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本文提出一种多输入多输出(MIMO)天线系统中简单的扩展空时块编码(SSTBC)分集技术,采用沃尔什码来区分各天线发送数据子流。采用这种方法,在系统带宽一定时,不降低发送信息速率,同时接收机简单。不同天线的发送信息经过了所有收一发天线对之间的空间子信道,获得了所有路径的部分空间分集增益,仿真结果表明,这种增益的获得不受限于接收分集阶数,并且随发射天线的增加以一定的线性关系增加。 相似文献
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空时分集技术的最大优点在于在不增加带宽的情况下可以提高系统的可靠性,是目前移动通信的研究热点.常模算法是一种性能优良的码分多址(CDMA)盲多用户检测技术,能确保判决信号与实际传送信号之间的差错较小,误码率性能良好.文中提出将标准线性受限常模算法(LCCMA)与空时分组码(STBC)相结合,设计出一种收敛快、能够改善系统性能的基于2-空时分组码的多用户接收机. 相似文献
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无线信道中的电波传播 总被引:2,自引:0,他引:2
分析了信号在无线信道中传输时所经受的两种衰落,介绍了主要的无线传播模型,在此基础上提出了对抗衰落的措施。 相似文献
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It is widely believed that evolutionary dynamics of artificial self‐replicators realized in cellular automata (CA) are limited in diversity and adaptation. Contrary to this view, we show that complex genetic evolution may occur within simple CA. The evolving self‐replicating loops (“evoloops”) we investigate exhibit significant diversity in macro‐scale morphologies and mutational biases, undergoing nontrivial genetic adaptation by maximizing colony density and enhancing sustainability against other species. Nonmutable subsequences enable genetic operations that alter fitness differentials and promote long‐term evolutionary exploration. These results demonstrate a unique example of genetic evolution hierarchically emerging from local interactions between elements much smaller than individual replicators. © 2004 Wiley Periodicals, Inc. Complexity 10: 33–39, 2004 相似文献
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多版本软件通过设计相异性实现了软件容错。为了对这种方法进行研究,我们的课题实现了一个三版本软件系统,称之为SFTMP(SoftwareFault-TolerantMultiProcessor)。本文描述了SFTMP的硬件结构和软件执行支持环境,该环境包括同步、表决和监控功能、版本间的通讯及故障的恢复和重构。 相似文献
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Jerry W. Slootstra Wouter C. Puijk Gerard J. Ligtvoet Jan P. M. Langeveld Rob H. Meloen 《Molecular diversity》1996,1(2):87-96
Summary Two small random peptide libraries, one composed of 4550 dodecapeptides and one of 8000 tripeptides, were synthesized in newly developed credit-card format miniPEPSCAN cards (miniPEPSCAN libraries). Each peptide was synthesized in a discrete well (455 peptides/card). The two miniPEPSCAN libraries were screened with three different monoclonal antibodies (Mabs). Two other random peptide libraries, expressed on the wall of bacteria (recombinant libraries) and composed of 107 hexa- and octapeptides, were screened with the same three Mabs. The aim of this study was to compare the amino acid sequence of peptides selected from small and large pools of random peptides and, in this way, investigate the potential of small random peptide libraries. The screening of the two miniPEPSCAN libraries resulted in the identification of a surprisingly large number of antibody-binding peptides, while the screening of the large recombinant libraries, using the same Mabs, resulted in the identification of only a small number of peptides. The large number of peptides derived from the small random peptide libraries allowed the determination of consensus sequences. These consensus sequences could be related to small linear and nonlinear parts of the respective epitopes. The small number of peptides derived from the large random peptide libraries could only be related to linear epitopes that were previously mapped using small libraries of overlapping peptides covering the antigenic protein. Thus, with respect to the cost and speed of identifying peptides that resemble linear and nonlinear parts of epitopes, small diversity libraries based on synthetic peptides appear to be superior to large diversity libraries based on expression systems.Abbreviations ABTS
2,2-azino-di-3-ethylbenzthiazoline sulfonate
- EGF
epidermal growth factor
- Mab
monoclonal antibody
- ODccd
optical density obtained using CCD camera
- RAMPO
rabbit-antimouse peroxidase
- SDS
sodium dodecylsulfate
- TGEV
transmissible gastroenteritis virus 相似文献
9.
Brittain DE Gray BL Schreiber SL 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(17):5086-5093
A crossover in the ability of two distinct ruthenium-based metathesis pre-catalysts to effect the synthesis of dialkenylboronic esters in solution and on the solid-phase was observed. Specifically, while the Grubbs 2nd generation pre-catalyst 3 affords a greater degree of conversion to product than the Hoveyda-Grubbs pre-catalyst 2 in a solution-phase enyne-metathesis reaction, this trend is reversed in the solid-phase variant. Systematic investigation showed this trend to be general, regardless of variations in the homoallylic alcohol and alkynylboronic ester components of the reaction, as well as in the type of solid support employed. Experiments to determine a mechanistic hypothesis for this trend highlighted the significance of the ruthenium remaining bound to the substrate after metathetic rearrangement and found the presence of phosphine ligand to be detrimental to the success of the solid-phase reaction. Therefore, these results suggest an expanded role for phosphine-free pre-catalysts, such as 2, in challenging solid-phase metathesis reactions. 相似文献
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瑞利衰落信道采用组合发射机SC/接收机 MRC的MQAM性能分析 总被引:4,自引:0,他引:4
日益增长的无线业务需求要求提高衰落信道上无线通信的频谱利用率.本文研究一种使用组合发射机SC/接收机MRC(SC/MRC)的MQAM方案,推导其在平坦瑞利衰落信道上的误符号率,分析无线信道时变特性对系统性能的影响.数值计算结果表明该组合空间分集方案可以通过调整发射天线和接收天线的数目来获得比传统接收机分集接收更大的分集增益. 相似文献