共查询到19条相似文献,搜索用时 171 毫秒
1.
2.
针对无线异构网络中进行视频无线传输遇到的网络拥塞、传输丢失等问题,提出了低编码复杂度分级编解码传输方案,基于逐级优化理论和可分级编码理论,设计了视频分级编码策略:利用小波变换后的不同分解层不同子带构成基本层(Base Layer,BL)和三个增强层,获得了码率分级和质量分级的特性.实验结果证明,随着不同层的更新,视频分级系统的解码质量和整体率失真性能都逐级改善.该传输方案实现了在信道条件动态变化的无线网络环境下仍能流畅传输并接收到有用信息,适用于信道条件不稳定的无线异构网络. 相似文献
3.
4.
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
5.
6.
7.
8.
针对经典保密通信中信息安全传输的问题,提出了一种基于循环码和信息压缩的量子保密通信算法。首先,发送端对传输的信息进行预处理,将其分割为长度不等的2组数据,分别用于循环编码和压缩编码。然后,发送端添加一串量子态传输至接收端,采用误码数作为信道安全检测的依据,若信道安全,则对预处理后的数据量子态处理,利用量子稳定子码编码分段并传输,依据稳定字码的特性克服环境引起的误码。最后,接收端接收到量子信息后进行解码,并解循环和解压缩从而获得数据。安全性分析表明,所提量子保密通信算法能较好地抵抗篡改和截断信息的攻击。仿真结果表明,对于数据压缩部分按5分段能获得较好的效果。 相似文献
9.
10.
基于PSK的非对称物理层网络编码 总被引:1,自引:1,他引:0
在非对称的双向中继传输中,传统的基于比特异或的网络编码方案并不能取得最好的性能。一个简单的例子就可以说明传统的补零异或方案的缺陷,而导致这种缺陷的原因是设计自由度的缺乏。一种基于PSK的网络编码方案,配合解调前解码的方案,能够取得良好的性能,并且大大的简化非对称物理层网络编码方案的设计。而且这种方案能够方便的被用于有信道编码的系统,仅仅给系统带来少量的额外负担。 相似文献
11.
This paper investigates the problem of constructing a secret error-correcting multisource network coding scheme against an adversary that can re-select the μ tapping links in different time slice and inject z erroneous packets into network, and the network suffers from ρ packet erasures. In our network scenario, multiple sources transmit information to one or more receivers and these receivers request the information from all the sources. Firstly, a necessary condition is derived for keeping the transmitted information from multisource nodes are secret from the eavesdropper, while the network is only subject to the eavesdropping attack. Subsequently, we provide two multisource network coding schemes for error and erasure correction which can decode the transmitted information correctly. After that, a secret and reliable multisource network coding is proposed. This scheme can retrieve the original information secretly and accurately from the corrupt and deficient information. Meanwhile, it can obtain an asymptotic achievable rate of k ? 2z ? ρ ? 3μ. Moreover, the intermediate nodes are oblivious to the concrete encoding and decoding algorithms implement in source and destination nodes. Finally, security and performance analyses illustrate the advantages of our proposed scheme. 相似文献
12.
A Network Coding Approach to Cooperative Diversity 总被引:5,自引:0,他引:5
Lei Xiao Fuja T. Kliewer J. Costello D. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2007,53(10):3714-3722
This paper proposes a network coding approach to cooperative diversity featuring the algebraic superposition of channel codes over a finite field. The scenario under consideration is one in which two ldquopartnersrdquo - node A and node B - cooperate in transmitting information to a single destination; each partner transmits both locally generated information and relayed information that originated at the other partner. A key observation is that node B already knows node A's relayed information (because it originated at node B) and can exploit that knowledge when decoding node A's local information. This leads to an encoding scheme in which each partner transmits the algebraic superposition of its local and relayed information, and the superimposed codeword is interpreted differently at the two receivers i.e., at the other partner and at the destination node, based on their different a priori knowledge. Decoding at the destination is then carried out by iterating between the codewords from the two partners. It is shown via simulation that the proposed scheme provides substantial coding gain over other cooperative diversity techniques, including those based on time multiplexing and signal (Euclidean space) superposition. 相似文献
13.
Ali El Arab Jean-Claude Carlach Maryline Hélard 《Wireless Personal Communications》2013,72(3):1587-1601
This paper describes a new space-time coding scheme for non-coherent multi-antenna multi-input multi-output (MIMO) systems. This new MIMO scheme merges error-correcting and space-time coding functions by transmitting invertible matrices, so this scheme has been called “Matrix Coded Modulation” or “MCM”. Coherent systems require channel state information (CSI) at the transmitters and/or at the receivers, and their performances strongly depend on the channel estimation. For example, in systems using Orthogonal frequency division multiplexing, the channel estimation requires the insertion of pilot-symbols in the transmitted frame which implies a spectral efficiency loss of the global system that increase with the number of transmit antennas. The existing non-coherent schemes such as the differential space-time modulation leads to performance degradation compared to coherent systems in which perfect CSI is assumed. Decoding in the MCM scheme is performed iteratively, based on a specified detection criteria. In the proposed MCM scheme, decoding can be achieved with or without CSI at the receiving antennas. As the space-time coding function is merged with the error-correcting code, the euclidean distances distribution between modulated signals based on the detection criteria is strongly linked to the Hamming weights distribution of the channel error-correcting code used in the MCM scheme. Moreover, a low-complexity decoding algorithm is described and compared to the existing differential schemes. 相似文献
14.
通过理论分析,看出基于反馈的重传方法比定量重传的方法有更低的解码延迟。提出了一种新型的基于反馈的网络编码(FNC)重传机制,利用seen机制中的隐含信息来获取接收方解码所需的重传分组个数,并改变了编码规则使部分分组可以提前解码。该机制不仅可以处理有固定误码率的随机分组丢失,还可以有效地应对大量突发性分组丢失。仿真结果显示,该机制在高误码率下也能保持较高的吞吐量,且极大地减少了解码延迟,传输过程基本不受分组丢失的影响,有效地对拥塞控制协议隐藏了链路错误。算法简单有效,更适于在实际系统中应用。 相似文献
15.
Collaborative decoding is an approach that can achieve diversity and combining gain by exchanging decoding information among a cluster of physically separated receivers. On AWGN channels, the least-reliable-bits (LRB) exchange scheme can achieve performance close to equal-gain combining (EGC) of all received symbols from all receivers, while reducing the amount of information that must be exchanged. In this paper, we analyze the error performance of collaborative decoding with the LRB exchange scheme when nonrecursive convolutional codes are used. The analysis is based on the observation that the extrinsic information generated in the collaborative decoding of these convolutional codes can be approximated by Gaussian random variables. A density-evolution model based on a single maximum a posteriori decoder is used to obtain the statistical characteristics of the extrinsic information. With the statistical knowledge of the extrinsic information, we develop an approximate upper bound for the error performance of the collaborative decoding process. Numerical results show that our analysis gives very good predictions of the bit error rate for collaborative decoding with LRB exchange. At high signal-to-noise ratios collaborative decoding with properly chosen parameters can achieve the same error performance as EGC of all received symbols from all receiving nodes. 相似文献
16.
从研究APD光电检测接收机被检测光场的量子统计模型出发,构造了一种适用于强度调制/直接检测的自由空间光通信系统中LDPC译码的精确实现方法.该方法在APD接收机输出统计模型(Webb-Gaussian模型)的基础上,推导了M-PPM的LDPC译码算法中初始似然比值的精确计算方法,并给出了详细的译码过程.理论分析和仿真结果表明,与目前普遍采用的APD近似非对称Gaussian统计模型下的译码性能相比较,在相同的信道条件下,该方法可以获得大约1~2 dB的性能增益.这为进一步提高自由空间光通信系统的性能提供了一定的理论依据. 相似文献
17.
Combining network coding and compressed sensing for error correction in wireless sensor networks
下载免费PDF全文
![点击此处可从《International Journal of Communication Systems》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Siguang Chen Meng Wu Kun Wang Zhixin Sun Weifeng Lu 《International Journal of Communication Systems》2015,28(7):1303-1315
As the spatial and temporal correlations of sensor readings are common in wireless sensor networks, motivated by these features and the drawbacks of network coding (NC), we introduce compressed sensing (CS) into NC scheme and construct a cooperating coding mechanism, which performs over different data fields with a compatible transformation measure for the combination of NC and CS. This cooperating coding scheme can reduce the amount of redundant information transmission significantly, because the temporal and spatial correlations are explored fully. Meanwhile, the erasures and errors are considered simultaneously in relay transmission process; a NC decoding for error control is proposed to correct the erasures and errors. Although the decoding error of NC is existent, this error can be further reduced by the reconstruction process of CS; as a result, the relative recovery error is small enough in the sink. Finally, the reliability and performance analyses confirm that the proposed cooperating coding scheme obtains considerable compression gain as compared with conventional coding scheme of NC and transmits information reliably with high recovery precision. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
18.
Ali El Arab Jean-Claude Carlach Maryline Hélard 《Wireless Personal Communications》2013,71(4):2475-2489
This paper describes a new space-time coding scheme for non-coherent multi-antenna Multi-Input Multi-Output (MIMO) systems. This new MIMO scheme merges error-correcting and space-time coding functions by transmitting invertible matrices, so this scheme has been called “Matrix Coded Modulation” or “MCM”. Coherent systems require Channel State Information (CSI) at the transmitters and/or at the receivers, and their performances strongly depend on the channel estimation. For example, in systems using Orthogonal Frequency Division Multiplexing, the channel estimation requires the insertion of pilot-symbols in the transmitted frame which implies a spectral efficiency loss of the global system that increase with the number of transmit antennas. The existing non-coherent schemes such as the Differential Space-Time Modulation leads to performance degradation compared to coherent systems in which perfect CSI is assumed. Decoding in the MCM scheme is performed iteratively, based on a specified detection criteria. In the proposed MCM scheme, decoding can be achieved with or without CSI at the receiving antennas. As the space-time coding function is merged with the error-correcting code, the euclidean distances distribution between modulated signals based on the detection criteria is strongly linked to the Hamming weights distribution of the channel error-correcting code used in the MCM scheme. Moreover, a low-complexity decoding algorithm is described and compared to the existing differential schemes. 相似文献
19.
The throughput gain obtained by linear network coding (LNC) grows as the generation size increases, while the decoding complexity also grows exponentially. High decoding complexity makes the decoder to be the bottleneck for high speed and large data transmissions. In order to reduce the decoding complexity of network coding, a segment linear network coding (SLNC) scheme is proposed. SLNC provides a general coding structure for the generation-based network coding. By dividing a generation into several segments and restraining the coding coefficients of the symbols within the same segment, SLNC splits a high-rank matrix inversion into several low-rank matrix inversions, therefore reduces the decoding complexity dramatically. In addition, two coefficient selection strategies are proposed for both centrally controlled networks and distributed networks respectively. The theoretical analysis and simulation results prove that SLNC achieves a fairly low decoding complexity at a cost of rarely few extra transmissions. 相似文献