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本文提出一种二维相关的非平稳信源模型。在此基础上,设计了一种双扫描自适应编码方案。结合算术编码,利用该自适应方案对报纸传真文件进行编码实验,结果表明自适应编码比固定参数的非自适应编码效率提高30%左右。 相似文献
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本文针对L-Z信源编码算法在对信息序列进行编码分段时,最后部分码段可能与前面的码段重复而不能编码,由此产生丢失数据的情况,提出了修正的方法,将L-Z编码编码时丢失数据的问题予以解决。 相似文献
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本文针对L-Z信源编码算法在对信息序列进行编码分段时,最后部分码段可能与前面的码段重复而不能编码,由此产生丢失数据的情况,提出了修正的方法,将L-Z编码编码时丢失数据的问题予以解决. 相似文献
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提出了采用低密度奇偶校验码的分布式联合信源信道网络编码方案,应用于两源一中继一目的节点的无线传感器网络中.在方案中,信源节点通过传输系统信道码的校验位与部分信息位,同时实现了信源压缩与信道纠错.中继节点有效利用数据的相关性进行译码,并进行部分数据比特删余,减少因中继端网络编码引起的错误传播,仿真验证了方案的有效性.应用了不等差错保护思想,更贴近实际应用场景,利于目的节点进行更好的低误差解码. 相似文献
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信源编码(或数据压缩)可以有效地应用于密码学。本文描述五种信源编码方案。基中三种方案属于通用信源编码类型,可以用来产生强理想密码,实现“通用”多名码代替,测试随机比特发生器,以及强化序列密码的滚动密钥发生器等等。 相似文献
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《Signal Processing: Image Communication》2014,29(1):1-22
In video communication systems, the video signals are typically compressed and sent to the decoder through an error-prone transmission channel that may corrupt the compressed signal, causing the degradation of the final decoded video quality. In this context, it is possible to enhance the error resilience of typical predictive video coding schemes using as inspiration principles and tools from an alternative video coding approach, the so-called Distributed Video Coding (DVC), based on the Distributed Source Coding (DSC) theory. Further improvements in the decoded video quality after error-prone transmission may also be obtained by considering the perceptual relevance of the video content, as distortions occurring in different regions of a picture have a different impact on the user's final experience. In this context, this paper proposes a Perceptually Driven Error Protection (PDEP) video coding solution that enhances the error resilience of a state-of-the-art H.264/AVC predictive video codec using DSC principles and perceptual considerations. To increase the H.264/AVC error resilience performance, the main technical novelties brought by the proposed video coding solution are: (i) design of an improved compressed domain perceptual classification mechanism; (ii) design of an improved transcoding tool for the DSC-based protection mechanism; and (iii) integration of a perceptual classification mechanism in an H.264/AVC compliant codec with a DSC-based error protection mechanism. The performance results obtained show that the proposed PDEP video codec provides a better performing alternative to traditional error protection video coding schemes, notably Forward Error Correction (FEC)-based schemes. 相似文献
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Accumulated low density parity check (LDPCA) codec is proposed for DISCOVER project in distributed video coding (DVC),which offers flexible coding rate.Although it can use feedback channel to adapt the... 相似文献
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Sasan Khoshroo Honggang Wang Liudong Xing Dayalan Kasilingam 《Wireless Communications and Mobile Computing》2015,15(2):389-400
Wireless sensor networks (WSNs) have found a wide variety of applications recently. However, the challenges in WSNs still remain in improving the sensor energy efficiency and information quality (distortion reduction) of the sensing data transmissions. In this paper, we propose a novel cross‐layer design of resource allocation and channel coding to protect distributed source coding (DSC)‐based data transmission. Resource allocation strategies include rate adaptation and automatic repeat‐request retransmissions. Our proposed joint design of resource allocation, channel coding, and DSC can improve the network energy efficiency and information quality while meeting the data transmission latency requirements. Further, we investigate how the resource allocation enables the network to achieve unequal error protection among correlated DSC streams. Our simulation studies demonstrate that the proposed joint design significantly improves the DSC‐based data transmission quality and the network energy efficiency. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Hwan Seok Chung Sun Hyok Chang Bong Kyu Kim Kwangjoon Kim 《Optical Fiber Technology》2008,14(2):130-133
Experimental demonstration of security-improved optical code-division-multiplexed-access (CDMA) scheme based on spectrally encoded incoherent broadband light source with bipolar coding is presented. Incoherent bipolar encoding is achieved with amplified spontaneous emission (ASE) noise of erbium-doped fiber amplifier. We show details of coding scheme and investigate security issues by measuring eye-diagrams and bit-error-rates for various cases. In addition, we present analytical and numerical simulation results for secure transmission of spectrally encoded incoherent optical CDMA signal. 相似文献
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Turbo codes are a promising technique for distributed source coding (DSC) in sensor networks because of their simple encoding implementation and high decoding performance. However, different from a conventional channel decoding scenario, decoding in DSC generally involves different types of distortion from physical and virtual channels. In this letter, we adapt the turbo decoding to handle data mixed with two types of distortion simultaneously. By adjusting the channel reliability values and the calculation of extrinsic information, it will be shown to what extent the decoding with the adaptation outperforms one considering single type of distortion only. Moreover, the adaptation, matching well with the realistic DSC scenario, only requires a slight change for an existing turbo decoding hardware unit. 相似文献
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We consider the joint source–channel coding problem of stereo video transmitted over AWGN and flat Rayleigh fading channels. Multiview coding (MVC) is used to encode the source, as well as a type of spatial scalable MVC. Our goal is to minimize the total number of bits, which is the sum of the number of source bits and the number of forward error correction bits, under the constraints that the quality of the left and right views must each be greater than predetermined PSNR thresholds at the receiver. We first consider symmetric coding, for which the quality thresholds are equal. Following binocular suppression theory, we also consider asymmetric coding, for which the quality thresholds are unequal. The optimization problem is solved using both equal error protection (EEP) and a proposed unequal error protection (UEP) scheme. An estimate of the expected end-to-end distortion of the two views is formulated for a packetized MVC bitstream over a noisy channel. The UEP algorithm uses these estimates for packet rate allocation. Results for various scenarios, including non-scalable/scalable MVC, symmetric/asymmetric coding, and UEP/EEP, are provided for both AWGN and flat Rayleigh fading channels. The UEP bit savings compared to EEP are given, and the performances of different scenarios are compared for a set of stereo video sequences. 相似文献
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Traditional lossless compression methods for satellite hyperspectral imagery focus on exploiting spatial and/or spectral redundancy. Those methods do not consider the temporal redundancy between images of the same area that are captured at different times. To exploit the temporal redundancy between hyperspectral images and reduce the amount of information to be transmitted from the space-satellite to the ground station via the downlink, this paper introduces a dual link distributed source coding (DLDSC) scheme for hyperspectral space-satellite communication. The proposed scheme employs the space-satellite dual link (i.e., the downlink and the uplink). The satellite onboard uses some side information from the ground station to calculate the hyperspectral image band coset values, and then, without syndrome coding, transmits to the ground station via the downlink. Coset coding is a typical technique used in distributed source coding (DSC), and here the coset values represent the timely hyperspectral image details. Typically, the coset values have lower entropy than that of the original source values. To exploit the temporal redundancy, the side information is computed in the ground station using the image captured at the previous time for the same area and transmitted to the space-satellite via the uplink. Hyperspectral images from the Hyperion satellite are used for the validation of the proposed scheme. The experimental results indicate that the proposed DLDSC scheme can reduce the original signal entropy by approximately 3.2 bits per sample (bps) and can achieve up to 1.0 bps and 1.6 bps gains over the lossless JPEG2000 standard and the state-of-art predictive CCSDS-123 method, respectively. 相似文献
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在传统分层系统中,信息数据包首先在数据链路层进行数据包级的检错码编码,然后一个数据包对应一个信息分组在物理层进行符号级的纠错码编码,最后送入信道中传输。为提高系统的传输效率,提出了一种基于数据包合并的物理层与数据链路层编码的跨层优化方案,即数据链路层的多个数据包合并对应物理层的一个信息分组,然后进行纠错编码后再传输。通过理论推导得出了使系统传输效率最大的最优合并数据包个数和数据包长度表达式。通过仿真验证了理论推导的正确性,并与传统方案进行了比较,结果表明,该方案能有效提高系统的传输效率。 相似文献
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This paper addresses the problem of efficient data gathering in wireless sensor networks with a complexity constrained data gathering node. Due to the complexity constraint, the data gathering node employs an asymmetric DSC that (de)compresses the data of a given node exploiting its dependency with a limited number of other nodes. This is characterized in a DSC rate allocation structure that is referred to as limited-order DSC. Within this structure, we investigate the problem of rate allocation for the nodes to maximize the network lifetime. To this end, an algorithm is proposed that is proven optimal with polynomial complexity in terms of number of network nodes. Numerical results demonstrate that the algorithm, even with limited complexity, allows for exploiting most of the achievable compression gain. 相似文献