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IEEE Globecom Workshops

作者： Istvan Frigyes Laszlo Csurgai-Horvath Budapest University슠of슠Technology슠and슠Economics Budapest Hungary

In recent years mm-wave point-to-point radios appeared among wireless equipment. The large available bandwidth in principle up to 10 GHz - the sparse utilization of the frequency band and efficient spatial filtering make them very advantageous for the backhaul of cellular networks. Present day equipment transmit 1 Gbit/sec over paths of several, about 1 to 3 km-s. The aim of this paper is to briefly present features and applications of these equipments and to discuss development possibilities. Concerning the increase of hop length the already used technique of rate adaptation is analyzed and two diversity techniques are presented. About increase of transmission rate up to 10 Gbit/sec it is shown that simply rescaling the methods used in actual systems is virtually non-viable and more sophisticated methods are needed. Two techniques are proposed and investigated, (i) Spatial demultiplexing of channels is presented; conditions of application are shown, (ii) Possibilities offered by adaptive coding are investigated.

关键词： Bandwidth Bit rate Frequency Land mobile radio cellular systems Urban areas Optical fiber devices Next generation networking Filtering Demultiplexing adaptive coding

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A Fast Algorithm for adaptive Prefix coding

A Fast Algorithm for Adaptive Prefix Coding

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IEEE International Symposium on Information Theory

作者： Marek Karpinski Yakov Nekrich Department of Computer Science University of Bonn Germany

ISBN: (纸本)142440505X

In this paper we present a new algorithm for adaptive prefix coding. Our algorithm encodes a text S of m symbols in O(m) time, i.e., in O(1) time per symbol. The length of the encoded string is bounded above by (H + 1)m + O(nlog 2 m) bits where n is the alphabet size and H is the entropy. This is the first algorithm that works in O(m) time and achieves an almost optimal bound on the encoding length in the worst case. Besides that our algorithm does not depend on the explicit tree traversal

关键词： Huffman coding Decoding Computer science Entropy Encoding adaptive coding Upper bound Data compression Transform coding Table lookup

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Toward a unified framework for modeling and analysis of diversity in joint source-channel coding

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IEEE TRANSACTIONS ON COMMUNICATIONS 2008年第1期56卷 90-101页

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

The study of Joint Source-Channel coding (JSCC) systems faces one major challenge in obtaining an analytical expression for the function that links end-to-end distortion with channel signal-to-noise ratio, the D-SNR curve. In this paper, for certain multimedia systems using practical source and channel codes in a JSCC bit rate allocation design, the D-SNR curve is shown to be well approximated by a set of carefully selected points where the relative contribution of channel errors to end-to-end distortion is small. This approach has the potential advantage that it could be applied to represent performance of many practical systems using JSCC bit rate allocation for which it is shown that the D-SNR function is approximately linear in log-log scales. A unified framework for the modeling, analysis and performance measurement of these systems is proposed by considering a view of diversity more general than its usual interpretation. This view extends that of diversity to include redundant information so coding and diversity gain are still used to characterize performance. Furthermore, the proposed approach is applied to study issues arising from using practical source and channel codes, including the effects on performance of channel codes of different strength or source codes with different compression efficiency.

关键词： adaptive coding source coding channel coding

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adaptive Modulation and coding Schemes for a Space-time Coded System with Transmit Antenna Selection

Adaptive Modulation and Coding Schemes for a Space-time Code...

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IEEE Region 10 International Conference TENCON

作者： YingRao Wei M.Z. Wang Department of Electronic and Information Engineering Hong Kong Polytechnic University Hong Kong China

In this paper, we propose two adaptive schemes where either the modulation mode or the space-time block code (STBC) pattern is changed for a space-time coded system with transmit antenna selection. Simulation results show that the improvements in terms of capacity, data throughput and BER can be obtained over the nonadaptive schemes

关键词： Modulation coding adaptive arrays Transmitting antennas MIMO Block codes Receiving antennas Bit error rate Maximum likelihood decoding Transmitters adaptive coding

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Performance analysis of an efficient packet-based IEEE 802.16 MAC supporting adaptive modulation and coding

Performance analysis of an efficient packet-based IEEE 802.1...

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International Symposium on Computer Networks, ISCN

作者： M. Settembre M. Puleri S. Garritano P. Testa R. Albanese M. Mancini V. Lo Curto Ericsson Laboratory Italy Rome Italy CoRiTeL Rome Italy

The challenge for broadband fixed wireless access (BFWA) systems, which represent an attractive solution for broadband access in the last mile and for wireless backhauling applications in the "middle mile", lies in providing high data rates and quality of service (QoS). Such requirements mainly derive from the need to provide new bandwidth consuming multimedia services and applications, efficient handling of IP traffic, effective use of the limited radio spectrum and a greater backhaul capacity to support the increased number of users per cell site. IEEE 802.16 family of standards and its associated consortium WiMAX are gaining more and more interest in the telecommunication areas as broadband fixed wireless access solution with possible extension in nomadic and mobile area. Its main leverages are an efficient handling of IP traffic, the support of channel adaptivity and advanced QoS management. This paper aims at defining a new packet-based scheduling strategy for an IEEE 802.16 system supporting variable length MAC protocol data units (PDUs) and adaptive coding and modulation while fulfilling QoS requirements. A performance analysis of the proposed scheduler is presented and discussed in terms of packet transfer delay, MAC overhead and average throughput

关键词： Performance analysis Modulation coding Quality of service Telecommunication traffic Bandwidth Telecommunication standards WiMAX Media Access Protocol Access protocols adaptive coding

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adaptive-rate nonbinary LDPC coding for frequency-hop communications

Adaptive-rate nonbinary LDPC coding for frequency-hop commun...

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MILCOM, Military Communications Conference

作者： Michael B. Pursley Thomas C. Royster

We evaluate the performance of irregular low-density parity-check (LDPC) codes in slow frequency-hop spread-spectrum systems with nonbinary orthogonal modulation. We also evaluate the performance of two adaptive coding protocols for the LDPC codes. The protocols use information derived by the iterative decoder during the decoding of each packet to select the code rate for the next packet. Performance results are presented for static partial-band noise channels and for partial-band noise channels with time-varying interference bandwidth or power. The adaptive coding protocol is shown to have good performance, even on channels that cause some of the individual codes to exhibit nonmonotonic throughput.

关键词： Parity check codes Frequency Protocols adaptive coding Iterative decoding Spread spectrum communication Modulation coding Interference Bandwidth Throughput

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Performance evaluation of TDMA versus CSMA-based protocols in SINR models

Performance evaluation of TDMA versus CSMA-based protocols i...

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European Wireless Conference

作者： Skander Banaouas Paul Muehlethaler INRIA Rocquencourt Le Chesnay FRANCE

ISBN: (纸本)9781424459353

In this paper, we compare Time Division and Carrier Sense Multiple Access schemes (TDMA and CSMA) in a Signal to Noise and Interference Ratio (SINR)-based model. We assume that the network nodes are distributed a Poisson process evenly distributed and have pending packets. First we study the distribution of the SINR in TDMA-based protocols where the same time-slot is reserved in given radius of n hops (n = 2 in most of these protocols). The same study is carried for CSMA-based access protocols where the reuse is controlled with the carrier-sense threshold. We then compare the total throughput of TDMA and CSMA based access protocols in an outage model. In this model a packet is considered as correctly received if its SINR is above a given threshold. Finally, we conduct the same comparison between TDMA and CSMA-based access protocols in a model of adaptive coding. In this model, the actual SINR rules the transmission coding. We idealize the performance of this technique using the Shannon's well know formula W = W_0log(1 ＋ SINR).

关键词： time division multiple access SINR MAC protocol carrier sense multiple access Performance Evaluation Time division adaptive coding protocols network node Poisson process

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To Code or Not to Code Across Time: Space-Time coding with Feedback

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2008年第8期26卷 1588-1598页

作者： Lin, Che Raghavan, Vasanthan Veeravalli, Venugopal V. Univ Illinois Coordinated Sci Lab Urbana IL 61801 USA Univ Illinois Dept Elect & Comp Engn Urbana IL 61801 USA

Space-time codes leverage the availability of multiple antennas to enhance the reliability of communication over wireless channels. While space-time codes have initially been designed with a focus on open-loop systems, recent technological advances have enabled the possibility of low-rate feedback from the receiver to the transmitter. The focus of this paper is on the implications of this feedback in a single-user multi-antenna system with a general model for spatial correlation. We assume a limited feedback model, that is, a coherent receiver and statistical knowledge at both the ends, along with B bits of error-free quantized channel information at the transmitter. We study space-time coding with a family of linear dispersion (LD) codes that meet an additional orthogonality constraint so as to ensure low-complexity decoding. Our results show that, when the number of bits of feedback (B) is small, a space-time coding scheme that is equivalent to beamforming and does not code across time is optimal in a weak sense in that it maximizes the average received SNR. As B increases, this weak optimality transitions to optimality in a strong sense that is characterized by the maximization of average mutual information. Thus, from a system designer's perspective, our work suggests that beamforming may not only be attractive from a low-complexity viewpoint, but also from an information-theoretic viewpoint.

关键词： adaptive coding diversity methods fading channels feedback communications MIMO systems multiplexing quantization

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To Code or Not to Code Across Time: Space-Time coding with Feedback

To Code or Not to Code Across Time: Space-Time Coding with F...

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42nd Annual Conference on Information Sciences and Systems

作者： Lin, Che Raghavan, Vasanthan Veeravalli, Venugopal V. Univ Illinois Coordinated Sci Lab Urbana IL 61801 USA Univ Illinois Dept Elect & Comp Engn Urbana IL 61801 USA

关键词： adaptive coding diversity methods fading channels feedback communications MIMO systems multiplexing quantization

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3d mesh coding through region based segmentation

3d mesh coding through region based segmentation

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33rd IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Chourou, A. Antonini, M. Benazza-Benyahia, A. Univ Nice Sophia Antipolis I3S Lab CNRS UMR 6070 Nice France URISA SUPCOM Tunis Tunisia

ISBN: (纸本)9781424414833

In this paper, we are interested in wavelet-based coding of 3D semi-regular meshes in order to ensure the progressiveness of the reconstruction. The contribution of this work relies on the adaptation procedure of the lifting scheme operators carried out at each resolution level. More precisely, we propose to firstly segment the original mesh into nonoverlapping regions. The involved predictors are then optimally computed for each region.

关键词： data compression adaptive coding optimization methods mesh generation wavelet transforms

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