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International Symposium on High Capacity Optical Networks and Enabling Technologies

作者： Mondal, M. R. H. Majumder, S. P. Bangladesh Univ Engn & Technol Inst Informat & Commun Technol Dhaka 1000 Bangladesh Bangladesh Univ Engn & Technol Dept Elect & Elect Engn Dhaka 1000 Bangladesh

ISBN: (纸本)9781424418282

An analytical approach is presented to determine the impact of time selective fading, tinting jitter and AWGN on a STBC-OFDM system with DQPSK, DPSK and QPSK modulation schemes. The BER performance results are evaluated for different values of fading and jitter variance in presence of single and multiple receiving antennas. The computed results show that the DPSK and QPSK systems suffer higher amount of power penalty than DQPSK system due to the jitter effect. Performance improvement due to application of convolution coding is also reported.

关键词： convolutional coding intersymbol interference MIMO OFDM Rayleigh fading STBC timing jitter

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A personal history of the Viterbi algorithm

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IEEE SIGNAL PROCESSING MAGAZINE 2006年第4期23卷 120-+页

作者： Viterbi, Andrew J. Universidad Carlos III de Madrid MADRID Spain

This paper describes how Andrew J. Viterbi developed a non-sequential decoding algorithm which proved useful in showing the superiority of convolutional codes over block codes for a given degree of decoding complexity. The Viterbi algorithm is now used in most digital cellular phones and digital satellite receivers as well as in such diverse fields as magnetic recoding, voice recognition, and DNA sequence analysis.

关键词： Viterbi decoding block codes computational complexity convolutional codes history Viterbi algorithm decoding complexity nonsequential decoding algorithm Social history convolutional coding complexity classes Viterbi algorithm digital cellular phone Block codes digital satellite receiver Viterbi decoding

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Analogue decoding of tail-biting convolutional codes based on Tanner graph

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ELECTRONICS LETTERS 2006年第20期42卷 1167-1169页

作者： Zahabi, M. R. Meghdadi, V. Cances, J. -P. Univ Limoges XLIM ENSIL F-87068 Limoges France

A scheme is proposed to decode a tail-biting convolutional code based on its Tanner graph, which is traditionally done using a forward-backward MAP algorithm. Therefore, decoding may be performed using a standard sum-product algorithm. With respect to decoding based on trellis, all variables in a Tanner graph are binary, which may lead to complexity reduction. A min-sum algorithm is used to decrease the analogue circuit complexity. Simulation shows there is no significant degradation compared with more complex traditional methods.

关键词： analog circuits convolutional coding DEcoding tail biting

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The impact of convolutional coding on the uplink performance of UMTS air interface

The impact of convolutional coding on the uplink performance...

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6th International Conference on Telecommunication in Modern Cable, Satellite and Broadcasting Services

作者： Moradi, H Ahmadian, M Iran Telecommun Res Ctr Tehran Iran

ISBN: (纸本)0780379632

Third generation of mobile communications systems (3G) integrate a wide variety of wireless services as multimedia services. Universal Mobile Telecommunications System (UMTS) is the main standard of 3G with WCDMA air interface. The WCDMA provides both error detection and error correction as channel coding scheme. The first one is provided by Cyclic Redundancy Check (CRC) coding and the latter by a combination convolutional code with turbo decoding. For convolutional coding, both rate 1/2 and 1/3 are considered. This paper gives simulation observations of rate 1/3 convolutional coding effect on reverse link (uplink) for voice service and compares results with an uncoded system with a description of WCDMA technology and its channel coding scheme. A Rake combiner is implemented in receiver to compensate undesired channel effect and a Viterbi soft decision decoder performs decoding. FDD mode of WCDMA is selected as the operation mode of transmission. Conclusions are shown in Bit Error Rate (BER) curves and no CRC coding or interleaving is used.

关键词： channel coding convolutional coding error correction WCDMA viterbi decoder and spreading

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Effects of digital filtering technique in reducing the effects of clipping of an enhanced orthogonal frequency division multiplexing system

Effects of digital filtering technique in reducing the effec...

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1st International Symposium on Wireless Pervasive Computing

作者： Hassan, Wan Hafiza Wan Khatun, Sabira Multimedia Univ Ctr Fdn Educ & Extens Educ Melaka 7450 Malaysia Univ Putra Malaysia Fac Engn Dept Comp & Commun Syst Serdang 43400 Malaysia

ISBN: (纸本)0780394100

Despite of many advantages of OFDM, it has two main drawbacks which are high peak to average power ratio (PAPR) and synchronization problem. High PAPR causes saturation in power amplifiers, leading to intermodulation products among the sub carriers and disturbing out of band energy. Therefore, it is desirable to reduce the PAPR by means of PAPR reduction schemes. However, it caused the degradation of BER and enhanced the growth of out of band radiation which has led to the degradation of OFDM overall performance In this paper, OFDM system with an enhanced clipping technique has been proposed, the effects of clipping have been analyzed and the system is evaluated by integrating with its significant features including convolutional forward error control coding, oversampled inverse fast fourier transform (IFFT) and digital filtering technique in order to minimize the effects of clipping. It is shown that the bit error rate (BER) of the clipped OFDM signal is improved, the PAPR is further reduced and the effect of out of band radiation is minimized. Besides, other effects of filtering technique are also analyzed in order to optimize the overall performance of our proposed system.

关键词： OFDM PAPR convolutional coding clipping oversampled IFFT FIR filter

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ITERATIVE MULTIUSER DETECTION PERFORMANCE EVALUATION ON A SATELLITE MULTIBEAM COVERAGE

ITERATIVE MULTIUSER DETECTION PERFORMANCE EVALUATION ON A SA...

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European Signal Processing Conference

作者： J.P. Millerioux M.L. Boucheret C. Bazile A.Ducasse University of Pisa

This paper deals with the use of non-linear multiuser detection techniques to mitigate co-channel interference on the reverse link of multibeam satellite systems. The considered system is inspired by the DVB-RCS standard, with the use of convolutional coding. The algorithms consist of iterative parallel interference cancellation schemes with semi-blind channel estimation. We propose a simple approach for statistical evaluation on a multibeam coverage, and present results obtained on a coverage designed on a digital Ka-band focal array feed reflector antenna.

关键词： Coverage reverse link Cochannel interference Performance Evaluation simplicial approximation inspection technique channel blind estimation convolutional coding Statistical Computing Interference cancellation Reflector antennas

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Diversity: On the Evolution to MIMO and Beyond

Diversity: On the Evolution to MIMO and Beyond

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2006 IET Seminar on Waveform Diversity and Design in Communications, Radar and Sonar

作者： T.A. Sturman C. Griffin QinetiQ Limited Malvern UK

ISBN: (纸本)0863417213;9780863417214

This paper considers the evolution to multiple input, multiple output (MIMO) communications, which has its origins in both spatial processing and temporal processing. In the context of this paper, the term 'spatial processing' is taken to include classical/adaptive beamforming and sub-space analysis, whereas the term 'temporal processing' is taken to include the subjects of error control coding, interleaving and equalisation. The objective of this paper is therefore to provide an outline of some of the principal developments within both spatial processing and temporal processing, in order to relate MIMO to the prior art. The emphasis on this paper is on the results which steered this notion of diversity to yield MIMO. The benefits of MIMO have been achieved by integrating the functionality contained within both spatial processing and temporal processing. As shown within this paper, historically, the original motivation within spatial processing was to enhance target location and accuracy in terms of resolution and bias. Temporal processing, in the case of communications engineering, however, was driven by the need to control the number of digital errors between the transmitter and receiver. Each of these two subjects was for a significant number of years treated independently, and excellent process had been made in both. However, a significant barrier within each of these two subjects was the limitation of system processing capability, particularly in terms of both speed and memory. Improvements in the categorisation of physical phenomena associated with a range of wireless channels, and the processing power of recent hardware have enabled the realisation of MIMO to be achieved. As hardware capabilities improve and greater effort is made at the integration of the functionality between the various layers within a communications system, system efficiency and performance can be maximised. The technologies which will be instrumental in achieving this goal are likely to

关键词： Diversity MIMO MUSIC ESPRIT Block codes convolutional codes Interleaving Equalisation and turbo codes multiple input multiple output systems convolutional coding Block codes Multiple signal classification Esapent

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Novel FEC Schemes for UWB: Design, Modelling and Performance Analysis

Novel FEC Schemes for UWB: Design, Modelling and Performance...

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2006 IET Seminar on Waveform Diversity and Design in Communications, Radar and Sonar

作者： V. Lakkundi R. Marsalek Institute of Radio Electronics Brno University of Technology Brno Czech Republic

ISBN: (纸本)0863417213;9780863417214

In this paper, the authors present the design and modelling aspects of UWB turbo codes and UWB SCCCs, along with their performance analysis in comparison with the FEC method recommended by the UWB specifications. The authors consider both the direct spread and multi-carrier versions of UWB in the presence of additive white Gaussian noise (AWGN) channel as well as IEEE 802.15.3 channel models. The results obtained show that UWB turbo codes yield a coding gain of 3-4 dB at an error floor of 10 6 compared to the convolutional encoding and Viterbi decoding (CEVD) method. In addition, UWB SCCC yields a coding gain of 1-2 dB at an error floor of 10 -3 in comparison with the UWB turbo codes. However, convolutional codes perform better than turbo codes at higher signal-to-noise ratios and turbo codes seem to yield a better performance than SCCCs at lower input block sizes

关键词： Wireless personal area networks (WPAN) Ultra wideband communications (UWB) Forward error correction coding (FEC) Turbo codes Serially concatenated convolutional codes (SCCC) turbo codes error floor Ultra wideband technologies coding gain convolutional coding FEC Regimen

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UNEQUAL ERROR PROTECTION OF PCA-CODED FACE IMAGES FOR TRANSMISSION OVER MOBILE CHANNELS

UNEQUAL ERROR PROTECTION OF PCA-CODED FACE IMAGES FOR TRANSM...

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European Signal Processing Conference

作者： Aykut Hocanin Hasan Demirel Sabina Hosic Department of Electrical and Electronic Engineering Eastern Mediterranean University Gazimagusa TRNC via Mersin 10 Turkey. Phone: +90 (392) 630 1438 fax: +90 (392) 365 0240 email: {aykut.hocanin hasan.demirel}@emu.edu.tr

In this paper, a system for reliable communication of coded grey-level face images over noisy channels is proposed. Principal Component Analysis (PCA) is used for face image coding and an unequal error protection (UEP) joint source channel coding scheme is proposed for mobile communication applications. Coded images are protected with convolutional codes for transmission over mobile channels. Recognition rates obtained with UEP system approach the 95% recognition performance for images from the ORL face database.

关键词： COMMUNICATIONS APPLICATION convolutional coding noisy channel

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PHY and MAC performance evaluation of IEEE 802.11a WLAN over fading channels

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IETE JOURNAL OF RESEARCH 2005年第1期51卷 83-94页

作者： Yomo, H Nguyen, CH Kyritsi, P Nguyen, TD Prasad, R Aalborg Univ Ctr TelenFrastruct DK-9920 Aalborg Denmark Acad Finland FIN-02015 Helsinki Finland Aalto Univ FIN-02015 Helsinki Finland

This paper presents an overview of physical (PHY) and medium access control (MAC) layers for IEEE 802.11a, which is a standard of a broadband high-speed wireless local area network (WLAN). IEEE 802.11a uses 5 GHz frequency band and its PHY is based on orthogonal frequency division multiplexing (OFDM). In this paper, we evaluate the OFDM-based PHY and MAC performance of IEEE 802.11a under various practical wideband channel models, which are abstracted from actual propagation measurements. The effects of different transmission modes defined in PHY on the IEEE 802.11 system performance are investigated. We also discuss the impact of link adaptation, which attempts to choose the best-suited transmission mode according to channel conditions, on the overall system performance.

关键词： OFDM IEEE 802.11a HYPERLAN/2 IFFT convolutional coding time dispersive frequency selective wideband rayleigh fading MAC link adaptation

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