共查询到17条相似文献,搜索用时 323 毫秒
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为提高定时捕获的正确捕获概率并降低漏检概率,提出一种基于分布式天线协同感知的定时捕获方法。该方法针对线形小区的平坦瑞利衰落信道场景,利用两根分布式接收天线接收来自单天线移动台的发射信号;根据中心处理器处的协同感知,确保各分布式接收天线的预定虚警概率,并为门限检测推导协同处理门限;各天线根据门限检测进行分布式天线系统的最大似然定时捕获。仿真结果表明,无论移动台处于线形小区的哪个位置,提出方法在不增加预定虚警概率的情况下,均能改善各分布式天线的正确捕获概率和漏检概率。 相似文献
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不精确的定时捕获造成分布式天线系统性能下降,为提高定时捕获时的正确捕获概率,提出分布式天线协同校验的定时捕获方法。在线形小区的平坦瑞利信道中考虑有两根分布式接收天线,根据时延差先验信息,建立协同校验的限制条件;然后,各分布式天线根据门限检测方法进行定时捕获;为去除部分定时捕获错误,各分布式天线在构建的限制条件下进行协同校验与校验后处理。分析与仿真结果表明,提出方法能有效地提高各分布式天线定时捕获时的正确捕获概率。 相似文献
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一种低复杂度的线性离散码发射天线选择技术 总被引:1,自引:0,他引:1
为了充分利用多天线系统的性能增益,通过研究集中式MIMO(Multiple input multiple output)系统中最大化最小后验SNR (Signal to noise ratio)准则的局限性,提出了一种低复杂度的基于线性离散码的发射天线选择方案.然后分析了分布式MIMO系统中,移动台距不同基站间不同的大尺度衰落对信道特征值的影响,证明了所提天线选择准则在分布式系统中的有效性.仿真结果表明,在准静态信道环境下,所提天线选择准则具有比最大化最小后验SNR准则更好的性能,并且复杂度更低. 相似文献
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位置管理是个人通信网络的一个挑战性问题,用于跟踪移动台,有位置更新与寻呼两个基本操作.在一些知名的位置管理策略中,基于移动的位置管理策略(movement-based location management scheme)具有简单易行的特点:各移动台只需记住所越过的小区边界次数,一旦这个数超过事先定义的一个整数--移动门槛,就进行位置更新操作.在移动台的呼入符合泊松分布,移动台在各个小区的逗留时间符合指数分布的条件下,推导了基于移动的位置管理策略中移动台移动距离的概率分布及平均距离公式,并基于这些概率分布给出了最优顺序寻呼算法.最后,给出数值分析结果,以说明所给出的寻呼策略比其他已有策略更优. 相似文献
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目前波束成型和速率分配算法大多考虑集中式天线下的总功率受限和总速率最优,本文针对多小区多用户基站协作系统,考虑分布式天线的特点和用户公平性的要求,提出一种在各发送天线功率受限下的QAM速率分配算法,最大化最小用户速率,并迭代调整各子流的功率,为用户的每个子流分配一种QAM速率,仿真结果表明,在满足目标误码率要求下,该算法能够保持最优平均速率,提高最小用户速率,保证用户间的公平性. 相似文献
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基于对数似然比(LLR)的天线分集是误码性能优于传统基于信噪比(SNR)天线分集的一种新技术,并降低了系统的实现复杂性和成本。为此对基于LLR的发射天线选择新技术进行了研究,推导了多输入多输出(MIMO)Nakagami衰落信道上基于符号对数似然比(SLLR)和比特对数似然比(BLLR)的发射天线选择准则,并对M进制调制系统进行仿真研究。结果表明,基于BLLR准则的MIMO系统误比特率最小;采用SLLR准则和BLLR准则时,在保持发射端和接收端的天线总数不变的条件下,分集数量级大的系统误比特率性能好;数量级相等时,接收天线较多的系统性能较优。 相似文献
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分布式MIMO系统的天线数目与点对点MIMO相比进一步增多,性能优越的经典天线选择算法难以应用其中。针对这一问题,在分布式架构的基础上提出一种基于逐增端口选择的改进型逐减天线选择算法。该算法通过设定上限的动态端口选择缩小待选天线范围,进而利用贪心策略,逐步去除对信道容量贡献最小的天线。仿真结果表明,该算法的容量性能逼近穷举算法,且复杂度大幅降低,在强相关信道下表现出良好的适应性。 相似文献
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To solve complex antenna design problems, this article proposes a hybrid differential evolution algorithm (DE). The proposed method combines the DE with the simplified quadratic interpolation (SQI) to optimize the performance of the antenna. The DE is the global optimizer, and the SQI is used to fine tune. The hybrid DE is demonstrated on optimizing designing Yagi‐Uda antennas and wideband patch antennas. Numerical results confirm that the proposed method is superior to or at least competitive with the original DE and other evolutionary algorithms in terms of convergence speed and solution quality. © 2009 Wiley Periodicals, Inc. Int J RF and Microwave CAE 2010. 相似文献
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Synthesis of circular antenna arrays to have individually arbitrary sidelobe levels, is investigated. Circular arrays are synthesized by applying a transformation to previously designed linear arrays. The antennas of the circular arrays are considered either isotropic or directive. The synthesized patterns are steerable without any distortion. Some examples are brought to verify the effectiveness of the proposed procedure for both isotropic and directive antennas. 相似文献
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In this article, an effective method to reduce the mutual coupling between the antipodal tapered slot antenna (ATSA) array is proposed. This method is mainly implemented by loading a set of decoupling structures (DS) perpendicular to the dielectric substrate between two antenna elements. The proposed DS can provide transmission forbidden band which can effectively prevent leaked electromagnetic waves. DS can operate in most frequency bands within 4 to 17.5 GHz. It can enhance about 23 dB isolation between the ATSA array without affecting bandwidth and radiation characteristics. The proposed ATSA arrays are fabricated and tested. The measured results can verify its excellent properties. The proposed broadband decoupling method is a suitable candidate for restrain mutual coupling of ultra‐wideband planar end‐fire antennas. This design sheds new light on broadband decoupling. 相似文献
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Recent interest in the application of metamaterials to antenna design has shown some promise in terms of improving the performance of disadvantaged antennas. In this article, we shall consider the design of a linear insulated antenna with a metamaterial coating operating in a lossy surrounding medium. Performance shall be examined for two different embodiments of this antenna using a genetic algorithm as the design tool, and shall address designs based on maximum antenna bandwidth, gain, and gain‐bandwidth product. Practical implementation of such antennas shall also be discussed and some experimental data presented. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. 相似文献
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This article presents the designs of dual‐polarized dual wideband textile‐based two and four elements multiple‐input multiple‐output (MIMO) antennas for WLAN (IEEE 802.11a/b/g/c/n) and WiMAX (IEEE 802.16d) applications. These MIMO antennas cover the frequency spectra from 1.5 to 3.8 GHz (87% bandwidth) and 4.1 to 6.1 GHz (40% bandwidth). The characterization of the textile jeans substrate is determined experimentally using a vector network analyzer and dielectric assessment kit. These antennas provide near about 70% radiation efficiency with around 4 dBi peak gain in desired frequency ranges. The diversity performance is improved noticeably by printing meandered line structures on both planes. The proposed MIMO structure has a very low envelop correlation coefficient (ECC) <0.1 and high diversity gain (DG) >9.9. The Medium effective gain (MEG) also lies within a satisfactory value of ±3 dB. The two elements MIMO Antennas provide linear polarization at all desired frequency band while the four‐element antenna provides circular polarization at 2.4 GHz and linear polarization at 5.2 and 5.8 GHz application bands. The antenna also depicts good performance in wearable condition with safe specific absorption rate < 1.6 W/kg in all desired frequencies. 相似文献