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IEEE International Conference on Communications (ICC)

作者： S. Bracciali R. Fantacci T. Pecorella L. Chisci M. A. V. Castro CNIT Unit Università di Firenze Florence Italy Department di Sistemi e Informatica Università di Firenze Florence Italy Dpt of Telecommunications and System Engineering Universitat Autònoma Barcelona Barcelona Spain

The paper studies the performance of the bandwidth request procedure for a proactive digital video broadcasting - return channel satellite (DVB- RCS) terminal in comparison with a reactive one. The proactive terminal uses an adaptive predictor to forecast the future input traffic flow along with a predictive bandwidth controller to generate bandwidth requests according to a receding horizon policy. On the other hand, the reactive terminal generates requests, at the end of each frame, depending on the current queue lengths [1] [2]. The simulated scenario involves adaptive coding and modulation (ACM) techniques and Quality of Service (QoS) management. Simulation experiments highlight the effectiveness of the proactive bandwidth control under different traffic load and channel conditions.

关键词： Digital video broadcasting Bandwidth Quality of service Satellite broadcasting Programmable control adaptive control Traffic control adaptive coding Modulation coding Quality management

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A Novel Technique for Input Vector Compression in System-on-Chip Testing

A Novel Technique for Input Vector Compression in System-on-...

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International Conference on Information Technology (ICIT)

作者： Satyendra N. Biswas Sunil R. Das Mansour H. Assaf Department of Electrical Engineering Technology Georgia Southern University Statesboro GA USA School of Information Technology and Engineering Faculty of Engineering University of Ottawa Ottawa ONT Canada Department of Computer and Information Science College of Arts and Sciences Troy University Montgomery AL USA University of Trinidad and Tobago Arima Trinidad and Tobago

A software based hybrid test vector compression technique for testing system-on-chip integrated circuits using an embedded processor core was previously discussed by the authors. In this approach, a software program is loaded into the on-chip processor memory along with the compressed test data sets. To minimize on-chip storage besides testing time, the test data volume is first reduced by compaction in a hybrid manner before downloading into the processor. The proposed method utilizes a set of adaptive coding techniques for realizing lossless compression. The compaction program need not be loaded into the embedded processor, as only the decompression of test data is required for the automatic test equipment. The developed scheme necessitates minimal hardware overhead, while the on-chip embedded processor can be reused for normal operation on completion of testing. As an extension of this prior work, this paper reports further results on studies of the problem based on the use of Limpel-Ziv-Walsh coding besides Burrows-Wheeler transformation and demonstrates the feasibility of the suggested methodology with simulation results on ISCAS 85 combinational and ISCAS 89 full-scan sequential benchmark circuits.

关键词： System-on-a-chip System testing Circuit testing Software testing Integrated circuit testing Compaction Embedded software Hybrid integrated circuits adaptive coding Automatic testing

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Link Adaptation with Retransmissions for Partial Channel State Information

Link Adaptation with Retransmissions for Partial Channel Sta...

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IEEE GLOBECOM 2008 - 2008 IEEE Global Telecommunications Conference

作者： Stephan Pfletschinger Monica Navarro Centre Tecnològic de Telecomunicacions de Catalunya (CTTC) Parc Mediterrani de la Tecnologia Barcelona Spain

We consider the performance of adaptive coding and modulation (ACM) over a fading channel for the case that the transmitter has only partial channel state information (CSI). We evaluate the degradation due to the partial CSI in terms of additionally required SNR by simulations and an analytical approximation. Then, we propose an ACM scheme with fast link-level retransmissions based on cyclic incremental redundancy and compare its performance to an equivalent scheme based on Chase combining. For both HARQ (hybrid automatic repeat request) schemes, we develop an analytical approximation for the throughput and the delay.

关键词： Channel state information adaptive coding Modulation coding Fading Transmitters Degradation Analytical models Automatic repeat request Throughput Delay

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System-level performance evaluation of winner system

System-level performance evaluation of winner system

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ITG Workshop on Smart Antennas

作者： Krystian Safjan Jakub Oszmianski Adrian Bohdanowicz Martin Dottling Nokia Siemens Networks Wroclaw Poland Nokia Siemens Networks Munich Germany

This paper investigates the performance of Beyond 3G system following the requirements defined in WINNER (phase I and II) Project and concentrates on two major topics. The first one is a novel frequency domain mutual-information based adaptive coding and modulation (MI-ACM), the second one is the impact of traffic modeling and scheduling on delay and spectral efficiency of such systems. Different MIMO schemes, including Alamouti and PARC utilizing Grid of Beams and SDMA, are examined on the system-level in terms of spectral efficiency and packet delays.

关键词： Traffic control Delay Modulation coding Bandwidth Signal to noise ratio adaptive coding Job shop scheduling Throughput Coherence Frequency domain analysis

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Cross-Layer and Path Priority Scheduling Based Real-Time Video Communications over Wireless Sensor Networks

Cross-Layer and Path Priority Scheduling Based Real-Time Vid...

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IEEE Conference on Vehicular Technology (VTC)

作者： Min Chen Victor C. M. Leung Shiwen Mao Ming Li Department ECE University of British Columbia Canada Department ECE Aubum University Auburn AL USA Department CS California State University Fresno CA USA

This paper addresses the problem of real-time video streaming over a bandwidth and energy constrained wireless sensor network (WSN). Considering the compressed video bit stream is extremely sensitive to transmission errors, and the constraints in bandwidth and energy in WSNs and delay in video delivery, we exploit the construction of an application-specific number of multiple disjoint paths to enlarge the aggregate bandwidth and facilitate load balancing and fast packet delivery. For efficient multi-path routing of real-time video frames, we propose a path priority scheduling algorithm to satisfy the delay constraint of video frames while balancing energy and bandwidth usage among all the available paths. In the case that the aggregate bandwidth is still not enough to satisfy the required coding rate, we further exploit a cross-layer technique for adaptive coding according to path status. The effectiveness of the proposed scheme is evaluated and demonstrated by simulations.

关键词： Wireless sensor networks Bandwidth Video compression Streaming media Delay Aggregates Load management Routing Scheduling algorithm adaptive coding

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An adaptive fast multiple reference frames selection algorithm for H.264/AVC

An adaptive fast multiple reference frames selection algorit...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Peng Wu Chuang-Bai Xiao College of Computer Science and Technology Beijing University of Technology Beijing China

To make full use of the temporal correlation of video sequences, H.264/AVC adopts multiple reference frames to enhance the coding quality. While the performance being improved, the complexity of computation has been increased linearly, too. In this paper, we study motion characteristic of video sequences and spatial correlation in video frames first, and then we propose an adaptive fast multiple reference frames selection algorithm. It can decrease the number of reference frames for motion compensation, and reduce the complexity of coding adaptively according to the features of video sequences. The results show that our algorithm achieves 45% coding time saving on average with unnoticeable quality loss.

关键词： Automatic voltage control Video sequences Motion compensation PSNR IEC standards ISO standards Motion estimation Educational institutions Computer science adaptive coding

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LDPC Coded Wireless Networks with adaptive Spectral Efficiency

LDPC Coded Wireless Networks with Adaptive Spectral Efficien...

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IEEE International Conference on Circuits and Systems for Communications (ICCSC)

作者： Zhiyong He Sebastien Roy Department of Electrical and Computer Engineering Laval University Quebec QUE Canada

Low-density parity-check (LDPC) codes offer a very powerful error correction technique which allows data transmission in wireless networks at rates near the channel capacity with arbitrarily low probability of error. In this paper, we design a class of linearly encodable LDPC codes with adaptive code rates, i.e. the code rate can be adapted according to channel conditions to maximize the total capacity. Since a unique mother parity check matrix is used to construct LDPC codes with several code rates, the great advantage of the proposed codes is that a single universal encoder (decoder) is adequate to encode (decode) multi-rate codes, which makes it possible to efficiently implement multi-rate LDPC codes in a subscriber station. The implementation results into field programmable gate array (FPGA) devices indicate that a universal layered encoder for LDPC codes with 9 code rates is capable of reaching a throughput above 1.2 Gigabit per second by using 138 exclusive- OR gates and a master clock of 100 MHz. By combining multilevel modulation with the designed multi-rate LDPC codes, a transmission scheme with adaptive spectral efficiency is proposed. The simulation results indicate that the schemes with a spectral efficiency of 1, 2, 3, 4, and 5 bits/symbol/Hz can achieve extremely reliable transmission in a Rayleigh fading channel at signal-to-noise ratios (SNR) per bit of 5, 6, 10, 14, and 16 dB, respectively.

关键词： Parity check codes Wireless networks adaptive systems Error correction codes Decoding Field programmable gate arrays Data communication Channel capacity adaptive coding Throughput

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Reduced-complexity Woven Serial Concatenated TCM for tactical OFDM communications

Reduced-complexity Woven Serial Concatenated TCM for tactica...

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MILCOM, Military Communications Conference

作者： Hugo M. Tullberg Department of Communication Systems Swedish Defence Research Agency Linkoping Sweden

Orthogonal frequency division multiplexing (OFDM) with adaptive coding and modulation (ACM) gives a communication system that can adapt to varying channel conditions and provide reliable communication at a wider range of signal to noise-ratios (SNRs). We investigate how the number of available transmission rates in the ACM scheme impacts communication performance and feedback requirements. To accommodate for the various rates in the ACM system we use serial concatenated trellis-coded modulation (SCTCM) consisting of a rate-compatible punctured convolutional (RCPC) code or a woven serial concatenated convolutional (WSCC) code, both with a rate-1 inner accumulate code and mapping to a Gray-labeled signal constellation. We show that significant reductions in complexity and corresponding savings in protocol overhead can be obtained without significant performance degradation. It is shown that an equal spacing of available rates over the expected range of SNRs is preferable to an uneven spacing.

关键词： Concatenated codes Modulation coding Convolutional codes Convolution adaptive coding OFDM modulation Feedback Signal mapping Constellation diagram Protocols

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Contour adaptive image coding

Contour adaptive image coding

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Xin Li Lane Department of Computer Science and Electrical Engineering West Virginia University Morgantown WV USA

ISBN: (纸本)0780388747

This paper presents a new image coding framework that separates singularities based on their topological dimension: point singularities (0D), line singularities (1D) and plane singularities (2D). Contours are smooth curves corresponding to line singularities and boundaries of plane singularities. We propose to directly code contour locations in the spatial domain and spatially adapt the bases to approximate various singularities conditioned on contour locations. The key to the success of our forward adaptive coding lies in the exploitation of contour geometry while achieving spatial adaptation. Preliminary experimental results are used to demonstrate the potential of our approach.

关键词： Image coding Cameras Layout Frequency Shape Object segmentation adaptive coding Geometry Wavelet coefficients Solid modeling

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Capacity analysis and system optimization for the reverse link of multi-beam satellite broadband systems exploiting adaptive coding and modulation

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INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING 2004年第4期22卷 425-448页

作者： Rinaldo, R De Gaudenzi, R European Space Agcy ESTEC TEC ETC NL-2200 AG Noordwijk Netherlands

This paper deals with the system capacity analysis and assessment of the potential advantages provided by the introduction of adaptive coding and Modulation (ACM) in the reverse link of multi-beam broadband satellite systems. ACM is intended to increase the system throughput for a given terminal EIRP power by optimizing the individual links physical layer to the current channel conditions. The physical layer adaptation will be driven by the inbound demodulator signal over noise plus interference ratio (SNIR) estimation. A general methodology for ACM physical layer optimization based on the system capacity maximization is also illustrated. A theoretical analysis of ACM systems capacity is performed for both time division multiple access (TDMA) and code division multiple access (CDMA) schemes. As the exact analytical capacity computation results to be very complex while Monte Carlo approach leads to very time consuming simulations, a simplified semi-analytic approach is devised. Numerical results showing the huge improvement in terms of capacity by the ACM adoption are obtained for both the semi-analytic and the Monte Carlo approaches in a realistic study case corresponding to a Ka-band multibeam satellite system. A good match between the two approaches is also demonstrated. Copyright (C) 2004 John Wiley Sons, Ltd.

关键词： system optimization Satellite systems Physical layer Code division multiple access reverse link broadband system adaptive coding system capacity time division multiple access multi-beam

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