随着大数据应用的发展,保障数据无中断传输的需求日益增强.针对单点或单链路失效的情况,现有的保障数据无中断传输方法存在主/备份路径的数据传输性能较低、抵御多节点/边失效能力不强等问题.为解决以上问题,提出一种可保障数据无中断...随着大数据应用的发展,保障数据无中断传输的需求日益增强.针对单点或单链路失效的情况,现有的保障数据无中断传输方法存在主/备份路径的数据传输性能较低、抵御多节点/边失效能力不强等问题.为解决以上问题,提出一种可保障数据无中断传输的按边序选环的冗余树算法CSES(circle selecting by edge sorting based redundant tree algorithm for uninterrupted data delivery),可用于构建数据传输性能优化的主/备份路径,并使数据传输具有较强的抵御多节点/边失效的能力.该算法首先根据网络拓扑构建以数据源为根节点的最小传输树,以最小化主传输路径上的转发跳数;其次,为了减少备份路径的转发跳数并提高数据传输抵御多节点/边失效的能力,对拓扑中不在最小传输树上的边进行排序,将树上根节点到边上2个端点的路径上节点数量之和较小的边排在前列.随后按序将边添加到最小传输树上以构建冗余环,并基于冗余环生成冗余枝添加到最小传输树上,最终形成以数据源为根节点的冗余树.实验结果表明,相比于其他冗余树算法,基于CSES算法构建的冗余树所生成的主/备份路径的转发跳数更少且抵御多节点/边失效的能力更强.展开更多
To overcome some drawbacks of Viterbi algorithm （VA）, such as exponential growing complexity of decoding, and its poor performance under bad channel conditions, some available known information must be used as cons...To overcome some drawbacks of Viterbi algorithm （VA）, such as exponential growing complexity of decoding, and its poor performance under bad channel conditions, some available known information must be used as constrained condition and apriori knowledge for decoding. A new constrained VA is proposed by adding con- straint bits directly for conventional codec. Compared with the conventional VA, under the bad channel condi- tion, the proposed scheme can improve the peak signal to noise ratio （PSNR） of the decoding image 2--10 dB by changing the number of constrained bits. Experimental results show that it is an efficient error-controlling way for the transmission of set partitioning in hierarchical trees （SPIHT） coded image.展开更多
Many efforts have been made to develop time division multiple access （TDMA） slots allocation in a multi-hop converge-cast wireless sensor network （WSN）, however, most of them either use complex algorithm or concer...Many efforts have been made to develop time division multiple access （TDMA） slots allocation in a multi-hop converge-cast wireless sensor network （WSN）, however, most of them either use complex algorithm or concern frames only without simultaneous transmission in a single slot. In this paper, we present a timeslot assignment scheme for cluster-tree-based TDMA WSN, co：＇ering three frequently used working modes in practical applications. The shortest frame formed can guarantee real-time conununication and is also facilitated for message and slot integration, since timeslots allocated to a single node are continuous. During allocation processes, the algorithms are distributed and light-weighted. The experiment resulted from a WSN prototype system shows that our scheme can achieve a good reliability.展开更多
According to the sequential maximum a posteriori probability (SMAP) rule, this paper proposes a novel multi-scale Bayesian texture segmentation algorithm based on the wavelet domain Hidden Markov Tree (HMT) model. In ...According to the sequential maximum a posteriori probability (SMAP) rule, this paper proposes a novel multi-scale Bayesian texture segmentation algorithm based on the wavelet domain Hidden Markov Tree (HMT) model. In the proposed scheme, interscale label transition probability is directly defined and resoled by an EM algorithm. In order to smooth out the variations in the homogeneous regions, intrascale context information is considered. A Gaussian mixture model (GMM) in the redundant wavelet domain is also exploited to formulate the pixel-level statistical features of texture pattern so as to avoid the influence of the variance of pixel brightness. The performance of the proposed method is compared with the state-of-the-art HMTSeg method and evaluated by the experiment results.展开更多
文摘随着大数据应用的发展,保障数据无中断传输的需求日益增强.针对单点或单链路失效的情况,现有的保障数据无中断传输方法存在主/备份路径的数据传输性能较低、抵御多节点/边失效能力不强等问题.为解决以上问题,提出一种可保障数据无中断传输的按边序选环的冗余树算法CSES(circle selecting by edge sorting based redundant tree algorithm for uninterrupted data delivery),可用于构建数据传输性能优化的主/备份路径,并使数据传输具有较强的抵御多节点/边失效的能力.该算法首先根据网络拓扑构建以数据源为根节点的最小传输树,以最小化主传输路径上的转发跳数;其次,为了减少备份路径的转发跳数并提高数据传输抵御多节点/边失效的能力,对拓扑中不在最小传输树上的边进行排序,将树上根节点到边上2个端点的路径上节点数量之和较小的边排在前列.随后按序将边添加到最小传输树上以构建冗余环,并基于冗余环生成冗余枝添加到最小传输树上,最终形成以数据源为根节点的冗余树.实验结果表明,相比于其他冗余树算法,基于CSES算法构建的冗余树所生成的主/备份路径的转发跳数更少且抵御多节点/边失效的能力更强.
文摘To overcome some drawbacks of Viterbi algorithm （VA）, such as exponential growing complexity of decoding, and its poor performance under bad channel conditions, some available known information must be used as constrained condition and apriori knowledge for decoding. A new constrained VA is proposed by adding con- straint bits directly for conventional codec. Compared with the conventional VA, under the bad channel condi- tion, the proposed scheme can improve the peak signal to noise ratio （PSNR） of the decoding image 2--10 dB by changing the number of constrained bits. Experimental results show that it is an efficient error-controlling way for the transmission of set partitioning in hierarchical trees （SPIHT） coded image.
基金Supported by the National High Technology Research and Development Programme of China ( No. 2006AA040302 2007AA041201 +1 种基金 2007AA041301 )the National Creative Research Groups Science Foundation of China (No. 60721062)
文摘Many efforts have been made to develop time division multiple access （TDMA） slots allocation in a multi-hop converge-cast wireless sensor network （WSN）, however, most of them either use complex algorithm or concern frames only without simultaneous transmission in a single slot. In this paper, we present a timeslot assignment scheme for cluster-tree-based TDMA WSN, co：＇ering three frequently used working modes in practical applications. The shortest frame formed can guarantee real-time conununication and is also facilitated for message and slot integration, since timeslots allocated to a single node are continuous. During allocation processes, the algorithms are distributed and light-weighted. The experiment resulted from a WSN prototype system shows that our scheme can achieve a good reliability.
文摘According to the sequential maximum a posteriori probability (SMAP) rule, this paper proposes a novel multi-scale Bayesian texture segmentation algorithm based on the wavelet domain Hidden Markov Tree (HMT) model. In the proposed scheme, interscale label transition probability is directly defined and resoled by an EM algorithm. In order to smooth out the variations in the homogeneous regions, intrascale context information is considered. A Gaussian mixture model (GMM) in the redundant wavelet domain is also exploited to formulate the pixel-level statistical features of texture pattern so as to avoid the influence of the variance of pixel brightness. The performance of the proposed method is compared with the state-of-the-art HMTSeg method and evaluated by the experiment results.
