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Distributed turbo coding with soft information relaying in multihop relay networks

IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 2006年第11期24卷 2040-2050页

作者： Li, Yonghui Vucetic, Branka Wong, Tan F. Dohler, Mischa Univ Sydney Sch Elect & Informat Engn Sydney NSW 2006 Australia Univ Florida Dept Elect & Comp Engn Gainesville FL 32611 USA France Telecom R&D F-38243 Meylan France

It has been shown that distributed turbo coding (DTC) can approach the capacity of a wireless relay network. In the existing DTC schemes, it is usually assumed that error-free decoding is performed at a relay. We refer to this type of DTC schemes as perfect DTC. In this paper, we propose a novel DTC scheme. For the proposed scheme, instead of making a decision on the transmitted information symbols at the relay as in perfect DTC, we calculate and forward the corresponding soft information. We derive parity symbol soft estimates for the interleaved source information when only the a posteriori probabilities of the information symbols are known. The results show that the proposed scheme can effectively mitigate error propagation due to erroneous decoding at the relay. Simulation results also confirm that the proposed scheme approaches the outage probability bound of a distributed two-hop relay network at high signal-to-noise ratios.

关键词： cooperative diversity distributed coding multihop transmission relay network soft information relaying turbo coding wireless sensor network

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turbo coding protection of compressed domain watermarking channel

Turbo coding protection of compressed domain watermarking ch...

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International Conference on Computer as a Tool (EUROCON 2005)

作者： Damnjanovic, I Izquierdo, E Queen Mary Univ London London E1 4NS England

ISBN: (纸本)142440049X

The aim of compression in general is to reduce information spatial and temporal redundancy from the data. From a watermarking point of view, it reduces the watermark insertion space and power of the embedded signal. This paper describes a watermarking scheme based on the spread spectrum paradigm with capacity enhancement using a state-of-the-art error correction technique - turbo coding. A new watermark - composition with random spreading of watermarking bits through the video frames, amplitude adjustment in DCT domain and bit-rate preserving is proposed. However, it was essential to introduce an error correction technique in order to achieve reasonable capacity levels and robustness. In addition, experimental results on perceptibility and robustness on transcoding are presented.

关键词： amplitude adjustment data embedding mpeg2 compression turbo coding watermarking

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Distributed turbo coding and Decoding for Wireless Sensor Networks

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IEEE COMMUNICATIONS LETTERS 2011年第2期15卷 166-168页

作者： Chen, June Abedi, Ali Univ Maine Elect & Comp Engn Dept Orono ME 04469 USA

In this article a distributed turbo coding and iterative decoding scheme is introduced. The proposed scheme with low complexity is suitable for wireless sensor networks applications where many sensors sense similar sources resulting in correlated data sampling. Encoders reside in these sensor nodes which are close to the source, while decoders reside in another group of nodes acting as distributed decoder and relay. The decoder structure is presented using a simple suboptimal solution derived from the maximum a posteriori probability decision rule. Simulation results demonstrates a marked bit error performance at high signal to noise ratios.

关键词： Distributed codes wireless sensor networks correlated sources distributed decoding iterative decoding turbo coding MAP decision rule

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Self-encoded spread spectrum and turbo coding

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JOURNAL OF COMMUNICATIONS AND NETWORKS 2004年第1期6卷 9-18页

作者： Jang, WM Nguyen, L Hempel, M Univ Nebraska Peter Kiewit Inst Informat Sci Technol & Engn Dept Elect & Comp Engn Lincoln NE 68583 USA

Self-encoded multiple access (SEMA) is a unique realization of random spread spectrum. As the term implies, the spreading code is obtained from the random digital information source instead of the traditional pseudo noise (PN) code generators. The time-varying random codes can provide additional security in wireless communications. Multi-rate transmissions or multi-level grade of services are also easily implementable in SEMA. In this paper, we analyze the performance of SEMA in additive white Gaussian noise (AWGN) channels and Rayleigh fading channels. Differential encoding eliminates the BER effect of error propagations due to receiver detection errors. The performance of SEMA approaches the random spread spectrum discussed in literature at high signal to noise ratios. For performance improvement, we employ multiuser detection and turbo coding. We consider a downlink synchronous system such as base station to mobile communication though the analysis can be extended to uplink communications.

关键词： spread spectrum CDMA multiuser detection random sequence turbo coding

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Higher Order Modulation and turbo coding for GSM/EDGE Continued Evolution

Higher Order Modulation and Turbo Coding for GSM/EDGE Contin...

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64th IEEE Vehicular Technology Conference

作者： Axnas, Johan de Bruin, Peter Eriksson, Stefan Jonsson, Tomas Sundberg, Marten Thurfjell, Magnus Ericsson Res Stockholm Sweden

ISBN: (纸本)9781424400621

GSM/EDGE is the world's largest and most widespread cellular technology. EDGE offers an attractive solution for 3(rd) generation cellular services in existing GSM networks. The introduction of new services into an existing network typically leads to increased capacity demands, since more users of different service types need to coexist in limited spectrum, while the existing speech service is required to function at least as well as before. Higher Order Modulation in combination with turbo coding is proposed to substantially enhance spectrum efficiency and average user bit rates in GSM/EDGE through improved interference robustness and increased peak bit rates. Simulation results indicate link level gains of 2.5-5.5 dB. When additionally applying incremental redundancy, similar relative improvements are shown. Bit rates can be increased by more than 30%, at C/I levels above 30dB. System performance gains are indicated by average user bit rate enhancements of up to 30-40%, along with substantial gains in spectrum efficiency, up to 40%. It is also shown that system gains are rather insensitive to frequency reuse and whether frequency hopping is applied or not (in sparse reuse scenarios).

关键词： EDGE Modulation 16QAM turbo coding

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Use of turbo coding for embedded transmission scheme in optical CDMA

Use of turbo coding for embedded transmission scheme in opti...

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IEEE Region 10 Conference (TENCON 2005)

作者： Arai, Tomoyuki Kamakura, Koji Yashiro, Kenichiro Chiba Univ Dept Elect & Mech Engn 1-33 Yayoi Inage Chiba 2638522 Japan

ISBN: (纸本)9780780393110

We propose using turbo code for the embedded transmission (ET) scheme [1][2] in optical code division multiple access (CDMA). Although the scheme uses pulse position modulation (PPM), to resolve the problem of the vulnerability of the embedded PPM signaling to multiple access interference (MAI), we obtain soft information of the received signal, which is used for turbo decoding. We evaluate the bill error rate (BER) of the proposed scheme, compared the conventional PPM-OCDMA with turbo coding and the ET scheme with BCH coding. Simulation results show that the proposed scheme achieves better BER than the conventional turbo-coded PPM-OCDMA and than the BCH-coded ET scheme.

关键词： turbo coding embedded transmission (ET) scheme pulse position modulation (PPM) code division multiple access (CDMA) multiple access interference (MAI)

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Performance Analysis of a SIMO Wireless Link with turbo coding 4

Performance Analysis of a SIMO Wireless Link with Turbo Codi...

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4th International Conference on Electrical Engineering and Information and Communication Technology (iCEEiCT)

作者： Halim, Md Addul Majumder, Satya Prasad Mil Inst Sci & Technol Dept Elect Elect & Commun Engn Dhaka Bangladesh Bangladesh Univ Engn & Technol Dept Elect & Elect Engn Dhaka Bangladesh

ISBN: (纸本)9781538682791

Performance analysis is carried out for a wireless communication system with single transmitter and multiple receiving antenna diversity over a Rayleigh fading channel with turbo error correction coding. Performance analysis includes the development of bit error rate (BER) expression analytically. Performance results are evaluated in terms of bit error rate (BER) as a function of signal to noise ratio (SNR) for different system parameters like number of receiving antenna, fading parameters and doppler frequency shift along with different free distance of the code. Significant improvement is found in receiver performance over Rayleigh fading channel due to incorporation of turbo coding in the presence of receive diversity with maximum ratio combining. The improvement occurs in terms of lowering of the BER floor which can not be lowered even by increasing number of receiving antenna. Order of improvement in BER floor is around 10-3 to 104. Further there are improvement in receiver performance in terms of coding gain. At a given BER, 10-3, the amount of coding gain is found to be 2 dB to 20 dB depending on the value of the system parameters and the free distance of the code. The results will find applications in the design of SIMO wireless comm. System with turbo coding.

关键词： BER SIMO Doppler shift frequency turbo coding

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Influence of Phase Error on OFDM-based 4096-QAM with turbo coding 32

Influence of Phase Error on OFDM-based 4096-QAM with Turbo C...

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32nd International Conference on Information Networking (ICOIN)

作者： Tian, Ruxiao Ota, Tomoki Otsuka, Hiroyuki Kogakuin Univ Grad Sch Engn Shinjuku Ku Tokyo 1638677 Japan

ISBN: (纸本)9781538622902

The use of higher-order quadrature amplitude modulation (QAM) is an important approach for increasing data rates within a limited bandwidth. However, higher-order QAM is very sensitive to the amplitude and phase error, and needs to higher received SNR. This paper investigates the influence of phase error on the orthogonal frequency division multiplexing (OFDM)-based 1024- and 4096-QAM with turbo coding. The BER performance and the SNR penalty in the presence of the phase error are highlighted as parameters of the coding rates by link-level simulation for both OFDM-based 1024- and 4096-QAM.

关键词： Mobile communication OFDM 1024-QAM 4096-QAM turbo coding Phase error

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Adaptive Modulation and turbo coding for 3GPP LTE Systems with Limited Feedback 79

Adaptive Modulation and Turbo Coding for 3GPP LTE Systems wi...

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IEEE 79th Vehicular Technology Conference (VTC-Spring)

作者： Manolakis, Konstantinos Gutierrez-Estevez, M. A. Jungnickel, Volker Tech Univ Berlin Dept Telecommun Syst Berlin Germany Fraunhofer Heinrich Hertz Inst Berlin Germany

ISBN: (纸本)9781479944828

Link adaptation is recognized as a powerful technique for enhancing spectral efficiency over wireless channels. While its theoretical aspects are well understood, it is not clear yet how to practically deal with limited feedback. In this paper, we study a frequency-selective link adaptation scheme for orthogonal frequency division multiplexing (OFDM). The modulation order is adjusted per resource block (smallest time-frequency unit assigned to a user), while a joint coding rate is used for all variable-length codewords, comprising resource blocks with different modulations. In order to meet the required coding rate, adaptive puncturing is applied after a fixed-rate turbo encoder. Link adaptation is guided by an effective signal-to-noise ratio (SNR), which is calculated over several subcarriers by a mapping function. 3GPP LTE compliant link-layer simulations were performed for optimizing the SNR interface so that the spectral efficiency is maximized under a codeword error rate constraint and tradeoffs between feedback savings and spectral efficiency losses were elaborated. The result is a thoroughly tested link-layer abstraction for 3GPP LTE including adaptive modulation and bit-interleaved coding that can be also used for system-level simulations towards future mobile radio systems.

关键词： 3G mobile communication Long Term Evolution OFDM modulation adaptive modulation interleaved codes telecommunication links turbo codes variable length codes wireless channels 3GPP LTE systems OFDM SNR bit-interleaved coding codeword error rate frequency-selective link adaptation scheme joint coding rate mobile radio systems orthogonal frequency division multiplexing signal-to-noise ratio spectral efficiency turbo coding variable-length codewords Adaptation models Channel coding Fading Modulation Signal to noise ratio

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Random Interleaver Design in turbo coding for Digital Magnetic Recording Channel

Random Interleaver Design in Turbo Coding for Digital Magnet...

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36th International Convention on Information and Communication Technology, Electronics and Microelectronics (MIPRO)

作者： Stancescu, St. Sandu, C. Univ Politehn Bucuresti Bucharest Romania

ISBN: (纸本)9789532330762

turbo codes interleaver logic is analyzed in Digital Magnetic Recording (DMR) Partial Response (PR) channels environment. The performances of turbo encoding/decoding process are estimated, in the presence of appropriate DMR noise, generally a particulate noise, manifested as burst errors of various intensities and dimensions. Depending of interleaver, turbo code performance (Bit Error Rate BER) is estimated, in presence of noise, over variations with its parameters. Optimal code length and structures design recommendations are obtained, related to required recording densities and Signal Noise Ratio (SNR) ranges.

关键词： turbo coding interleaver magnetic recording

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