共查询到20条相似文献,搜索用时 15 毫秒
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随着计算机及通信等技术日新月异的发展,无线图像传输技术得到了广泛的重视。针对视频、图像传输效率低及通信系统性能没有达到最优等问题,在列出了基本概念基础上,本文提出了一种基于最大后验概率的联合信源信道编码算法,经过仿真验证,此方法图像质量比传统方法有所提高。 相似文献
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《Communications, IEEE Transactions on》2005,53(5):905-905
Joint Source/Channel Coding and MAP Decoding of Arithmetic Codes In this paper, a novel MAP estimation approach is employed for error correction of arithmetic codes with a forbidden symbol. The system is founded on the principle of joint source channel coding, which allows one to unify the arithmetic decoding and error correction takes into a single process, with superior performance compared to traditional separated techniques. The proposed system improves the performance in terms of error correction with respect to a separated source and channel coding approach based on convolutional codes, with the additional great advantage of allowing complete flexibility in adjusting the coding rate. The proposed MAP decoder is tested in the case of image transmission across the AWGN channel and compared against standard FEC techniques in terms of performance an complexity. Both hard and soft decodng are taken into account, and excellent result in terms of packet error rate and decoded image quality are obtained. 相似文献
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Since high-quality image/video systems based on the JPEG/MPEG compression standards often require power-expensive implementations
at relatively high bit-rates, they have not been widely used in low-power wireless applications. To alleviate this problem,
we designed, implemented, and evaluated a strategy that can adapt to different compression and transmission rates. (1) It
gives important parts of an image higher priority over unimportant parts. Therefore, the high-priority parts can achieve high
image quality, while the low-priority parts, with a slight sacrifice of quality, can achieve huge compression rate and thus
save the power/energy of a low-power wireless system. (2) We also introduce a priority-driven scheduling approach into our
coding algorithm, which makes the transmission of important parts earlier with more data than other parts. Through a balanced
trade-off between the available time/bandwidth/power and the image quality, this adaptive strategy can satisfy users with
desired images quality and lead to a significant reduction of the important parts’ deadline misses.
相似文献
Feng Shang (Corresponding author)Email: |
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该文根据信源编码压缩比、信道码率及信道特征对渐进图像传输失真的影响,提出一种基于最小图像失真的动态码率分配策略。在总的码率限制下采用遍历搜索信道码率的方法,得出可用码率在信源编码和信道编码之间的最优分配,使端对端的失真最小。 相似文献
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《Communications Letters, IEEE》2008,12(9):678-680
Linear programming (LP) decoding of low-density parity-check codes over discrete memoryless symmetric channels was introduced by Feldman et al. in [1]. Here, we extend the LP decoding paradigm by applying it to two additional scenarios: joint source-channel (JSC) coding and decoding over the infinitememory non-ergodic binary Polya-contagion channel. Simulation results indicate that the JSC LP decoder yields significant gains over the standard LP decoder for non-uniform sources. Simulations also show that the LP decoder for the Polya channel performs moderately well in relation to the ϵ-capacity limit. 相似文献
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This paper presents the effects of condition number ( \(\tau \) ) in communication system performance. It has been shown that a small condition number ( \(\tau \) ) results a better performance. The proposed scheme is using special kind of matrices with Lattice Sphere Decoding (LSD) technique for Block Data Transmission Systems (BDTS). Hankel and Toeplitz matrices are used separately as a channel matrix (H) while circulant matrix is used in the previous works. The proposed scheme reduced the condition number ( \(\tau \) ) and, therefore, improve the system performance. As a result; LSD-based BDTS with Toeplitz/Hankel matrix outperforms the LSD-based BDTS with circulant matrix. Complexity analysis is also done which based on lattice dimension and initial radius selection. 相似文献
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提出一种JPEG图像传输的循环码不等差错保护策略,该策略充分考虑JPEG各部分数据重要性的不同,对比较重要的JPEG数据,使用性能较好的差错控制编码对其进行保护;而对重要性一般的JPEG数据,使用性能一般的差错控制编码。在加性高斯白噪声信道中验证该策略,仿真结果表明该策略能保证JPEG图像的稳健传输。 相似文献
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Hui Jun Chen Lei Cao 《Wireless Communications, IEEE Transactions on》2008,7(3):831-836
For high data rate communications, variable length codes (VLC) and multiple input multiple output (MIMO) techniques are required in the application layer and the physical layer, respectively. In this paper, we study the joint decoding for systems that consist of reversible VLC (RVLC) as the source codes and recursive space time trellis codes (STTC) as the coded modulation. The maximum a posteriori probability (MAP) decoding algorithm is modified to accommodate issues including the inseparable systematic information, the unsymmetric trellis structure, and information in both bit and symbol domains. Further, by converting extrinsic information based on the modulation mode and the mapping method, iterative information exchange can be performed so as to fully utilize the redundancy in both RVLC and recursive STTC. The performance of the proposed joint decoding is evaluated over both rapid fading and quasi- static flat fading channels, which shows significant improvement in coding gain in comparison with the non-iterative receiver. 相似文献
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用ARM926EJ-S处理器实现JPEG图像软件解码 总被引:3,自引:1,他引:2
在分析JPEG编解码原理后,提出基于ARM926EJ-S处理器的JPEG软件解码方案,并对各个模块算法进行优化,改进后的JPEG解码器平均解码性能有了较大提升。 相似文献
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In this paper, we consider a multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system
operating over frequency-selective fading channels. We propose a novel scheme for joint carrier-frequency offset (CFO) and
channel estimation based on the expectation–maximization (EM) algorithm. Furthermore, the Cramer-Rao bounds (CRBs) for both
CFO and channel estimators are exploited to evaluate the performance of the proposed scheme. Computer simulations show that
the proposed algorithm achieves almost ideal performance compared with the CRBs for both channel and frequency offset estimations.
相似文献
M. AhmadianEmail: |
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Universal Source Controlled Channel Decoding with Nonsystematic Quick-Look-In Turbo Codes 总被引:1,自引:0,他引:1
《Communications, IEEE Transactions on》2009,57(4):960-971
Utilization of redundancy left in a channel coded sequence can improve channel decoding performance. Stronger improvement can usually be achieved with nonsystematic encoding. However, nonsystematic codes recently proposed for this problem are not robust to the statistical parameters governing a sequence and thus should not be used without prior knowledge of these parameters. In this work, decoders of nonsystematic quick-look-in turbo codes are adapted to extract and exploit redundancy left in coded data to improve channel decoding performance. Methods, based on universal compression and denoising, for extracting the governing statistical parameters for various source models are integrated into the channel decoder by also taking advantage of the code structure. Simulation results demonstrate significant performance gains over standard systematic codes that can be achieved with the new methods for a wide range of statistical models and governing parameters. In many cases, performance almost as good as that with perfect knowledge of the governing parameters is achievable. 相似文献
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