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National Conference on Radio Science (NSRC)

作者： M.H. Ismail H.-A.M. Mourad Cairo University Giza EG Dept. of Electron. & Electr. Commun. Cairo Univ. Giza Egypt

adaptive coding techniques have been proposed in the literature as a method of increasing the throughput obtained by each user in wireless communication systems. Some of these schemes, along with adaptive modulation, have been adopted as part of the next generation mobile communications systems standards including GPRS and EDGE. These systems aim at providing users with high data rates reaching approximately 400 Kbps. In this paper, we present a novel adaptive coding technique for Rayleigh fading channels based on the use of Markov chains. A complete mathematical analysis of the system is presented and the performance of the system is compared, in terms of throughput, to other nonadaptive schemes pointing out its efficiency in obtaining the maximum throughput.

关键词： adaptive coding Throughput Fading Protection Wireless communication Mobile communication Mathematical analysis Radio transmitters adaptive systems Cities and towns

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GBS over WGS Using DVB-S and DVB-S2 (#1546)

GBS over WGS Using DVB-S and DVB-S2 (#1546)

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MILCOM, Military Communications Conference

作者： Bruce Bennett Daniel Hannan James Marshall Richard Gibbons DISA SMDC/ARSTRAT USA MITRE Corporation USA

This paper determines the link performance of Global Broadcast Service (GBS) when it is transitioned to Wideband Global SATCOM (WGS) satellites. Current and future (smaller) GBS terminals as well as current Digital Video Broadcast-Satellite (DVB-S) and future (DVB-S2) Modems are considered. DVB-S2 provides a large increase in capability in terms of modulations and forward error correcting coding rates. In addition, DVB-S2 allows for different modulations and coding to different terminals using variable coding and modulation (different streams are coded with different, fixed parameters within the DVB-S2 physical layer frame). Further DVB-S2 allows adaptive coding and modulation whereby each frame is coded with its own set of parameters (which are dynamically modified according to reception conditions). The WGS performance will be based on a System Utilization Plan (SUP) including a frequency plan and beam configuration applied to the first WGS satellite placed in orbit at 175E. The WGS SUP includes a case where two uplink carriers in a single WGS 125 MHz channel are fanned-out to two Ka-band downlink beams where the downlink carriers share the same channel. Cases where the single GBS downlink carrier shares the 125 MHz channel with non-GBS traffic are also considered. A Theater Injection Point (TIP) uplink into a narrow beam with the downlink in a wide bean is also defined. Several propagation margins are considered to allow results to be applied to different receive terminal locations.

关键词： Digital video broadcasting Satellite broadcasting Modulation coding Downlink Wideband Modems Error correction Streaming media Physical layer adaptive coding

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The adaptive Code Kitchen: Flexible Tools for Dynamic Application Composition

The Adaptive Code Kitchen: Flexible Tools for Dynamic Applic...

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International Symposium on Parallel and Distributed Processing (IPDPS)

作者： Pilsung Kang Mike Heffner Joy Mukherjee Naren Ramakrishnan Srinidhi Varadarajan Cal Ribbens Danesh K. Tafti Department of Computer Science Virginia Polytechnic Institute and State University Blacksburg VA USA Department of Mechanical Engineering Virginia Polytechnic Institute and State University Blacksburg VA USA

Driven by the increasing componentization of scientific codes, the deployment of high-end system infrastructures such as the grid, and the desire to support high level problem solving primitives, application composition systems have become prevalent in computational science practice. We present the adaptive code kitchen which, as the name connotes, is a loose collection of capabilities to help realize complex adaptive composition scenarios. These include function interception, continuation modification, dynamic process checkpointing and rollback, and runtime recommendation. Using these broad primitives, a computational scientist can specify many 'recipes' of adaptivity as complete control systems around native object codes. Runtime systems support then enables loading and linking of native code components, monitoring of performance indicators, consulting a recommender system for algorithmic decisions, and dynamically updating application components in response to the recommendations. We present the architecture of the adaptive code kitchen and the key enabling technologies with brief mention of the applications that will be investigated henceforth during the course of the project.

关键词： adaptive coding Problem-solving Grid computing Checkpointing Runtime Control systems Joining processes Monitoring Recommender systems Heuristic algorithms

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Triple Play Services Delivery over a DVB-S2 Satellite Network

Triple Play Services Delivery over a DVB-S2 Satellite Networ...

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Mobile and Wireless Communications Summit

作者： Georgios Gardikis Nikolaos Zotos Anastasios Kourtis National Center for Scientific Research Demokritos Institute of Informatics and Telecommunications Athens Greece

Digital satellite broadcasting, primarily targeted to unidirectional services, soon expanded to the interactive domain, utilising uplink technologies such as DVB-RCS. In this context, due to their wide and uniform coverage, satellites can provide an ideal medium for the provision of triple play services (voice, video and data) to remote areas not covered by terrestrial infrastructures. This paper discusses and demonstrates the delivery of triple play services over a fully functional platform utilising the second-generation satellite broadcasting technology (DVB-S2) for the downlink combined with DVB-RCS for the uplink.

关键词： Digital video broadcasting Satellite broadcasting Modulation coding Isolation technology TV adaptive coding Satellite communication Parity check codes Artificial satellites Telephony

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Novel IP Encapsulation and Burst Format Optimization for the Return Link of Interactive Satellite Systems

Novel IP Encapsulation and Burst Format Optimization for the...

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IEEE GLOBECOM 2007 - IEEE Global Telecommunications Conference

作者： R. Rinaldo T. Flo B. Rislow Ø. Weum H. P. Lexow J. Tousch ESA-ESTEC European Space Agency Noordwijk Netherlands Thrane and Thrane Billingstad Norway STM Norway Lysaker Norway Turbo Concept SAS Plouzane France

A number of novel physical layer techniques, and in particular adaptive coding and modulation (ACM) combined with high order modulations, have shown the potential to significantly improve throughput of current return link (RL) broadband access satellite systems. However, their introduction shall be complemented by novel concepts at MAC and network layer, which aim at increasing flexibility and maximizing actual achieved system efficiency, In this paper a novel frame and burst format is proposed, capable of ensuring high overall efficiency combined with radio resource management (RRM) simplicity. A comprehensive cross-layer optimization is carried out through simulation and numerical assessment in order to optimize burst lengths taking into account physical layer performances and network traffic profiles. Moreover, a novel encapsulation protocol (generic stream encapsulation-GSE) is considered to further improve IP transport efficiency.

关键词： Encapsulation Satellite broadcasting Physical layer Modulation coding adaptive coding Throughput Resource management Numerical simulation Telecommunication traffic Traffic control

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Low-rate and flexible image coding with redundant representations

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IEEE TRANSACTIONS ON IMAGE PROCESSING 2006年第3期15卷 726-739页

作者： Ventura, RMFI Vandergheynst, P Frossard, P Ecole Polytech Fed Lausanne Signal Proc Inst Swiss Fed Inst Technol CH-1015 Lausanne Switzerland

New breakthroughs in image coding possibly lie in signal decomposition through nonseparable basis functions that can efficiently capture edge characteristics, present in natural images. The work proposed in this paper provides an adaptive way of representing images as a sum of two-dimensional features. It presents a low bit-rate image coding method based on a matching pursuit (NIP) expansion, over a dictionary built on anisotropic refinement and rotation of contour-like atoms. This method is shown to provide, at low bit rates, results comparable to the state of the art in image compression, represented here by JPEG2000 and SPIHT, with generally a better visual quality in the NIP scheme. The coding artifacts are less annoying than the ringing introduced by wavelets at very low bit rate, due to the smoothing performed by the basis functions used in the NIP algorithm. In addition to good compression performances at low bit rates, the new coder has the advantage of producing highly flexible streams. They can easily be decoded at any spatial resolution, different from the original image, and the bitstream can be truncated at any point to match diverse band-width requirements. The spatial adaptivity is shown to be more flexible and less complex than transcoding operations generally applied to state of the art codec bitstreams. Due to both its ability for capturing the most important parts of multidimensional signals, and a flexible stream structure, the image coder proposed in this paper represents an interesting solution for low to medium rate image coding in visual communication applications.

关键词： adaptive coding image compression multidimensional transform nonlinear representation redundant expansions

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Multiuser distortion management of layered video over resource limited downlink multicode-CDMA

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2006年第11期5卷 3056-3067页

作者： Han, Zhu Su, Guan-Ming Kwasinski, Andres Wu, Min Liu, K. J. Ray Boise State Univ Dept Elect & Comp Engn Boise ID 83725 USA ESS Technol Fremont CA 94538 USA Univ Maryland Dept Elect & Comp Engn College Pk MD 20742 USA Univ Maryland Syst Res Inst College Pk MD 20742 USA

Transmitting multiple real-time encoded videos to multiple users over wireless cellular networks is a key driving force for developing broadband technology. We propose a new framework to transmit multiple users' video programs encoded by MPEG-4 FGS codec over downlink multicode CDMA networks in real time. The proposed framework jointly manages the rate adaptation of source and channel coding, CDMA code allocation, and power control. Subject to the limited system resources, such as the number of pseudo-random codes and the maximal power for CDMA transmission, we develop an adaptive scheme of distortion management to ensure baseline video quality for each user and further reduce the overall distortion received by all users. To efficiently utilize system resources, the proposed scheme maintains a balanced ratio between the power and code usages. We also investigate three special scenarios where demand, power, or code is limited, respectively. Compared with existing methods in the literature, the proposed algorithm can reduce the overall system's distortion by 14% to 26%. In the demand-limited case and the code-limited but power-unlimited case, the proposed scheme achieves the optimal solutions. In the power-limited but code-unlimited case, the proposed scheme has a performance very close to a performance upper bound.

关键词： resource management multimedia communication code division multiaccess land mobile radio cellular systems adaptive coding

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Stochastic automata-based estimators for adaptively compressing files with nonstationary distributions

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IEEE TRANSACTIONS ON SYSTEMS MAN AND CYBERNETICS PART B-CYBERNETICS 2006年第5期36卷 1196-1200页

作者： Rueda, Luis Oommen, B. John Univ Concepcion Dept Comp Sci Concepcion 4030000 Chile Carleton Univ Sch Comp Sci Ottawa ON K1S 5B6 Canada

This correspondence shows that learning automata techniques, which have been useful in developing weak estimators, can be applied to data compression applications in which the data distributions are nonstationary. The adaptive coding scheme utilizes stochastic learning-based weak estimation techniques to adaptively update the probabilities of the source symbols, and this is done without resorting to either maximum likelihood, Bayesian, or sliding-window methods. The authors have incorporated the estimator in the adaptive Fano coding scheme and in an adaptive entropy-based scheme that "resembles" the well-known arithmetic coding. The empirical results obtained for both of these adaptive methods are obtained on real-life files that possess a fair degree of non-stationarity. From these results, it can be seen that the proposed schemes compress nearly 10% more than their respective adaptive methods that use maximum-likelihood estimator-based estimates.

关键词： adaptive coding Fano coding nonstationary sources online data compression weak estimators

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Optimal unequal error protection with user cooperation for transmission of embedded source-coded images

Optimal unequal error protection with user cooperation for t...

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IEEE International Conference on Image Processing (ICIP 2006)

作者： Kwasinski, Andres Liu, K. J. Ray Univ Maryland Dept Elect & Comp Engn College Pk MD 20742 USA

ISBN: (纸本)9781424404810

This paper studies the transmission of images encoded using an embedded source encoder over a wireless network allowing user cooperation. A dynamic programming algorithm is applied to optimally allocate to each source coded packet error protection in the form of a choice of channel code and a decision on the use of cooperation. The results show that for degraded source-destination channels, the use of user cooperation on all source coded packets significantly improves the reconstructed quality. As the source-destination channel improves the optimal policy becomes a hybrid that uses user cooperation only for the most important source packets. When the source destination channel is sufficiently good, all source packets are sent without cooperation. Thus, a test is presented to estimate the channels states when cooperation is first used.

关键词： image communication cooperative systems adaptive coding channel coding source coding

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Layering as optimization decomposition: Current status and open issues

Layering as optimization decomposition: Current status and o...

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40th Annual Conference on Information Sciences and Systems (CISS)

作者： Chiang, Mung Low, Steven H. Calderbank, A. Robert Doyle, John C. Princeton Univ Dept Elect Engn Princeton NJ 08544 USA CALTECH Dept Comp Sci & Elect Engn Pasadena CA 91125 USA Princeton Univ Dept Elect Engn & Math Princeton NJ 08544 USA CALTECH Control & Dynam Syst Dept Pasadena CA 91125 USA

ISBN: (纸本)1424403499

Net work protocols in layered architectures have historically been obtained on an ad-hoe basis, and much or the recent cross-layer designs are conducted through piecemeal approaches. Network protocols may instead be holistically analyzed and systematically designed as distributed solutions to some global optimization problems in the form of generalized Network Utility Maximization (NUM), providing insight on what they optimize and structures of the network protocol stack. This paper presents a short survey of the recent efforts towards a systematic understanding or "layering" as "optimization decomposition", where the overall communication network is modeled by a generalized NUM problem, each layer corresponds to a decomposed subproblem, and the interfaces among layers are quantified as functions of the optimization variables coordinating the subproblems. Furthermore, there are many alternative decompositions, each leading to a different layering architecture. Industry adoption of this unifying framework has also started. Here we summarize the current status of horizontal decomposition into distributed computation and vertical decomposition into functional modules such as congestion control, routing, scheduling, random access, power control, and coding. Key messages and methodologies arising out of many recent work are listed. Then we present a list of challenging open issues in this area and the initial progress made on some of them.

关键词： adaptive coding cross-layer design congestion control distributed algorithm Lagrange duality MAC network utility maximization optimization power control reverse engineering routing TCP/IP scheduling stochastic control wireless ad hoc networks

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