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THE UNIFICATION OF differential encoding and decoding ALGORITHM FOR VARIOUS SIGNALS

Journal of Electronics(China) 2007年第5期24卷 600-606页

作者： Liu Shuangping Wen Xiang Jin Liang The College of Information Engineering The Information Engineering University Zhengzhou 450002 China

Many monographs point out that differential encoding and decoding is necessary for ef- fectual information transmission against phase ambiguity while seldom discuss the reason why phase ambiguity will emerge *** algorithms are specially designed for certain modulation scheme;these algorithms cannot satisfy the requirement of soft-defined radio,which perhaps demands a uniform algorithm for different *** paper proposes a new opinion on phase ambiguity from the view of *** opinion believes that modulating symbol sequence can affect,at optimum sampling epoch,the modulated waveform as oscillating carrier has done,and so the stochastic sequence leads to phase *** on a general signal model,this paper also puts forward a novel universal algorithm,which is suitable for different signals,even some new ones,by configuring several parameters.

关键词： Soft-defined radio differential encoding and decoding Phase ambiguity

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differential Distributed Space-Time Coding With Imperfect Synchronization in Frequency-Selective Channels

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2015年第4期14卷 1811-1822页

作者： Avendi, M. R. Jafarkhani, Hamid Univ Calif Irvine Ctr Pervas Commun & Comp Irvine CA 92697 USA

differential distributed space-time coding (D-DSTC) is a cooperative transmission technique that can improve diversity in wireless relay networks in the absence of channel information. Conventionally, it is assumed that channels are flat-fading and relays are perfectly synchronized at the symbol level. However, due to the delay spread in broadband systems and the distributed nature of relay networks, these assumptions may be violated. Hence, inter-symbol interference (ISI) may appear. This paper proposes a new differential encoding and decoding process for D-DSTC systems with multiple relays over slow frequency-selective fading channels with imperfect synchronization. The proposed method overcomes the ISI caused by frequency-selectivity and is robust against synchronization errors while not requiring any channel information at the relays and destination. Moreover, the maximum possible diversity with a decoding complexity similar to that of the conventional D-DSTC is attained. Simulation results are provided to show the performance of the proposed method in various scenarios.

关键词： Distributed space-time coding differential encoding and decoding synchronization errors frequency-selective channels relay networks cooperative communications OFDM

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Joint iterative multiuser detection and channel estimation for differentially coded asynchronous CDMA systems

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2008年第1期57卷 380-392页

作者： Talakoub, Shahrarn Shahrrava, Behnam Univ Waterloo Dept Elect & Comp Engn Waterloo ON N2L 3G1 Canada Univ Windsor Dept Elect & Comp Engn Windsor ON N9B 3P4 Canada

In this paper, we propose a receiver structure that performs joint iterative multiuser detection and channel estimation for the uplink of differentially coded asynchronous direct-sequence code-division multiple-access systems in unknown multipath channels. The overall transmission scheme for each user is the serial concatenation of a recursive systematic convolutional (RSC) encoder and a differential encoder separated by an inter-leaver. The proposed receiver consists of two stages. The first stage performs channel estimation, soft interference cancellation, and soft-input soft-output multiuser filtering, followed by the second stage, which consists of a bank of serially concatenated single-user channel decoders and differential decoders. The single-user iterative decoder for each user consists of a powerful combination of an RSC decoder and a differential decoder, which work together in an iterative fashion. In terms of channel estimation, at the first iteration, the multipath channel is blindly estimated by exploiting the orthogonality property between the signal and noise subspaces, whereas, for the next iterations, the channel is estimated using the soft estimates of coded bits of each user provided by the single-user iterative decoders in conjunction with the output of the multiuser detector. By exchanging soft information between the different stages, the receiver performance is improved through iteration. Simulation results demonstrate that the performance of the proposed iterative multiuser detector with the integrated channel estimator approaches the single-user bound at high signal-to-noise ratio.

关键词： code-division multiple-access (CDMA) systems differential encoding and decoding iterative channel estimation turbo multiuser detection

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differential Distributed Space-Time Coding with Imperfect Synchronization

Differential Distributed Space-Time Coding with Imperfect Sy...

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IEEE Global Communications Conference (GLOBECOM)

作者： Avendi, M. R. Poorkasmaei, Sina Jafarkhani, Hamid Univ Calif Irvine Ctr Pervas Commun & Comp Irvine CA 92697 USA

ISBN: (纸本)9781479935123

differential distributed space-time coding (D-DSTC) has been considered to improve both diversity and data-rate in cooperative communications in the absence of channel information. However, conventionally, it is assumed that relays are perfectly synchronized in the symbol level. In practice, this assumption is easily violated due to the distributed nature of the relay networks. This paper proposes a new differential encoding and decoding process for D-DSTC systems with two relays. The proposed method is robust against synchronization errors and does not require any channel information at the destination. Moreover, the maximum possible diversity and symbol-by-symbol decoding are attained. Simulation results are provided to show the performance of the proposed method for various synchronization errors and the fact that our algorithm is not sensitive to synchronization error.

关键词： Distributed space-time coding differential encoding and decoding synchronization error OFDM relay networks

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differential Distributed Space-Time Coding with Imperfect Synchronization

Differential Distributed Space-Time Coding with Imperfect Sy...

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IEEE Global Communications Conference

作者： M. R. Avendi Sina Poorkasmaei Hamid Jafarkhani Center for Pervasive Communications and Computing University of California

ISBN: (纸本)9781479935130

关键词： Distributed space-time coding differential encoding and decoding Synchronization error OFDM Relay networks

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