K. J. Ray Liu, Ahmed K. Sadek, Weifeng Su et al. · Cambridge University Press eBooks · 2008
In broadband wireless communications, the channel exhibits frequency selectivity (delay spread), resulting in inter-symbol interference (ISI) that can cause serious performance degradation. A mature technique to mitigate the frequency selectivity is to use orthogonal frequency division multiplexing (OFDM), which eliminates the need for high complexity equalization and offers high spectral efficiency. In order to combine the advantages of both the MIMO systems and the OFDM, space–frequency (SF)-coded MIMO-OFDM systems, where two-dimensional coding is applied to distribute channel symbols across space (transmit antennas) and frequency (OFDM tones) within one OFDM block, can be developed to exploit the available spatial and frequency diversity.
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V. Nuri · IEEE Transactions on Circuits and Systems II Analog and Digital Signal Processing · 1998
In this work, a high-quality, space-frequency adaptive, subband image codec is presented. The algorithm jointly optimizes space and frequency segmentation of an image. First, wavelet packets are formed to localize the high-energy frequency bands. Then, the subband coefficients are further classified to maximize the coding gain. The design target is the minimization of Lagrangian cost functions: the cost is the distortion in l/sup 2/ norm and the constraint is the coding rate. The resultant mapping is used to quantize the subband coefficients with trellis coded quantization. This is followed by adaptive arithmetic coding producing the final compressed bitstream. The described approach is tested on several images, and the results are compared to some other compression techniques.
Cited by 2
Vasile Bota, Zsolt Alfréd Polgár, Adão Silva et al. · EURASIP Journal on Wireless Communications and Networking · 2010
Cited by 3Open access
Karim G. Seddik, K. J. Ray Liu · 2007
In this paper, the design of distributed space- frequency codes (DSFCs) implementing the decode-and-forward (DAF) protocol for wireless relay channels is considered. The proposed DSFCs are designed to achieve the frequency and cooperative diversities of the wireless relay channels. A two-hop system model, where there is no direct link from the source node to the destination node, is considered. We propose to use two stages of coding, namely, source node coding and relay nodes coding. The proposed DSFCs are proved to achieve full diversity of order NL where N is the number of relay nodes and L is the number of paths per channel.
Cited by 3
Alessandro Lucas Da Silva, S Teodoro, A Mo o et al. · SHILAP Revista de lepidopterología · 2010
Cited by 0Open access
Zixiang Xiong, Kannan Ramchandran, M.T. Orchard · Kluwer Academic Publishers eBooks · 2006
Cited by 20
Zixiang Xiong, Kannan Ramchandran, M.T. Orchard · IEEE Transactions on Image Processing · 1997
A new class of image coding algorithms coupling standard scalar quantization of frequency coefficients with tree-structured quantization (related to spatial structures) has attracted wide attention because its good performance appears to confirm the promised efficiencies of hierarchical representation. This paper addresses the problem of how spatial quantization modes and standard scalar quantization can be applied in a jointly optimal fashion in an image coder. We consider zerotree quantization (zeroing out tree-structured sets of wavelet coefficients) and the simplest form of scalar quantization (a single common uniform scalar quantizer applied to all nonzeroed coefficients), and we formalize the problem of optimizing their joint application. We develop an image coding algorithm for solving the resulting optimization problem. Despite the basic form of the two quantizers considered, the resulting algorithm demonstrates coding performance that is competitive, often outperforming the very best coding algorithms in the literature.
Cited by 365
Weile Zhang, Feifei Gao, Qinye Yin et al. · IEEE Transactions on Vehicular Technology · 2012
In this paper, we design a space-frequency (SF) convolutional coding scheme for amplify-and-forward (AF) relay networks that contain multiple distributed relay nodes. The frequency-asynchronous nature of the distributed system is considered in our design. Orthogonal frequency-division multiplexing (OFDM) modulation is adopted, which is robust to certain timing errors. We exploit the signal space diversity technique and employ an extended cyclic prefix (CP) at the source node. The relay nodes need to perform only simple operations, e.g., convolution and amplification, and they need no information about the channels and the frequency offsets. Attributed to the extended CP, the multiple frequency offsets can directly be compensated at the destination. We further prove that both spatial and multipath diversity can be achieved by the proposed scheme. Numerical results are provided to corroborate the proposed studies.
Cited by 5
Chao Shao, Cun Yao Xu, Xin Shi · Advanced materials research · 2013
A column orthogonal space-time-frequency coding scheme is presented, its induced cost207 transmit environment channel matrix has greater determinant value, which will lead result in amplifying the signal-to noise ratio of system, and improving the performance of the system. Computer simulations confirm the theory of the article.
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Kaiser, St. · elib (German Aerospace Center) · 2004
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Youjian Liu, Michael P. Fitz, Oscar Y. Takeshita · 2000
this paper, we study the design of space--time codes for frequency selective quasi-static fading channels with nonnegligible ISI. It has been shown by Tarokh et al. [1] that the achievable diversity of a space-- time code designed for flat fading channel is not reduced if it is used in a frequency selective fading channel. However, a full diversity space-time code designed for flat Rayleigh fading channel may not be able to exploit all the available diversities. We propose a design methodology for codes to achieve full diversity L t L r L c , where L t is the number of transmit antennas, L r is the number of receive antennas, and L c is the number of independent ISI taps. First we introduce the concept of the virtual antenna. This idea permits a formalization of the performance criteria. We also propose to use algebraic design theory [2] to find STC that provide full diversity in an ISI channel.
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�. Larsson, Stoica, Lindskog et al. · IEEE International Conference on Acoustics Speech and Signal Processing · 2002
Cited by 12
Rare & Special e-Zone (The Hong Kong University of Science and Technology) · 2003
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Zixiang Xiong, Kannan Ramchandran, M.T. Orchard · IEEE Transactions on Image Processing · 1998
We extend our previous work on space-frequency quantization (SFQ) for image coding from wavelet transforms to the more general wavelet packet transforms. The resulting wavelet packet coder offers a universal transform coding framework within the constraints of filterbank structures by allowing joint transform and quantizer design without assuming a priori statistics of the input image. In other words, the new coder adaptively chooses the representation to suit the image and the quantization to suit the representation. Experimental results show that, for some image classes, our new coder gives excellent coding performance.
Cited by 146
Guosen Yue, Li Zhang, Xiaodong Wang · 2009
We present a multilayer space-time-frequency (STF) coding scheme for wideband multiple-input multiple-output (MIMO) systems employing orthogonal frequency-division multiplexing (OFDM). With multiple receive antennas, we employ an iterative demodulator consisting of a low-complexity multilayer detector and a simple soft combiner. The system performance is optimized by efficient power allocation among layers, as well as interleaver design and extrinsic scaling. The results show that the proposed multilayer STF coding scheme performs close to or even better than the optimized linear dispersion (LD) STF codes with maximum likelihood (ML) decoding. Unlike the existing STF codes, the proposed multilayer STF strategy is a universal scheme that exhibit excellent performance under various system configurations and channel statistics.
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Celal Eşli, G. Ay, B. Özgül et al. · 2004
This paper attempts to provide an evaluation of high performance local area network (HIPERLAN/2), equipped with space-frequency coded transmit diversity. The HIPERLAN/2 physical layer entities with two antennas are simulated for frequency-selective fading channels for the standard's digital modulation schemes of BPSK, QPSK, 16-QAM and 64-QAM. Packet error rate comparisons of HIPERLAN/2 with and without space frequency coding reveal the potential gains and caveats.
Cited by 3
Cristina Ciochina, D. Castelain, David Martín et al. · HAL (Le Centre pour la Communication Scientifique Directe) · 2007
International audience
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Jonathan H. Manton, Yingbo Hua · 2002
It is known that linearly proceding the source symbols prior to their transmission through an FIR channel can facilitate the identification of the channel and improve the source estimates. This paper propounds the use of a new class of linear precoders which explicitly add algebraic redundancy in the frequency domain. These precoders naturally guard against narrowband interference and channel spectral nulls. This paper also demonstrates how these precoders can be used for novel space time coding over MIMO FIR channels.
Cited by 2
Zhenya He · 2008
A simple rate one half Space-Time-Frequency coding and decoding method is proposed.With coding across antenna (spatial),subcarrier (frequency bins) and time together,the coding method can get the full diversity of spatial and frequency.For the special structure of the code,we can simplify the complexity of the computation of matrix inverse.Before making decision of the symbol, with efficient signal combining using noise smoothing,we can get the lower symbol error rate.The simulation results show that our pro- posed STFBC scheme has the better performance than that of the traditional STFBC constructed via the repeated mapping.
Cited by 0
Wei Zhang, Xiang‐Gen Xia, P.C. Ching · 2005
In this paper, we propose a universal design of rate-M <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</inf> full-diversity space-frequency (SF) block codes over MIMO frequency-selective fading channels for any number of transmit antennas. The full-diversity can be proved to be the product of the number of transmit antennas M <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">t</inf> , receiver antennas M <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</inf> and channel taps L. The performance of the proposed SF codes are simulated and compared with some existing SF codes. The full-diversity of the proposed rate-Mt SF block codes is further validated from the simulated cases.
Cited by 5