共查询到20条相似文献,搜索用时 15 毫秒
1.
In this paper, investigated a 3-D pie-cellular-cut (PCC) scattering channel model for microcell environments, that idealizes the mobile station (MS) located inside of a 3-D scattering semispheroid and base station (BS) employing a directional antenna at the center of the semispheroid. The joint probability density functions (PDFs) and marginal PDFs of Angle of arrival (AOA) and Time of Arrival (TOA) seen at the BS and the MS in correspondence with azimuth and elevation angles are derived. The results show that the proposed 3D scattering channel model performs better compared with previously proposed 2D models for outdoor and indoor environments, which promotes the research of the statistical channel models. 相似文献
2.
High-altitude platforms (HAPs) are considered as an alternative technology to provide future generation broadband wireless communications services. This paper proposes a three-dimensional (3-D) geometry-based reference model for wideband HAP multiple-input–multiple-output (MIMO) channels. The statistical properties of the channel are analytically studied in terms of the elevation angle of the platform, the antenna arrays configuration, and the angular, the Doppler and the delay spread. Specifically, the space-time-frequency correlation function (STFCF), the space-Doppler power spectrum, and the power space-delay spectrum are derived for a 3-D non-isotropic scattering environment. Finally, a sum-of-sinusoids statistical simulation model for wideband HAP-MIMO channels is proposed. The results show that the simulation model accurately and efficiently reproduces the STFCF of the reference model. The proposed models provide a convenient framework for the characterization, analysis, test, and design of wideband HAP-MIMO communications systems with line-of-sight and non-line-of-sight links. 相似文献
3.
Antenna Array Structures Effect on Water-Filling Capacity of Indoor NLOS MIMO Channel 总被引:1,自引:0,他引:1
L Jian-gang~ L Ying-hua~ DU Juan~ LI Yun-zhuang~ WANG Xu-ying~.Continuing Education School Beijing University of Posts Telecommunications Beijing P.R. China .STMicroelectronics Beijing P.R. China .China Telecommunication Corporation Beijing P.R. China 《中国邮电高校学报(英文版)》2005,12(3)
1 Introduction Digital communication using MI MO has recently e-merged as one of the most significant technical break-throughs in modern wireless communications .Foschini ,Telatar and others saythat the capacity can beincreasedlinearly with the mini mum antenna numbers of thetransmitter and receiver if the scattering environment isrich and there is no correlation between the antennapairs at the transmitter and the receiver[1 ~2]. Toachieve these capacities coding techniques such asBLAST an… 相似文献
4.
Shouxing Qu Tet Yeap 《Vehicular Technology, IEEE Transactions on》1999,48(3):765-781
Clarke's (1968) scattering model, one of the most widely accepted channel models for the land mobile environment, is a two-dimensional (2-D) model because of the assumption of horizontal traveling plane waves. By introducing a nonzero elevation angle of the arriving wave, a three-dimensional (3-D) model is more general and accurate, especially for the urban environment. Though the concept of the 3-D model has been proposed already, there is still a lack of satisfying results regarding the distribution of the elevation angle, from both theoretical analysis and field measurement, and the power spectral density (PSD) of the received signal. In this paper, a family of functions with two parameters, {m,n}, where m and n are positive integers, for both the symmetrical and asymmetrical probability density function (PDF) of the elevation angle (EA), is proposed. Among these functions, those with odd m and n lead to analytical solutions of the PSD of the received signal in addition to satisfying other requirements for a PDF of the EA previously proposed in literature. The PSDs in closed form associated with m and n equal to one and three are derived in particular, and the autocorrelation functions are obtained numerically. Since a family of functions rather than a single function is proposed for the PDF of the EA, it provides certain flexibility in application and covers a wide range of environments. Another contribution of this paper is a new expression which directly relates the PDF of the EA in the 3-D model to the PSD of the received signal 相似文献
5.
Angular power distribution and mean effective gain of mobile antenna in different propagation environments 总被引:4,自引:0,他引:4
Kalliola K. Sulonen K. Laitinen H. Kivekas O. Krogerus J. Vainikainen P. 《Vehicular Technology, IEEE Transactions on》2002,51(5):823-838
We measured the elevation angle distribution and cross-polarization power ratio of the incident power at a mobile station in different radio propagation environments at 2.15 GHz frequency. A novel measurement technique was utilized, based on a wideband channel sounder and a spherical dual-polarized antenna array at the receiver. Data were collected over 9 km of continuous measurement routes, both indoor and outdoor. Our results show that in non-line-of-sight situations, the power distribution in elevation has a shape of a double-sided exponential function, with different slopes on the negative and positive sides of the peak. The slopes and the peak elevation angle depend on the environment and base-station antenna height. The cross-polarization power ratio varied within 6.6 and 11.4 dB, being lowest for indoor and highest for urban microcell environments. We applied the experimental data for analysis of the mean effective gain (MEG) of several mobile handset antenna configurations, with and without the user's head. The obtained MEG values varied from approximately -5 dBi in free space to less than -11 dBi beside the head model. These values are considerably lower than what is typically used in system specifications. The result shows that considering only the maximum gain or total efficiency of the antenna is not enough to describe its performance in practical operating conditions. For most antennas, the environment type has little effect on the MEG, but clear differences exist between antennas. The effect of the user's head on the MEG depends on the antenna type and on which side of the head the user holds the handset. 相似文献
6.
A 3-D reference model is proposed for multiple-input multiple-output (MIMO) mobile-to-mobile (M-to-M) multipath-fading channels. From this model, a closed-form joint space-time correlation function is derived for a 3-D nonisotropic scattering environment. Two sum-of-sinusoids-based 3-D simulation models for MIMO M-to-M multipath-fading channels are proposed. The statistics of the simulation models are verified by simulation. Finally, these simulation models are used to evaluate the effect of the space-time correlation on the outage capacity of uniform linear antenna arrays and to compare the capacities of linear, circular, and spherical antenna arrays. 相似文献
7.
Multiwavelength optically controlled phased-array antennas 总被引:1,自引:0,他引:1
A novel multiwavelength scheme is proposed and demonstrated for one-dimensional (1-D) and two-dimensional (2-D) optically controlled phased-array antenna (OCPAA) systems with true time delay (TTD). This hardware-compressive architecture employs a multiwavelength laser source in conjunction with a programmable dispersion matrix (PDM) and switched optical delay lines (SODLs) to generate all the required time delays for beam steering in 2-D phased-array antenna systems. Independent control of elevation and azimuthal scan is achieved by combining wavelength-dependent and wavelength-independent time delays. An experimental prototype of 4×2 array with 2-b×2-b resolution is constructed to demonstrate the feasibility of the multiwavelength OCPPA (MWOCPAA). Broadband linear RF phase shift is measured in both elevation and azimuthal planes over the entire bandwidth of the electro-optic (EO) modulator. System issues such as insertion loss, array size, and channel isolation are discussed. Extension of the multiwavelength scheme to a common transmit/receive (T/R) module with TTD is also described 相似文献
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9.
We present a geometric channel model to study the effect of antenna directivity on angular power distribution at the mobile
terminal in urban macrocells. The methodology reviewed in this paper integrates the antenna effect into the model geometry,
thereby facilitating a system-dependent channel characterization. As each device is limited in terms of measurement sensitivity, the effective scatterer distribution
is essentially dependent on the antenna beam pattern. Subsequently, two heuristic rules are proposed to establish the underlying
relationship between the model geometry and the corresponding wave-propagation processes. It is shown that the influence of
directional antenna is twofold. First, it alters the spatial distribution of scatterers by providing a different sample space
for the random field, and secondly, it distributes signal components into the angles-of-departure or collects them from the
angles-of-arrival by weighted combination. Important channel parameters measured at the mobile terminal such as the angular
power distribution, Doppler spectrum, and multipath shape factors are also investigated to further exemplify the usefulness
of the proposed model. 相似文献
10.
11.
Jin-Yuan Wang Jun-Bo Wang Ming Chen Jianxin Dai 《Wireless Personal Communications》2014,75(2):1099-1114
Recently, much attention has been drawn to distributed antenna systems (DAS), which are proposed to improve the performance of mobile communication systems. This paper focuses on the analysis of the average symbol error rate (SER) of DAS over a generic composite channel. Initially, a new composite channel model is considered for DAS, which is a mixture of path loss, lognormal shadowing and generalized-Gamma fast fading. This composite channel model is a generic model, which includes many well-known composite channel models as special cases. Based on the channel model, the cumulative distribution function of the output signal-to-noise ratio is obtained by employing selective transmission scheme. Moreover, by averaging the channel conditions and the positions of the MS in the cell, an approximate expression of the average SER is derived, which is a unified form of expression for many commonly used modulation schemes. Numerical results show that the derived expression of the average SER can provide sufficient precision for evaluating the SER performance of DAS under different modulation schemes. 相似文献
12.
三维空间MIMO信道接收天线阵列互耦效应及系统容量分析 总被引:1,自引:0,他引:1
针对非频率选择性瑞利衰落MIMO(multiple-input multiple-output)信道,建立了接收天线阵列的三维空间信道模型,将MIMO的一般信道建模推广到三维空间域。在建模过程中利用天线阵列在互耦效应下的等效网络模型,推导出三维空间域模型下的互耦相关性的通用表达式,阐明了互耦效应下相关性与无互耦相关性之间的关系。应用通用表达式分析了当接收端为不同的天线阵列结构时,入射信号的中心到达角和角度扩展分别对于在互耦效应下信道容量的影响。分析结果验证了不同的角度扩展对于互耦相关性的影响,揭示了在互耦效应下影响系统容量的主要因素为入射信号的平均中心到达角。 相似文献
13.
In two-dimensional (2-D) direction-of-arrival (DOA) estimation, paring the azimuth and elevation angles of multiple sources is an important issue. In this letter, we propose a new automatically paired 2-D DOA estimation method by designing the geometry of two antenna subarrays and using the propagator method (PM). A special geometry between two parallel uniform linear arrays (ULAs) with a position displacement on the axial direction is proposed to facilitate the elevation and azimuth pairing and estimation. The simulation results have shown that the proposed method can achieve the same 2-D DOA estimation performance as the existing methods, while the complexity is reduced considerably. 相似文献
14.
15.
《Vehicular Technology, IEEE Transactions on》2009,58(6):2618-2625
16.
To match complex wireless propagation scenarios,an improved 3D geometry-based stochastic model was proposed for vehicle to vehicle (V2V) communications channel.The exact relationship between the azimuth angle and elevation angle was taken into account and the corresponding space–time correlation function and space–Doppler power spectral density were derived,and the influence of important factors was analyzed.The observations and conclusions show that correlation characteristics is closely related to distribution of the scatterers and the angle of the antenna array under the non-isotropic scattering environment and is affected by the elevation angle of the antenna array under the isotropic scattering environment.And the space-time correlation characteristics in high vehicular traffic density is significantly lower than that in low vehicular traffic density.The corresponding simulation model is also derived by using a reasonable parameter calculation method.The simulation results validate the rationality of proposed model.It greatly improves analysis and simulation efficiency of V2V MIMO system. 相似文献
17.
《Microelectronics Journal》2007,38(10-11):1013-1020
A simple and accurate analytical model for the threshold voltage of AlGaN/GaN high electron mobility transistor (HEMT) is developed by solving three-dimensional (3-D) Poisson equation to investigate the short channel effects (SCEs) and the narrow width effects present simultaneously in a small geometry device. It has been demonstrated that the proposed model correctly predicts the potential and electric field distribution along the channel. In the proposed model, the effect of important parameters such as the thickness of the barrier layer and its doping on the threshold voltage has also been included. The model is, further, extended to find an expression for the threshold voltage in the sub-micrometer regime. The accuracy of the proposed analytical model is verified by comparing the model results with 3-D device simulations for different gate lengths and widths. 相似文献
18.
针对在均匀散射体分布以及空间对称的3-D室内移动通信环境,细化了对于基站(BS,Base Station)以及移动台(MS,Mobile Station)端空间角度的研究。对在指向性天线覆盖下的室内微小区移动通信环境下,模型能估计多径衰落信道的重要空时信道参数,如波达信号在水平面以及竖直平面上的信号到达角度(AOA,Angle of Arrival)以及到达时间(TOA,Time of Arrival)。数值仿真结果与2一D多径衰落信道对比表明本模型的信道参数估计结果符合理论和经验,扩展了3一D空间统计信道模型的研究和应用。 相似文献
19.
Ban-Leong Ooi 《Antennas and Propagation, IEEE Transactions on》2004,52(5):1286-1293
A modified contour integral method coupled with segmentation method has been used, for the first time, to analyze both the Sierpinski fractal carpet (SFC) antennas of different orders and an SFC antenna with electromagnetic band gap (EBG) ground plane. The close agreement between the calculated and measured results for resonant frequencies and input return losses indicates that this technique can be used to accurately predict the impedance characteristic. A novel stacked microstrip Sierpinski carpet fractal antenna using the EBG ground plane is also presented. Comparing to an ordinary microstrip fractal antenna, which has a maximum bandwidth of approximately 2%, the proposed antenna has a higher input impedance bandwidth of nearly 9%. The radiation patterns of the proposed antenna are improved due to the removal of unwanted radiation caused by the surface wave. The experimental measurement results of the proposed antenna are presented in this paper. 相似文献
20.
A new method is presented for increasing the separation between the radiating elements of a 1-D array antenna by incorporating it into a Fabry-Perot type resonant cavity with artificial magnetic conductor (AMC) walls. The AMC walls create a more uniform distribution of field within the cavity and, moreover, eliminate diffracted fields. The concept is demonstrated via 3-D full-wave simulations as well as experimental measurements for a prototype antenna. Comparison between an antenna with AMC walls and an identical reference antenna, without walls, shows a reduction in the sidelobe level. An array element separation of 2lambda is achieved whilst maintaining good radiation performance. The performance of the proposed structure is also compared to that of an antenna incorporating PEC walls. Finally, the effect of the sidewall and central AMC walls are considered separately in order to isolate their corresponding effect on the antenna performance. 相似文献