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抗信道快变的酉空时星座设计  [PDF]
孙洁挺,沙济彰
华东理工大学学报 , 2005,
Abstract: 分析了移动台以不同大小速率移动时,信道衰落系数在同一分组长度内的快变性。通过计算机仿真分析发现:酉空时码的误码率随着信道衰落系数自相关函数的减小而恶化,且随分组长度增大而加深恶化。在系统化酉空时星座设计方法的基础上,提出了一种抗信道快变的酉空时星座设计方案。仿真结果表明:该方案可有效地缓解由于信道快变而引起的误码率恶化问题。
在grassmann流形上构造非相干酉空时码  [PDF]
符达伟,彭立,王利娇,彭秋平
通信学报 , 2013,
Abstract: ?研究基于grassmann流形的非相干酉空时星座图的设计方法。首先定义了非相干空时码在流形上的酉矩阵框架结构;然后在此框架约束下,将已有的grassmann流形上最优包络分布的最小frobenius弦距离作为阈值,通过设置合适的步长来改变酉矩阵中各元素的幅值和相位,在流形上搜索最小frobenius弦距离大于阈值的点,搜索到事先设定的星座图点数,即构成酉空时星座图。数值仿真结果表明本框架结构非相干grassmannian酉空时码的性能均优于现有的其他形式非相干酉空时码的性能。
一种联合酉空时星座图的分类解调算法  [PDF]
韩东升,杨维,谢映海
电子学报 , 2015, DOI: 10.3969/j.issn.0372-2112.2015.04.015
Abstract: 本文提出了一种基于排列法和旋转法联合生成的酉空时星座图设计新方法,该方法可为酉空时信号提供性能较好的星座图.同时,针对这种联合星座图给出了一种新型的分类解调算法,该算法可以以很低的错误概率识别出发射信号的类型,从而通过分类来缩小最大似然原则下的星座点搜索范围,在提高误码率性能的同时也降低了复杂度.理论分析和仿真结果都表明,与一些单一方法生成的星座图相比,本文所提出新型联合星座图在误比特率性能和解调算法复杂度上都有较大的改善.
基于正交空时分组码的酉空时码设计  [PDF]
郭永亮,朱世华,张国梅
电子学报 , 2006,
Abstract: 提出了一种基于正交空时分组码构造酉空时码的方案,证明了所设计的酉空时码可以获得满分集.同原有方案相比,所提方案的优点是其码率较高,缺点是解码复杂度较原方案高.针对该缺点,提出了一种次优解码算法,该算法的复杂度同原方案几乎相同.Monte-Carlo仿真实验表明,在相同的频谱效率下,对同一误码率本文方案所需信噪比比原方案低5dB;同时,对同一误码率本文的次优解码算法同最优解码算法相比信噪比损失约1dB.
一种基于检测转发方式的酉空时协作分集技术  [PDF]
郭希蕊,雷维嘉,谢显中
重庆邮电大学学报(自然科学版) , 2008,
Abstract: 对一种基于检测转发方式的酉空时协作分集技术进行了研究,该技术可以在发送端和接收端都不知道信道信息的情况下使数据可靠地传输。在该协作分集技术下,通过对2个用户协作系统进行仿真分析,结果表明,其误码率性能与每个用户的信道和用户间的信道相关。
一种高效的酉空时信号译码算法  [PDF]
北京工业大学学报 , 2011,
Abstract: 针对系统产生的酉空时码,提出一种高效的译码算法.接收机计算连续产生的L/2+W(L为星座点数目,W为窗长)个星座点与接收信号的内积范数,将L/2+W个内积范数每隔W的范数值相加,得到L/2个和值;从所得到的和值中搜索极大值,通过该极大值的位置可以将搜索范围降低至3个星座点,最后比较这3个星座点便可搜索到全局最优解.所提算法可以有效地降低最大似然(maximumlikelihood,ML)算法的搜索空间,窗长W越小搜索空间降低越多.计算机仿真结果表明,针对给定的星座点,当窗长W为4时,所提算法将ML算法的搜索空间降低一半,而信噪比损失只有2dB左右.
一种性能更优的差分酉空时码正交旋转信号星座  [PDF]
李君,曹海燕,韦岗
电子学报 , 2005,
Abstract: 由于差分酉空时码信号星座点之间的分集乘积是影响系统的重要因素.本文利用代数理论构造出一种正交旋转的差分酉空时码的信号星座集,使得原循环群星座成为新正交旋转星座的一个搜索子集,以扩大信号星座点之间的分集乘积,其误码率性能将比原循环群星座差分酉空时码有2dB多的增益.
空间相关信道下酉空时系统的最大似然多符号差分检测算法  [PDF]
蓝兴,马东堂,魏急波
电子学报 , 2009,
Abstract: 传统的酉空时系统,通常假设信道衰落系数之间相互独立,这个条件在实际系统中却很难满足,天线之间的空间相关性造成系统性能恶化.针对该问题,本文提出了空间相关信道下酉统空时系的最大似然多符号差分检测算法.本算法只需获取每个观测窗口的第一个符号,以该符号为导频符号,其传输效率渐近为1,并且不要求系统具有反馈信道,算法中最大似然解的快速搜索可以通过球形译码来实现.计算机仿真结果表明:本算法可以在不明显增加开销的情况下,有效的提高空间相关信道下酉空时系统的误码率性能.
算子的酉扩张  [PDF]
严绍宗
科学通报 , 1980,
Abstract: 本文中讨论Hilbert空间或不定尺度空间上算子的酉扩张问题。
The Feasibility and Acceptability of LISTEN for Loneliness  [PDF]
Laurie A. Theeke, Jennifer A. Mallow, Emily R. Barnes, Elliott Theeke
Open Journal of Nursing (OJN) , 2015, DOI: 10.4236/ojn.2015.55045
Abstract: Purpose: The purpose of this paper is to present the initial feasibility and acceptability of LISTEN (Loneliness Intervention using Story Theory to Enhance Nursing-sensitive outcomes), a new intervention for loneliness. Loneliness is a significant stressor and known contributor to multiple chronic health conditions in varied populations. In addition, loneliness is reported as predictive of functional decline and mortality in large samples of older adults from multiple cultures. Currently, there are no standard therapies recommended as effective treatments for loneliness. The paucity of interventions has limited the ability of healthcare providers to translate what we know about the problem of loneliness to active planning of clinical care that results in diminished loneliness. LISTEN was developed using the process for complex intervention development suggested by the Medical Research Council (MRC) [1] [2]. Methods: Feasibility and acceptability of LISTEN were evaluated as the first objective of a longitudinal randomized trial which was set in a university based family medicine center in a rural southeastern community in Appalachia. Twenty-seven older adults [(24 women and 3 men, mean age: 75 (SD 7.50)] who were lonely, community-dwelling, and experiencing chronic illness, participated. Feasibility was evaluated by tracking recruitment efforts, enrollment, attendance to intervention sessions, attrition, and with feedback evaluations from study personnel. Acceptability was assessed using quantitative and qualitative evaluation data from participants. Results: LISTEN was evaluated as feasible to deliver with no attrition and near perfect attendance. Participants ranked LISTEN as highly acceptable for diminishing loneliness with participants requesting a continuation of the program or development of additional sessions. Conclusions: LISTEN is feasible to deliver in a primary healthcare setting and has the potential to diminish loneliness which could result in improvement of the long-term negative known sequelae of loneliness such as hypertension, depression, functional decline, and mortality. Feedback from study participants is being used to inform future trials of LISTEN with consideration for developing additional sessions. Longitudinal randomized trials are needed in varied populations to assess long-term health and healthcare system benefits of diminishing loneliness, and to assess the potential scalability of LISTEN as a reimbursable treatment for loneliness.
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