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基于OFDM下行系统,提出并比较了自适应天线阵列和分组调度算法结合的三种方式:(1)分组调度选择用户,自适应天线服务用户;(2)自适应天线参与选择用户,并且服务用户;(3)空分方式选择用户,自适应天线服务用户.仿真结果显示自适应天线阵列可以明显提高小区吞吐率等指标,并且(2)和(3)的性能优于(1). 相似文献
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OFDM系统智能天线设计中的波束综合算法 总被引:1,自引:0,他引:1
基于自适应天线阵列理论。提出了一种新的可以应用于任意类型天线阵列的波束综合算法。根据与给定的参考波束的误差。引入虚拟干扰的概念,对目标波束图形状进行调整。应用本文提出的新算法,在主瓣和旁瓣位置都可以对波束进行有效的调节。最终获得阵列的最优权矢量,能够最小化目标波束图与参考波束图间的差异。理论分析与仿真结果表明与现有的同类算法相比,本算法能更有效地获得与参考波束基本相符的波束。在设计应用于OFDM智能天线系统时,通过对不同子载波频率上信号进行单独处理,利用该算法.进行波束综合,能够在整个有效频段,所有子载波上获得基本一致的阵列输出。 相似文献
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简要叙述了移动通信的方式和特点,移动通信的设备和应用。着重介绍了第三代移动通信对天线智能化的要求和目前已经开发并用于移动通信系统的几种电控阵列天线。 相似文献
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提出一种基于阵列天线的正交频分多址(OFDMA)上行链路载频偏闭式盲估计方法,基站端配备阵列天线,该方法基于各天线阵元的空域快拍之间存在的旋转不变性,结合子空间平滑的思想,可在低运算复杂度的条件下,利用波达方向矩阵法得到信号空间的原始基底,由此可进一步同时获得各子载波对应用户的波达方向(DOA)与载频偏的闭式估计.该方法支持任意子载波分配方案以及满负载系统,并且可根据当前系统负载动态调整估计复杂度.理论分析和仿真结果验证了本文方法的有效性. 相似文献
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分析了智能天线自适应算法的基本原理,针对常用算法运算量大和测向精度有限等问题,在接收机的输出端引入阵列导向矢量信号,利用方向性因子和协方差矩阵的特殊性质,通过多次迭代运算得出区间内的信干噪比曲线。通过对八元直线型智能天线阵列的HFSS仿真实验表明,两组信干噪比曲线峰值均对应期望信号方向,峰值信干噪比大于30 dB,算法抗干扰性能良好。八元阵列天线的最大增益约为18 dB,通带内驻波比小于15,反射系数小于-25 dB,天线系统波束搜索性能良好,而且可以实现远距离传输。 相似文献
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OFDM is recognized to be one of the best transmission techniques for wideband wireless communication systems. However, it
exhibits two main drawbacks: its large amplitude fluctuation and its sensitivity to phase noise. Here we consider the phase
noise impairments, taking care of the phase noise spectrum, which diverges form the classical Wiener model as the carrier
frequency increases. Moreover, we show that the phase noise distortion can be decomposed in two terms, one dependent on the
symbol under detection and the other dependent on the symbols of adjacent subcarriers, so that the performance degradation
depends on both the constellation used in each subcarrier and the phase noise spectrum. As a consequence of this new results,
the penalty due to phase noise expressed in terms of the average signal/noise plus interference ratio is not applicable in
the case of modulations with non-constant amplitude constellations, such as 16- or 64-QAM. The method proposed here achieves
a good accuracy, while keeping a low computational complexity, and it is confirmed by simulations.
Roberto Corvaja was born in Padova (Italy) in 1967. He graduated at the Universisty of Padova in Electronic Enginering on 1990 and got his
Ph.D. at the Univeristy of Padova in 1994. Since 1994 he is with the Dipartimento di Elettronica e Informatica of the University
of Padova as a researcher and assistant professor on digital communications. Between 1994 and 1995 he spent 8 months at Hewlett-Packard
Laboratories, Bristol (UK), working on equalization for a DECT receiver. His research activity in the past has regarded optical
fibre communications systems and now is devoted to wireless communication systems.
Silvano Pupolin was born in Venice, Italy, on February 17, 1947. He received the Laurea degree in Electronic Engineering from the University
of Padova, Padova, Italy, in 1970. Since then he joined the Dipartimento di Elettronica e Informatica of the Universita' di
Padova, where he currently is a Full Professor of Electrical Communications. He spent the summer 1985 at AT&T Bell Laboratories
on leave from Padova, doing research on digital radio systems. He has been actively engaged in researches on digital communication
systems since 1970. The topics covered has been: performance of baseband digital comunication systems, line encoding for spectral
shaping, timing extraction, direct detection fiber optic system, spread spectrum communication systems, digital radio communications,
with emphasis to the adaptive linearization of the High-Power-Amplifier. Actually, he is actively engaged in researches on
digital radio, spread s pectrum systems, packet radio networks, personal communication systems and Cellular access to broadband
systems for interactive communications. He is also National Project leader for a research on Personal Communication Systems.
Dr. Pupolin is a Senior Member of IEEE and Member of AEI. 相似文献
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提出了一种正交频分复用(OFDM)系统的频率同步方案。该方案包含一个细同步算法和一个粗同步算法。细同步算法是对MOOSE算法的改进,使其频率捕获范围扩大一倍;粗同步算法通过对特殊的长训练序列进行频域相关运算,来估计大范围的频率偏移,它与改进的细同步算法相结合,能够纠正达到半个系统带宽的频偏。仿真表明这是一种准确而可靠的频率同步方案。 相似文献
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本文提出了一种正交频分复用(OFDM)系统的频率同步方案。该方案包含一个细同步算法和一个粗同步算法。细同步算法是对MOOSE算法的改进,使其频率捕获范围扩大一倍;粗同步算法通过对特殊的长训练序列进行频域相关运算,来估计大范围的频率偏移,它与改进的细同步算法合,能够纠正达到半个系统带宽的频偏。仿真表明这是一种准确而可靠的频率同步方案。 相似文献
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一种优化的OFDM系统同步方案 总被引:1,自引:0,他引:1
提出了一种在OFDM系统中低复杂度的符号和载波频率同步方案。该方案利用接收序列(解调以前)和本地已知序列的相关性,获得符号同步;利用OFDM信号中的保护间隔,也即一帧中的循环前缀(CP)与末尾部分的相关性,获得频率粗同步;分析了该算法的性能,给出其在噪声信道、频率选择性衰落信道中的仿真结果。结果表明,所提出的算法不仅具有低复杂度的可实现性而且有较高的精度。 相似文献
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OFDM技术在对流层散射系统中的应用 总被引:1,自引:0,他引:1
散射系统中大容量、远距离信息传输的瓶颈可以利用OFDM这一新技术来解决。利用了OFDM这一新技术可以更好地利用了有限频带资源的特点,提出了一个可以明显增加散射通信容量方法。从保护时隙、帧格式、载波数量和定时等方面进行了分析,并且针对散射系统的特点提出了一个可行性方案,并讨论了在散射信道内OFDM的校频问题。经分析,该系统完全能够实现散射的大容量、远距离通信。 相似文献
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文中在分析OFDM无线信道模型的基础上,介绍了OFDM的同步技术,主要包括符号同步、载波同步和采样率同步.同时对这些同步技术的算法进行了分析比较,指出各自的优缺点,这对今后OFDM技术的应用和研究,具有一定的借鉴意义. 相似文献
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研究了移动信道中的最大多普勒频移估计技术。分析了一种基于循环前缀的多普勒频移估计算法,该算法通过计算正交频分复用(OFDM)符号已有的循环前缀的相关函数来获得最大多普勒频移。采用广义平稳非相关散射下的多径时变瑞利信道模型,对各个算法进行了仿真试验,比较了各个算法的性能。仿真结果表明,利用多普勒分集技术,可以显著降低误码率,提高系统在移动环境下的性能。 相似文献
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This paper proposes a TSK fuzzy approach to channel estimation for Orthogonal Frequency Division Multiplexing (OFDM) systems. The information of dispersive fading channel is described by using TSK fuzzy model, which is updated by the pilot symbols. The proposed approach can trace the variation of channel and it is computationally simple. Its performance is tested via simulations. Results show that it is comparable to that of ideal Minimum Mean-Square-Error (MMSE) method, especially at the low Signal to Noise Ratio (SNR). 相似文献