共查询到20条相似文献,搜索用时 15 毫秒
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《Wireless Communications, IEEE Transactions on》2009,8(6):2771-2775
Recently, a full rate orthogonal space-time block code achieving full diversity while preserving low decoding complexity with very limited feedback was proposed. Based on a feedback of only p?1 bits, these codes exhibit a higher coding gain as well. In this work, we propose a low complexity, though close to optimal, feedback selection scheme. Furthermore, we analyze the performance of these codes with arbitrary number of transmit and receive antennas. We show that with this feedback based codes full diversity of nT nRp is obtained. Finally, we provide closed form expressions for the ergodic and outage mutual information as well as error rates. 相似文献
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Jabran Akhtar 《Circuits, Systems, and Signal Processing》2010,29(2):311-330
This paper considers radar signaling schemes for cancellation of late time arriving echoes. Signal reflections arriving delayed
at the radar when the radar has already emitted a next pulse result in range ambiguities and materialize as potential false
targets. In this work we put forward alternative waveform encoding schemes enabling a well-defined radar system to double,
triple or quadruple the pulse repetition frequency (PRF) with full suppression of emerging range ambiguities. The proposed
techniques thus have the potential to overcome the contradiction often faced in radar and synthetic aperture radar setups
between selecting a low or high value for the PRF. The methods introduced require only simple matched filtering operations
at the receiver and permit usage of arbitrary waveforms with potential for waveform diversity gains. 相似文献
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Maximum-likelihoodBlockDetectionforCPMSignalsWuXuenongANDFengGuangzeng(DepartmentofRadioEngineenng,NanjingUniversityofPostsan... 相似文献
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针对全盲条件下正交空时分组码(OSTBC)的正交性识别问题,提出一种基于高阶累积量的OSTBC识别方法.通过对接收信号白化,在不需要信道估计的情况下,消除信道对识别结果的干扰,既减少了算法复杂度,又提高了低信噪比条件下OSTBC的识别概率;考虑实际系统中噪声对识别结果的影响,利用高阶累积量(阶数大于2)的去噪声特性,消除噪声对于STBC正交特性识别的影响;分析了两种四阶累积量的OSTBC识别特性,选取了适用于OSTBC识别的四阶累积量作为特征参数.仿真结果表明,所提出方法对于OSTBC识别问题区分性能较好. 相似文献
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Orthogonal Transform Coding System for Television Signals 总被引:3,自引:0,他引:3
We discuss orthogonal transformation as a method to compress frequency bandwidth for TV signals. We indicate that the slant orthogonal transformation derived from Hadamard matrix is most advantageous for compression of TV signal bandwidth. Results of simulation show that unweighted Sp-p/Nq rms of approximately 32 dB was obtained with 2.5 bits per sample on picture showing human face. 相似文献
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We present an iterative decoding/demodulation technique for an orthogonal space-time coded continuous-phase modulation (OST-CPM) system. A low-complexity soft input and soft output (SISO) demodulator is developed based on the bidirectional soft output Viterbi algorithm (BSOVA) for the multiple antennas CPM systems. By taking advantage of the orthogonal structure, the complexity of extrinsic information extraction can be significantly reduced at each iteration.Shengli Fu received the B.S. and M.S. degree in telecommunication engineering from Beijing University of Posts and Telecommunications, Beijing, China, in 1994 and 1997, respectively. In 2000, he enrolled at the Wright State University, Dayton, OH, where he received the M.S. degree in Computer Engineering. He currently pursues his Ph.D. degree in the Department of Electrical and Computer Engineering at the University of Delaware.His research interests include information and coding theory, MIMO wireless communication systems, and acoustic and visual signal processing.Genyuan Wang received B.Sc and MS. degrees in Mathematics from the Shanxi Normal University, Xian, China, in 1985 and 1988, respectively, and his Ph.D. degree in Electrical Engineering from Xidian University, Xian China, in 1998.From July, 1988 to September 1994, he worked at Shanxi Normal University as an Assistant Professor and then an Associate Professor. From September 1994 to May 1998, he worked at Xidian University as a research assistant. Currently, he is Post-Doctoral Fellow at Department of Electrical and Computer Engineering, University of Delaware. His research interests are radar imaging and radar signal processing, adaptive filter, OFDM system, channel equalization and space-time coding.Xiang-Gen Xia (M97,S00) received his B.S. degree in mathematics from Nanjing Normal University, Nanjing, China, and his M.S. degree in mathematics from Nankai University, Tianjin, China, and his Ph.D. degree in Electrical Engineering from the University of Southern California, Los Angeles, in 1983, 1986, and 1992, respectively.He was a Senior/Research Staff Member at Hughes Research Laboratories, Malibu, California, during 1995--1996. In September 1996, he joined the Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware, where he is a Professor. He was a Visiting Professor at the Chinese University of Hong Kong during 2002–2003. Before 1995, he held visiting positions in a few institutions. His current research interests include space-time coding, MIMO and OFDM systems, and SAR and ISAR imaging. Dr. Xia has over 100 refereed journal articles published, and 6 U.S. patents awarded. He is the author of the book Modulated Coding for Intersymbol Interference Channels (New York, Marcel Dekker, 2000).Dr. Xia received the National Science Foundation (NSF) Faculty Early Career Development (CAREER) Program Award in 1997, the Office of Naval Research (ONR) Young Investigator Award in 1998, and the Outstanding Overseas Young Investigator Award from the National Nature Science Foundation of China in 2001. He also received the Outstanding Junior Faculty Award of the Engineering School of the University of Delaware in 2001. He is currently an Associate Editor of the IEEE Transactions on Mobile Computing, the IEEE Signal Processing Letters, the IEEE Transactions on Signal Processing, the International Journal of Signal Processing, and the EURASIP Journal of Applied Signal Processing. He was a guest editor of Space-Time Coding and Its Applications in the EURASIP Journal of Applied Signal Processing in 2002. He is also a Member of the Signal Processing for Communications Technical Committee and the Sensor Array and Multichannel (SAM) Technical Committee in the IEEE Signal Processing Society. 相似文献
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为了降低连续相位调制(Continuous Phase Modulation,CPM)信号多符号非相干检测的运算复杂度,提出了一种低复杂度的最大似然块检测算法。该算法充分利用已判决输出的符号对检测过程中的符号向量取值进行约束,有效减少判决统计量计算时的运算量,进而降低算法复杂度。另外,该算法引入判决长度变量,通过调整单次检测时判决符号数使算法能够在检测性能与运算量之间灵活折中。仿真结果表明,提出的低复杂度检测算法能够适用于全响应和部分响应CPM信号,相比原最大似然块检测算法能够在不损失检测性能的前提下降低算法运算量至少50〖WT《Times New Roman》〗%〖WTBZ〗,并且能够通过选择不同的判决长度提高算法应用的灵活性。 相似文献
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The statistical block protection coding scheme [2] for protecting DPCM encoded speech signals through noisy channels has been extended to accommodate DPCM-AQF encoded speech, where AQF stands for adaptive quantization with forward (explicit) transmission of step size. Signal-to-noise ratio (SNR) gains, typically 12 dB, have been achieved over a dynamic range> 20 dB for a bit error rate (BER) of 1.4 percent and the SNR improvement is found to increase with BER. Perceptual improvements in decoded speech have a good correspondence with the gains in SNR. The penalty for this substantial enhancement in the performance of the DPCM-AQF system is an increase in transmission bit rate of 3.5 percent and encoding delay of 64 ms. 相似文献
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In this letter, we propose a novel space-time coding scheme for fast time-variant direct-sequence code-division multiple access (DS-CDMA) channels. The proposed scheme employs multi-chip differential space-time block coding (MC-DSTBC) and robustness against fast fading is further improved by low-complexity decision-feedback differential detection (DF-DD). Both analytical and simulation results show in good agreement the excellent performance of the novel design in fast time-variant channels. 相似文献
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Yeo‐Jin Yoon Seung‐Won Jung Hahyun Lee Hui Yong Kim Jin Soo Choi Sung‐Jea Ko 《ETRI Journal》2012,34(1):106-109
In this letter, we propose a new prediction block filter that can reduce errors between the original and prediction blocks. The proposed filter adaptively adjusts filter coefficients by using the previously reconstructed adjacent blocks and their prediction blocks. Then, the filter is selectively applied to the current prediction block according to the rate‐distortion optimization. Moreover, since the same filter coefficients can be derived in the decoder, they are not encoded into the bit‐stream. The proposed method achieves a 4.65% bitrate saving on average compared with H.264/AVC. 相似文献
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A two-dimensional, 32nd-order orthogonal transform coding system which performs three types of transformations in realtime for NTSC color television signals has been developed. This paper reports on a hardware realization of this system, the optimum bitassignments for 32 and 22 Mbit/s transmission rates and the effects of bit errors during transmission. Through the evaluation of picture quality, the system gave a fine quality of pictures after compressing an 8-bit digitized television signal into 3 bits/pel corresponding to 32 Mbit/s transmission, and a passable quality of pictures by 2.25 bits/ pel corresponding to 22 Mbit/s transmission. 相似文献
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为了抑制空时分组编码系统中的共道用户多址干扰,对低复杂度的多用户检测算法进行了研究,提出了基于概率数据辅助(Probabilistic Data Association,PDA)算法的大容量多用户检测技术。通过充分利用干扰信号的相关性进行有效干扰抑制,从增加共道用户的角度来提高系统容量。仿真表明,该检测技术能进一步提高系统性能,尤其是增大了通信系统容量。 相似文献
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In this paper, a novel trellis source encoding scheme based on punctured ring convolutional codes is presented. Joint source and channel coding (JSCC) using trellis coded continuous phase modulation (CPM) with punctured convolutional codes over rings is investigated. The channels considered are the additive white gaussian noise (AWGN) channel and the Rayleigh fading channel. Optimal soft decoding for the proposed JSCC scheme is studied. The soft decoder is based on the a posteriori probability (APP) algorithm for trellis coded CPM with punctured ring convolutional codes. It is shown that these systems with soft decoding outperform the same systems with hard decoding especially when the systems operate at low to medium signal-to-noise ratio (SNR). Furthermore, adaptive JSCC approaches based on the proposed source coding scheme are investigated. Compared with JSCC schemes with fixed source coding rates, the proposed adaptive approaches can achieve much better performance in the high SNR region. The novelties of this work are the development of a trellis source encoding method based on punctured ring convolutional codes, the use of a soft decoder, the APP algorithm for the combined systems and the adaptive approaches to the JSCC problem. 相似文献
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In this paper, we present channel estimation methods for space-time block coding (STBC) transmissions using constant modulus
algorithm (CMA). The channel estimates are directly calculated from the convergence value of the CMA. Two algorithms using
the channel-vector-based and channel-gain-based constant modulus (CM) criteria are proposed. An approximation of the CM cost
function is introduced to allow the use of the recursive least-square (RLS) technique in designing fast RLS-CMA's. Performance
of the proposed schemes is evaluated and compared with others using simulation. Illustrative results show that the proposed
scheme outperforms the cross-correlated method and can approach the performance of the training-based method. 相似文献
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改进的块截断图象编码算法 总被引:1,自引:0,他引:1
已经提出了的各种块截断算法本质上都是两电平量化器,由于它们将图象简单地量化(或截断)成两个电平值,所以在译码图象中出现矢真,为减少这种失真,本文在块截算法中采用于平滑滤波器,从而改进了现有块共怕算法的性能,明显提高了译码图象质量。 相似文献