by defining an interface called PISA. This specification and implementation interface, and the availability of a wide range of randomised multi-objective search methods, makes the proposed framework accessible to a wide range of exploration problems. It resolves the problem that existing optimisation methods cannot be coupled easily to the problem-specific part of a design exploration tool. |
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Iterative equalization and decoding Andre Fonseca dos Santos |
Tuchler, M.; Koetter, R.; Singer, A.C., "Turbo equalization: principles and new
results," Communications, IEEE Transactions on , vol.50, no.5, pp.754-767, May 2002 Inhalt: Capitalizing on the tremendous performance gains of turbo codes and the turbo decoding algorithm, turbo equalization is an iterative equalization and decoding technique that can achieve equally impressive performance gains for communication systems that send digital data over channels that require equalization, i.e. those which suffer from intersymbol interference (ISI). In this paper, a good overview about the turbo equalization approach to coded data transmission over ISI channels, with an emphasis on the basic ideas and some of the practical details. The original system introduced by Douillard, et al., can be viewed as an extension of the turbo decoding algorithm by considering the effect of the ISI channel as another form of error protection, i.e. as a rate-1 convolutional code. This paper is a good introduction to the topic and gives some foundations that can later on be applied to other system like: MIMO Turbo Equalization, Turbo Equalization with Turbo Decoding, iterative channel estimation and equalization and other interesting topics. |
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Algorithm Mapping Marcel Bimberg |
Novo, D.; Moffat, W.; Derudder, V.; Bougard, B., "Mapping a multiple antenna SDM-OFDM
receiver on the ADRES coarse-grained reconfigurable processor," Signal Processing
Systems Design and Implementation, 2005. IEEE Workshop on , vol., no., pp. 473-478,
2-4 Nov. 2005 Inhalt: The increasing demand for multimodal wireless communication is driving designers towards software defined radio. Therefore, new high performance reconfigurable platforms for baseband digital signal processing are required. Coarse Grain Reconfigurable Arrays (CGRAs) are one choice that provide the necessary flexibility and performance for the algorithms. ADRES is a CGRA that combines a VLIW processor with a reconfigurable coarse-grain array. In this paper, the mapping of the Space Division Multiplexing receiver on ADRES is analyzed. |
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UWB Receivers Stefan Krone |
Ranjan, M.; Larson, L. E., "Distortion Analysis of Ultra-Wideband OFDM Receiver
Front-Ends," Microwave Theory and Techniques, IEEE Transactions on , vol.54, no.12,
pp.4422-4431, Dec. 2006 Inhalt: This paper presents a comprehensive analysis of the effect of nonlinearities in ultra-wideband orthogonal frequency-division multiplexing receivers. The statistical properties of a quadrature phase-shift keying baseband signal are utilized to derive closed-form expressions for the power spectral density of cross-modulation, intermodulation, and harmonic distortion products of modulated signals, arising from second- and third-order nonlinearities in the receiver. Both narrowband and wideband jammers are considered. The derived expressions are then used to predict the effect of these nonidealites on the link budget of the system. |
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Video Coding Eckhard Ohlmer |
Schwarz, H.; Marpe, D.; Wiegand, T., "Overview of the Scalable Video Coding Extension
of the H.264/AVC Standard," Circuits and Systems for Video Technology, IEEE Transactions
on , vol.17, no.9, pp.1103-1120, Sept. 2007 Inhalt: With the introduction of the H.264/AVC video coding standard, significant improvements have recently been demonstrated in video compression capability. The Joint Video Team of the ITU-T VCEG and the ISO/IEC MPEG has now also standardized a Scalable Video Coding (SVC) extension of the H.264/AVC standard. SVC enables the transmission and decoding of partial bit streams to provide video services with lower temporal or spatial resolutions or reduced fidelity while retaining a reconstruction quality that is high relative to the rate of the partial bit streams. Hence, SVC provides functionalities such as graceful degradation in lossy transmission environments as well as bit rate, format, and power adaptation. These functionalities provide enhancements to transmission and storage applications. SVC has achieved significant improvements in coding efficiency with an increased degree of supported scalability relative to the scalable profiles of prior video coding standards. This paper provides an overview of the basic concepts for extending H.264/AVC towards SVC. Moreover, the basic tools for providing temporal, spatial, and quality scalability are described in detail and experimentally analyzed regarding their efficiency and complexity. |
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Implementation of MIMO OFDM Systems Mohammad Ali Shah |
van Zelst, A.; Schenk, T.C.W., "Implementation of a MIMO OFDM-based wireless LAN
system," Signal Processing, IEEE Transactions on [see also Acoustics, Speech, and
Signal Processing, IEEE Transactions on] , vol.52, no.2, pp. 483-494, Feb. 2004 Inhalt: The combination of multiple-input multiple-output (MIMO) signal processing with orthogonal frequency division multiplexing (OFDM) is regarded as a promising solution for enhancing the data rates of next-generation wireless communication systems operating in frequency-selective fading environments. To realize this extension of OFDM with MIMO, a number of changes are required in the baseband signal processing. An overview is given of the necessary changes, including time and frequency synchronization, channel estimation, synchronization tracking, and MIMO detection. As a test case, the OFDM-based wireless local area network (WLAN) standard IEEE 802.11a is considered, but the results are applicable more generally. The complete MIMO OFDM processing is implemented in a system with three transmit and three receive antennas, and its performance is evaluated with both simulations and experimental test results. Results from measurements with this MIMO OFDM system in a typical office environment show, on average, a doubling of the system throughput, compared with a single antenna OFDM system. An average expected tripling of the throughput was most likely not achieved due to coupling between the transmitter and receiver branches. |
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Compilertechniken für VLIW DSPs Xiaoyan Jia |
Rainer Leupers, "Compilertechniken für VLIW DSPs", 2005 Inhalt: Für Hochleistungsanwendungen der digitalen Signalverarbeitung werden zunehmendVLIW-Prozessorarchitekturen eingesetzt. Zur effektiven Programmierung von VLIW DSPs werden leistungsfahige C-Compiler benötigt. In diesem Beitrag zeigen wir einige Schwachstellen derzeitiger Compiler für VLIW DSPs auf und stellen hierfür neue Codeoptimierungsverfahren vor. Diese beziehen sich auf die Ausnutzung von SIMD-Befehlen und conditional instructions, sowie effizientes Scheduling und Funktions-Inlining. Experimentelle Ergebnisse für einen bekannten VLIW DSP, den Texas Instruments C6201, zeigen den praktischen Nutzen. Des weiteren werden auch Frontend-Aspekte und maschinenunabhängige Codeoptimierungen kurz behandelt. |
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Channel Estimation in OFDM Systems Zhijun Rong |
Coleri, S.; Ergen, M.; Puri, A.; Bahai A;, "A Study of Channel Estimation in OFDM
Systems", Proceedings of the IEEE, VTC 2002-Fall, vol. 2, pp. 894-898, Sept. 2002 Inhalt: The channel estimation techniques for OFDM systems based on pilot arrangement are investigated. The channel estimation based on comb type pilot arrangement is studied through different algorithms for both estimating channel at pilot frequencies and interpolating the channel. The estimation of channel at pilot frequencies is based on LS and LMS while the channel interpolation is done using linear interpolation, second order interpolation, low-pass interpolation, spline cubic interpolation, and time domain interpolation. Furthermore, the channel estimation based on block type pilot arrangement is performed by sending pilots at every sub-channel and using this estimation for a specific number of following symbols. Also a decision feedback equalizer is implemented for all sub-channels followed by periodic block-type pilots. The performances of all schemes are compared by measuring bit error rate with different modulation schemes and channel models. |
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Design of embedded systems Oliver Arnold |
"An Interrupt Controller for FPGA-based Multiprocessors", Tumeo, A.; Branca, M.;
Camerini, L.; Monchiero, M.; Palermo, G.; Ferrandi, F.; Sciuto, D.; Embedded Computer
Systems: Architectures, Modeling and Simulation, 2007. IC-SAMOS 2007. International
Conference on, 16-19 July 2007 Page(s):82 - 87 Inhalt: This paper presents the architecture of an Interrupt Controller for a FPGA-based multiprocessor composed of standard off-of-the-shelf softcores. The main feature of this device is to distribute multiple interrupts across the cores of a multiprocessor. In addition, the architecture supports several advanced features like booking, broadcasting and inter-processor interrupt. On the top of this hardware layer, we provide a software library to effectively exploit this mechanism. |
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SoC Energy Management Steffen Kunze |
Krisztian Flautner, David Flynn, Mark Rives, "A Combined Hardware-Software Approach
for Low-Power SoCs: Applying Adaptive Voltage Scaling and Intelligent Energy Management
Software," DesignCon 2003 Inhalt: Increased functionality and performance demands are challenging System-on-Chip (SoC) designers to seek better methods for optimizing available battery power in portable applications. Key areas of exploration include dynamic voltage scaling and improved software algorithms for the control of power modes. Dynamic voltage scaling can be improved by adaptively monitoring hardware performance to minimize the applied supply voltage for any given clock frequency. While adaptive voltage scaling optimizes power use based on temporal environmental conditions, Intelligent Energy Management (IEM) algorithms optimize power consumption based on the dynamic workload of the processor. IEM software and hardware monitor the execution and communication characteristics of workloads and predictively set the performance of the processor to the level that minimizes energy use, while still meeting application deadlines. The combined use of adaptive voltage scaling and IEM provides the optimum trade-off between performance and battery life for portable devices. |
|
Multiuser MIMO-OFDM Vincent Kotzsch |
Ming Jiang; Hanzo, L., "Multiuser MIMO-OFDM for Next-Generation Wireless Systems,"
Proceedings of the IEEE , vol.95, no.7, pp.1430-1469, July 2007 Inhalt: This overview portrays the evolution of orthogonal frequency division multiplexing (OFDM) research. The amelioration of powerful multicarrier OFDM arrangements with multiple-input multiple-output (MIMO) systems has numerous benefits, which are detailed in this treatise. We continue by highlighting the limitations of conventional detection and channel estimation techniques designed for multiuser MIMO OFDM systems in the so-called rank-deficient scenarios, where the number of users supported or the number of transmit antennas employed exceeds the number of receiver antennas. This is often encountered in practice, unless we limit the number of users granted access in the base station's or radio port's coverage area. Following a historical perspective on the associated design problems and their state-of-the-art solutions, the second half of this treatise details a range of classic multiuser detectors (MUDs) designed for MIMO-OFDM systems and characterizes their achievable performance. A further section aims for identifying novel cutting-edge genetic algorithm (GA)-aided detector solutions, which have found numerous applications in wireless communications in recent years. In an effort to stimulate the cross pollination of ideas across the machine learning, optimization, signal processing, and wireless communications research communities, we will review the broadly applicable principles of various GA-assisted optimization techniques, which were recently proposed also for employment in multiuser MIMO OFDM. In order to stimulate new research, we demonstrate that the family of GA-aided MUDs is capable of achieving a near-optimum performance at the cost of a significantly lower computational complexity than that imposed by their optimum maximum-likelihood (ML) MUD aided counterparts. The paper is concluded by outlining a range of future research options that may find their way into next-generation wireless systems. |
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Beamforming Albrecht Fehske |
Schubert, M.; Boche, H., "Solution of the multiuser downlink beamforming problem
with individual SINR constraints," Vehicular Technology, IEEE Transactions on ,
vol.53, no.1, pp. 18-28, Jan. 2004 Inhalt: The paper addresses the problem of joint downlink beamforming in a power-controlled network, where independent data streams are to be transmitted from a multiantenna base station to several decentralized single-antenna terminals. The total transmit power is limited and channel information (possibly statistical) is available at the transmitter. The design goal: jointly adjust the beamformers and transmission powers according to individual SINR requirements. In this context, there are two closely related optimization problems. P1: maximize the jointly achievable SINR margin under a total power constraint. P2: minimize the total transmission power while satisfying a set of SINR constraints. In this paper, both problems are solved within a unified analytical framework. Problem P1 is solved by minimizing the maximal eigenvalue of an extended crosstalk matrix. The solution provides a necessary and sufficient condition for the feasibility of the SINR requirements. Problem P2 is a variation of problem P1. An important step in our analysis is to show that the global optimum of the downlink beamforming problem is equivalently obtained from solving a dual uplink problem, which has an easier-to-handle analytical structure. Then, the authors make use of the special structure of the extended crosstalk matrix to develop a rapidly converging iterative algorithm. The optimality and global convergence of the algorithm is proven and stopping criteria are given. |
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MUD in CDMA by means of SVM Fred Richter |
Xiaohong Gong; Kuh, A., "Support Vector Machine for Multiuser Detection in CDMA
Communications," Conference Record of the Thirty-Third Asilomar Conference on Signals,
Systems, and Computers, 1999, Vol. 1, pp 680 - 684, Oct. 1999 Inhalt: In this paper, Support Vector Machines (SVM) or optimal margin classifiers to multiuser detection problems are applied. SVM are well suited for multiuser detection problems as they are based on principles of statistical learning theory where the goal is to construct a maximum margin classifier. It is shown that a linear SVM converges to the MMSE receiver in the noiseless case. The SVM are also modified to construct nonlinear receivers by using kernel functions and they approximate optimal nonlinear multiuser detection receivers. Using the Sequential Minimization Optimization (SMO) algorithm, SVM are implemented as receivers in CDMA systems and compared with traditional and adaptive receivers. The simulation performance of SVM compare favorably to these receivers. |