16单元蜂窝移动通信双频基站天线设计

设计了一种工作在900MHz和1800MHz的16单元的蜂窝移动通信双频基站天线。针对我国移动通信频率,以基站天线的双频工作以及阵列波束赋形为目标,设计了一种满足基站天线双频辐射要求的最佳反射板形状,并通过PSO全局优化算法优化各单元馈电相位并调整其间距以实现垂直面方向图双频波束赋形的目的(即垂直面方向图在所覆盖的服务区域内具有余割波束)。该天线的水平面3dB波瓣宽度达到120,°各单元间耦合较小,并具有在驻波小于2时覆盖我国现行使用的GSM和CDMA系统,2.4GHzWLAN系统以及第三代移动通信系统的工作频段。     

基于GA 与PIM 混合方法的基站天线波束赋形设计

基站天线的波束赋形设计是提高移动通信系统信道性能的关键技术之一。将投影迭代法和遗传算法应用到板状振子型基站天线的计算中,实现基站天线的快速优化设计。首先把振子形式假设为条带形状,对振子和底板均采用RWG基函数展开,得到传统矩量法的矩阵方程,然后通过投影迭代逐步修正未知电流,进而求得天线的远场方向图与天线尺寸的关系,最后与遗传算法相结合,优化设计了斜极化基站天线的波束赋形。实验结果与设计结果相吻合,证明了该方法的实用性。     

CDMA系统下行波束赋形算法

未来的移动通信业务需求将导致下行容量远大于上行容量。在基站端采用智能天线下行波束赋形技术可以解决这一问题。本文系统分析了CDMA系统下行波束赋形的两个主要技术难点,即下行信道协方差矩阵的估计和下行波束赋形算法．并简要介绍了几种下行波束赋形算法。     

全息通感一体化：高能效的波束赋形设计

通信感知一体化是解决频谱拥塞问题的重要手段。现有的通感一体化系统依赖高功耗的相控阵，限制了其在功率受限场景中的应用。作为一种低功耗天线，可重构全息超表面可以用于替代相控阵，从而形成全息通感一体化这一新范式。在该范式中，利用可重构全息超表面作为发射天线，可以同时实现高空间自由度与低功耗，进而提升通感一体化系统的整体性能。研究了全息通感一体化系统的能效，通过联合设计基站和全息超表面的波束赋形提升系统能效。然而，由于基站的数字波束赋形和可重构全息超表面的模拟波束赋形相互耦合，使得波束赋形的联合设计具有挑战性。为了应对这一挑战，首先构建了最大化能量效率的优化问题，并提出了全息波束赋形优化算法来解决这一问题。仿真结果显示，与传统基于相控阵的通感一体化系统相比，全息通感一体化系统可以在相同发射功率和天线尺寸的条件下实现更高的能效。     

一种均匀圆阵DOA估计算法及衰落信道中的性能仿真

智能天线在第三代移动通信系统中具有广阔的应用前景，它通过空域滤波能够有效的提高移动通信系统的容量，克服共信道干扰等问题。由于第三代移动通信的基站系统普遍采用的是圆形阵列的接收天线，所以本文从实际需要出发，给出了基于ESPRIT的DOA估计和波束赋形算法并根据该算法在衰落信道模型中的性能仿真结果对其进行了详细的分析。     

智能天线非理想波束赋形对TD-SCDMA系统性能的影响

在实际的无线网络中,由于无线信道的复杂性以及DOA估计的误差,会导致智能天线系统的波束赋形出现一定程度的偏差。该文通过分析智能天线系统的原理,提出了非理想波束赋形智能天线对系统性能影响的研究方法,研究了智能天线系统的鲁棒性以及不理想波束赋形的智能天线对TD-SCDMA系统性能的影响。理论和仿真结果表明,波束赋形的准确度直接影响移动通信系统的性能,系统所能容忍的波束赋形偏差有一个固定的门限值,该门限值随着系统负载的增加而减小。     

智能天线的原理和实现

近年来,智能天线技术已经成为移动通信中最具有吸引力的技术之一。在无线基站使用一个天线阵和基于基带数字信号处理技术,对基站的接受和发射波束进行自适应的赋形,可以大大降低系统内的干扰。提高系统容量,降低发射功率并提高接收灵敏度。在大大提高系统的同时,还可以降低设备的成本。此智能天线首先使用在TD－SCDMA系统中,也能使用在CDMA FDD系统中。本文对移动通信中的智能天线技术的原理和在TD－SCDMA系统中的实现作了简要介绍。     

基于3D空间信道模型的3D波束赋形技术研究

移动数据流量爆炸式增长对小区吞吐量提出了更高的要求,同时智能终端的急剧增多,使终端之间的信号干扰越来越严重。传统基站天线阵列下倾角是固定的,波束之间干扰较大。随着有源天线技术的逐渐成熟,通过垂直维度的波束赋形动态改变天线的下倾角已经成为可能。本文通过分析已有的空间信道模型,研究了基于球形坐标系统的空间信道模型的建模方法,为3D动态波束赋形技术评估提供了信道基础;并且在提出的3D信道模型基础上评估了动态调整波束的下倾角可以减少用户之间的干扰,提高小区的吞吐量。     

遗传算法在阵列天线赋形波束综合中的应用

基于遗传算法，提出了一种新的阵列天线赋形波束综合方法，在阵列天线单元数，单元间距一定的情况下，对阵列天线单元馈电幅度，相位进行优化选择，使赋形波束达到设计要求，解决了遗传算法在阵列天线赋形波束应用时的关键技术和实现方法，进行了实验例证，获得了优良的赋形波束形状，显示了遗传算法在天线设计中的广泛应用前景。     

智能天线教学实验系统的实现

智能天线是移动通信系统中广泛采用的一种新技术.本文主要介绍在移动通信实验箱中增加智能天线实验功能时对智能天线阵列类型、下行波束赋形、上行波束成形和天线校准等关键算法的选择以及智能天线教学实验系统的整体实现方案.由于实验系统可对信道环境等实验条件做适当简化,因而可以通过合理设计,在不影响实验效果的前提下,降低实验系统的复杂度和成本.     

一种计算赋形天线增益下降的简单方法

基站天线常采用赋形技术,以提高通信质量和减小对邻区的干扰,但采用赋形技术会导致天线的增益下降,通过方向图积分方法来计算和评估赋形天线的增益下降,计算过程复杂。介绍了一种通过分析基站天线接收信号过程中馈电网络功率合成的方法,只需几步简单的运算即可得出赋形基站天线的增益下降情况。     

移动通信基站双极化智能天线扇区功率比*

根据移动通信基站天线广播波束要求,构建了基站双极化智能天线阵的空间三维方向图函数.由此,计算了工作频段内基站天线不同水平面半功率波瓣宽度、不同前后比、不同垂直面电下倾和机械下倾角时,基站天线的扇区功率比和增益.结果表明,基站天线水平面半功率波瓣宽度和前后比是影响扇区功率比的决定因素;基站天线垂直面机械下倾的扇区功率比优于电下倾的扇区功率比.     

On the optimum number of beams for fixed beam smart antennas in UMTS FDD

Fixed-beam smart antennas are a simple but effective method to boost the downlink capacity of UMTS FDD. In this paper we compare the two possible strategies. Using a four element uniform linear antenna array, we find the optimum number of fixed beams per 120/spl deg/ sector dependent on the direction of departure (DoD) spread at the base station. For the first method we find the optimum number of beams to be four for low DoD spreads and two or three for large DoD spreads. For the second method the optimum number of beams per sector is seven for small DoD spreads and goes down to four or five beams per sector for large DoD spreads depending on base station spacing. By extensive system level simulations, we show, for 1 km inter base station distance, a capacity gain of more than 160% over a conventional 3-sectored reference system by both fixed beam methods.     

A metropolitan area radio system using scanning pencil beams

A metropolitan-area radio system that, from a centrally located base station, provides continuously 360° coverage over a large service region is proposed. The base station blankets the service region with a raster of very narrow pencil beams that can be rapidly scanned to any position in synchronism with the switching sequences of a time-division-multiple-access (TDMA) assignment. By deploying multiple scanning spot beams, the allocated spectrum can be reused many times. A centralized network controller, executing an efficient TDMA assignment algorithm, dynamically allocates the resources of a small transceiver pool among the far larger number of beam positions in response to real-time requests for service. By varying the dwell time at each beam position in response to the traffic intensity of the position, highly efficient resource utilization is provided. The high antenna gain of the base station antenna provides adequate arain fade margin to permit operation in the uncongested portion of the ratio spectrum above 20 GHz. The system is particularly well suited to emerging, direct-to-end-user wideband digital service offerings     

On the design of switched-beam wideband base stations

A switch beam base-station antenna is presented. The antenna is an improvement on the Butler matrix. The input ports of the antenna are excited with equal or unequal amplitudes. The feed network is analyzed and presented in a simple manner. The antenna comprises the main part of a base station, and is useful for broadband communications. The architecture of the base station is described, and the services that can be provided are given. Finally, comments are made about the tradeoffs and benefits of the antenna in comparison to the classical Butler-matrix switched-beam and adaptive arrays.     

Multifed Printed Reflectarray With Three Simultaneous Shaped Beams for LMDS Central Station Antenna

A two-layer reflectarray is proposed as a central station antenna for a local multipoint distribution system (LMDS) in the 24.5-26.5 GHz band. The antenna produces three independent beams in an alternate linear polarization that are shaped both in azimuth (sectored) and in elevation (squared cosecant). The design process is divided into several stages. First, the positions of the three feeds are established as well as the antenna geometry to produce the three beams in the required directions. Second, the phase distribution on the reflectarray surface, which produces the required beam shaping, is synthesized. Third, the sizes of the printed stacked patches are adjusted so that the phase-shift introduced by them matches the synthesized phase distribution. Finally, the radiation patterns are computed for the central and lateral beams, showing a shaping close to the requirements. A breadboard has been manufactured and measured in an anechoic chamber, showing a good behavior, which validates the designing methodology.     

Derivation of antenna pattern shaping criteria for urban base stations using ray tracing

A novel method for the derivation of the optimum base station (BS) antenna radiation pattern in urban microcellular systems or wireless systems in general is presented. The multipath radio channel is sounded with a ray-tracing (RT) tool; then the BS antenna pattern is optimized in order to minimize channel dispersion and maximize field strength in the selected service area. The procedure can be performed for the different classes of microcellular BS sites, allowing the derivation of useful criteria for the shaping of the corresponding antenna patterns. The aim of the paper is to demonstrate the possibility of using the RT in combination with an optimization procedure to derive interesting antenna design indications.     

移动通信系统中的波束转换智能天线设计

提出了在现有GSM移动通信系统中蜂窝基站采用波束转换智能天线的设计方案,对天线系统各组成部分如天线模块、收发射频模块、射频交换矩阵模块、高速扫描接收机等功能、作用、信号关系、设计要点作了探讨。若将各相邻小区配置波束转换智能天线,可有效提高网络的载噪比。     

Performance evaluation of a cellular base station multibeam antenna

Experimental test results are used to determine the performance that can be achieved from a multibeam antenna array, with fixed-beam azimuths, relative to a traditional dual-diversity three-sector antenna configuration. The performance tradeoffs between the hysterisis level, switching time, and gain improvement for a multibeam antenna are also examined. The multibeam antenna uses selection combining to switch the signals from the two strongest directional beams to the base station's main and diversity receivers. To assess the impact of beamwidth on overall system performance, the following two multibeam antennas were tested: a 12-beam 30° beamwidth array and a 24-beam 15° beamwidth array. Both multibeam antennas were field-tested in typical cellular base station sites located in heavy urban and light urban environments. Altogether, the system performance is evaluated by investigating three fundamental aspects of multibeam antenna behavior. First, the relative powers of the signals measured in each directional beam of the multibeam antenna are characterized. Then, beam separation statistics for the strongest two signals are examined. Gain improvements achievable with a multibeam antenna compared to the traditional sector configuration are determined in the second phase of the analysis. Results indicate that in excess of 5 dB of gain enhancement can be achieved with a 24-beam base station antenna in a cellular mobile radio environment. Finally, the effects of hysterisis level and switching time are characterized based on gain reductions relative to a reference case with no hysterisis and a 0.5-s switching decision time. Useful approximations are developed for the gain effects associated with varying hysterisis levels and switching times. The resulting design curves and empirical rules allow engineers to quantify multibeam antenna performance while making appropriate tradeoffs for parameter selection