共查询到20条相似文献,搜索用时 796 毫秒
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在基于“信道容量规则”的多级编码系统中采用交织技术与迭代多级译码相结合的方法,进一步提高其在Rayle曲衰落信道中的系统性能。 相似文献
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文中提出了一种简化的多级译码方法。这种译码方法能够在不损害编码系统传输性能的情况下有效地减少译码器的运算量,从而减少译码时延,使高速译码的实时实现成为可能。 相似文献
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多级安全机制是指能在计算机系统中处理多个不同敏感级别信息的方法,传统的多级安全机制一般需要可信操作系统支持,但这不仅在实现上难度大,而且还会导致应用兼容性问题和难以克服的安全隐通道问题。这里提出一种基于虚拟化技术的多级安全机制结构,它通过强安全隔离机制避免不同安全级别信息之间的交叉污染和隐通道问题,通过无缝支持商用操作系统和既有应用的设计机制降低多级安全系统的应用难度和实现成本。基于虚拟化技术的多级安全机制还通过采用显式安全标记和隐式安全标记相结合的方法,简化了系统的安全管理。 相似文献
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针对现有的多级安全访问控制模型过于复杂而不利于实际部署以及在密钥管理中存在的漏洞,文章在改良密钥生成算法,紧密结合可信计算技术支持的信任验证机制,提出了一种新的多级安全访问控制方案。与传统的方案相比,新方案不仅更加简洁、灵活,便于与原有系统进行整合,同时,克服了密钥管理上的漏洞。 相似文献
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Te-Ming Tu Chin-Hsing Chen Jiunn-Lin Wu Chein-I Chang 《Geoscience and Remote Sensing, IEEE Transactions on》1998,36(1):182-191
Classification for high-dimensional remotely sensed data generally requires a large set of data samples and enormous processing time, particularly for hyperspectral image data. In this paper, the authors present a fast two-stage classification method composed of a band selection (BS) algorithm with feature extraction/selection (FSE) followed by a recursive maximum likelihood classifier (MLC). The first stage is to develop a BS algorithm coupled with FSE for data dimensionality reduction. The second stage is to design a fast recursive MLC (RMLC) so as to achieve computational efficiency. The experimental results show that the proposed recursive MLC, in conjunction with BS and FSE, reduces computing time significantly by a factor ranging from 30 to 145, as compared to the conventional MLC 相似文献
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基于8PSK的MLC-STBC在瑞利衰落信道中的性能 总被引:1,自引:0,他引:1
文章提出了在瑞利信道中,8PSK调制模式下多级编码空时分组编码级联的MLC-STBC方案,并在系统码率为2.032bit/s、发射天线为2、接收天线数目为1的条件下,分别对多级编码和MLC-STBC级联编码进行了仿真。仿真结果表明,基于8PSK,在瑞利衰落下利用旋转距离度量规则选择分量码码率的MLC-STBC系统,能获得比较理想的系统增益。 相似文献
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Lampe L.H.-J. Schober R. Fischer R.F.H. 《Wireless Communications, IEEE Transactions on》2004,3(1):203-208
The application of powerful coding for transmission over multiple-input/multiple-output channels is discussed. The authors emphasize that as an immediate consequence of the mutual information chain rule, multilevel coding (MLC) constitutes the optimum coded modulation scheme. On the other hand, simple bit-interleaved coded modulation (BICM) is only a convenient alternative for the case of two transmit and one receive antennas when combined with orthogonal space-time block codes. Starting from MLC, the authors further propose a hybrid coded modulation scheme, which favorably combines the advantages of MLC and BICM. 相似文献
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Bedeschi F. Fackenthal R. Resta C. Donze E.M. Jagasivamani M. Buda E.C. Pellizzer F. Chow D.W. Cabrini A. Calvi G. Faravelli R. Fantini A. Torelli G. Mills D. Gastaldi R. Casagrande G. 《Solid-State Circuits, IEEE Journal of》2009,44(1):217-227
In this paper, a 90-nm 128-Mcell non-volatile memory based on phase-change Ge2-Sb2-TeB alloy is presented. Memory cells are bipolar selected, and are based on a /xtrench architecture. Experimental investigation on multi-level cell (MLC) storage is addressed exploiting the chip MLC capability. To this end, a programming algorithm suitable for 2 bit/cell storage achieving tightly placed inner states (in terms of cell current or resistance) is proposed. Measurements showed the possibility of placing the required distinct cell current distributions, thus demonstrating the feasibility of the MLC phase-change memory (PCM) storage concept. Endurance tests were also carried out. Cumulative distribu tions after 2-bit/cell programming before cycling and after 100 k program cycles followed by 1 h/150 degC bake are presented. Experimental results on MLC endurance are also provided from a 180-nm 8-Mb PCM demonstrator with the same mutrench cell structure. 相似文献
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Hui Ding Min Zhang Byrav Ramamurthy Zhuo Liu Shanguo Huang Xue Chen 《Photonic Network Communications》2014,28(3):295-305
Elastic optical network is introduced as a promising technology to provide multi-bitrate-friendly data transmission in the optical layer. Elastic optical networks are based on flexible modulation format conversion, which can make more efficient use of spectrum resources than current fix-grid WDM networks. In this paper, we define the routing, modulation level and spectrum resource allocation (RMLSA) problem and then propose two novel dynamic modulation level conversion (MLC) enabled RMLSA algorithms. Numerical simulations are conducted to compare the performance of the path modulation level conversion (Path-MLC) and link modulation level conversion (Link-MLC) with different MLC thresholds with K-shortest paths RSA in terms of blocking rate, occupied spectrum and the number of MLCs across two topologies. The results verify that the Link-MLC with unlimited MLC achieves the lowest blocking rate and moderate spectrum utilization at the expense of intermediate node modulation conversions in two topologies. Smaller MLC threshold has higher blocking rate and occupied less spectrum resource. The results also suggest that the Path-MLC approach is more resource efficient than the Link-MLC with relatively higher blocking rate, and this method maybe more preferable in the networks with tight budget and/or energy constraints. 相似文献
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Taehee Cho Yeong-Taek Lee Eun-Cheol Kim Jin-Wook Lee Sunmi Choi Seungjae Lee Dong-Hwan Kim Wook-Ghee Han Young-Ho Lim Jae-Duk Lee Jung-Dal Choi Kang-Deog Suh 《Solid-State Circuits, IEEE Journal of》2001,36(11):1700-1706
A 116.7-mm2 NAND flash memory having two modes, 1-Gb multilevel program cell (MLC) and high-performance 512-Mb single-level program cell (SLC) modes, is fabricated with a 0.15-μm CMOS technology. Utilizing simultaneous operation of four independent banks, the device achieves 1.6 and 6.9 MB/s program throughputs for MLC and SLC modes, respectively. The two-step bitline setup scheme suppresses the peak current below 60 mA. The wordline ramping technique avoids program disturbance. The SLC mode uses the 0.5-V incremental step pulse and self-boosting program inhibit scheme to achieve high program performance, and the MLC mode uses 0.15-V incremental step pulse and local self-boosting program inhibit scheme to tightly control the cell threshold voltage Vth distributions. With the small wordline and bitline pitches of 0.3-μm and 0.36-μm, respectively, the cell Vth shift due to the floating gate coupling is about 0.2 V. The read margins between adjacent two program states are optimized resulting in the nonuniform cell Vth distribution for MLC mode 相似文献
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The nondestructive detection of defects in multilayer ceramic capacitors (MLCs) in-surface mount printed circuit board assemblies has been demonstrated by using an improved digital speckle correlation method (DSCM). The internal cracks in MLCs that contribute to the thermal displacements on the MLC surface after dc electrical loading may be uniquely identified using this improved DSCM combined with double lens optical arrangement. However, it is found that Joule heating of the MLC sample takes time, and therefore the thermal displacements on the MLC surface are not obvious at the beginning of the dc electrical loading. In order to shorten the detection time and increase the resolution of the DSCM, a wavelet packet noise reduction process is introduced into the DSCM technique. This new algorithm is used to reduce the background noise in the signal so as to improve the accuracy of detection of defect locations and reduce the detection time. By introducing wavelet packet noise reduction processing, the DSCM is found to be more sensitive to and faster at detecting defects in MLC samples. Furthermore, the DSCM with wavelet packet noise reduction process can cope with the problems of edge effect, rough and warped surface, which are the limitations of the scanning acoustic microscope (SAM) 相似文献
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By introducing a mobility anchor point (MAP), Hierarchical Mobile IPv6 (HMIPv6) reduces the signaling overhead and handoff
latency associated with Mobile IPv6. In this paper, we propose a mobility-based load control (MLC) scheme, which mitigates
the burden of the MAP in fully distributed and adaptive manners. The MLC scheme combines two algorithms: a threshold-based
admission control algorithm and a session-to-mobility ratio (SMR)-based replacement algorithm. The threshold-based admission
control algorithm gives higher priority to ongoing mobile nodes (MNs) than new MNs, by blocking new MNs when the number of
MNs being serviced by the MAP is greater than a predetermined threshold. On the other hand, the SMR-based replacement algorithm
achieves efficient MAP load distribution by considering MNs’ traffic and mobility patterns. We analyze the MLC scheme using
the continuous time Markov chain in terms of the new MN blocking probability, ongoing MN dropping probability, and binding
update cost. Also, the MAP processing latency is evaluated based on the M/G/1 queueing model. Analytical and simulation results
demonstrate that the MLC scheme outperforms other schemes and thus it is a viable solution for scalable HMIPv6 networks. 相似文献