紧凑型TD-SCDMA智能天线系统仿真性能分析

目前中国移动TD-SCDMA应用实验网中智能天线主要采用常规8阵元和6阵元智能天线,但这两种智能天线体积较大、重量重,给工程施工带来了很多困难,因此,智能天线小型化成为目前研究的一个热点。本文通过系统仿真对一种小型化的紧凑型智能天线的性能进行了仿真分析,并与常规智能天线系统性能进行比较分析,来验证此天线可作为一种TD—SCDMA小型化智能天线的解决方案。     

智能天线小型化策略之双极化天线

首先介绍智能天线小型化的必要性,然后利用电磁仿真软件的仿真结果分析城区环境下极化信道的特性以及极化天线带来的极化分集效果,最后讨论双极化智能天线的结构和应用双极化智能天线应关注的问题.     

TD—SCDMA天线小型化研究

通过理论分析、仿真分析和实际测试,文章对TD—SCDMA天线小型化方案做了系统的研究,从智能天线小型化、多阵元智能天线、普通天线代替智能天线三方面进行了分析,提出7TD—SCDMA天线小型化实现方法。     

面阵体阵波束赋形及小型化研究

波束赋形是智能天线的重要技术之一.文章从理论上研究了面阵和体阵及小型化的波束赋形,解出了方向图函数,分析了赋形方向图的特征,并设计了一款小型化梯形体阵,以期有助于智能天线系统的管理、维护、优化和改进.     

TD智能天线的四大趋势

智能天线技术可以形成能量集中的波束,增强有用信号并降低干扰,而MIMO技术可以充分利用多径信息来提高系统容量。目前应用于现网的TD-SCDMA智能天线已有单极化智能天线、双极化智能天线、AEF超宽频双极化智能天线、AF/AE二合一智能天线等,随着TD-SCDMA系统技术及应用的不断发展和完善,未来智能天线将朝着电调化、一体化、小型化的方向发展和迈进。     

GPS中智能天线的设计与实现

目前对智能天线的研究主要侧重于智能天线的自适应波束形成算法和智能天线的应用两个方面,并已提出了不少高效的智能天线算法,智能天线的理论已经很成熟。对智能天线应用研究最多的是它在第三代移动通信中的应用。文中提出智能天线在GPS(全球定位系统)中的一种应用方案,它基于功率倒置算法,用DSP实现。     

单极化线形智能天线阵小型化技术研究

智能天线可以显著地提高移动通信系统的整体性能,然而,受施工、选址及环保等因素的限制,基站端智能天线采用小型化设计已成为一种趋势。设计了一款8单元(8通道)单极化线形智能天线阵。借助仿真软件,分析了单元间距对天线阵性能及小型化的影响。研究结果表明,在满足设计指标的前提下,单元间距为45 mm的紧凑型等间距线形智能天线阵的增益下降3 dB,半功率主瓣宽度增加了9,横向电尺寸减少31.11%。采用非等间距可以使智能天线阵的第一副瓣电平降低5～7 dB,横向电尺寸减少9.18%～20%。     

智能天线小型化的发展

本文首先简要介绍了TD-SCDMA智能天线的原理及面临的问题,然后对目前几种主要的智能天线小型化方案进行了分析,并给出了作者的建议.     

折叠短路式小型化双层微带天线

微带天线在各种内置天线通讯系统中有非常重要的应用.为满足便携式设备小型化的需要,该文介绍一种折叠式双层正方形微带贴片天线.此天线根据曲流原理,把常规的微带天线进行折叠.与常规微带天线相比,折叠式微带天线的尺寸减小了60%以上.折叠天线结构紧凑,便于加工制作.文中给出了天线的详细设计方案以及仿真结果.仿真结果证明该设计完全可以满足工程要求.     

浅谈分形技术在小型化微带天线中的应用

微带天线因其自身具有的体积小、重量轻、易集成等优点,自被成功研制以来便得到国内外专家学者的青睐.同时,随着信息社会的高度发展,移动终端的小型化已成为必然趋势,对终端天线的小型化需求也就更为迫切,微带天线的小型化研究对减小无线通信设备的体积非常有意义.本文在对近年来小型化微带天线的主要研究成果进行总结的基础上,重点分析了分形结构在微带天线小型化中的应用现状.     

Software radio architecture with smart antennas: a tutorial onalgorithms and complexity

There has been considerable interest in using antenna arrays in wireless communication networks to increase the capacity and decrease the cochannel interference. Adaptive beamforming with smart antennas at the receiver increases the carrier-to-interference ratio (CIR) in a wireless link. This paper considers a wireless network with beamforming capabilities at the receiver which allows two or more transmitters to share the same channel to communicate with the base station. The concrete computational complexity and algorithm structure of a base station are considered in terms of a software radio system model, initially with an omnidirectional antenna. The software radio computational model is then expanded to characterize a network with smart antennas. The application of the software radio smart antenna is demonstrated through two examples. First, traffic improvement in a network with a smart antenna is considered, and the implementation of a hand-off algorithm in the software radio is presented. The blocking probabilities of the calls and total carried traffic in the system under different traffic policies are derived. The analytical and numerical results show that adaptive beamforming at the receiver reduces the probability of blocking and forced termination of the calls and increases the total carried traffic in the system. Then, a joint beamforming and power control algorithm is implemented in a software radio smart antenna in a CDMA network. This shows that, by using smart antennas, each user can transmit with much lower power, and therefore the system capacity increases significantly     

A New Class of Miniature Embedded Inverted-F Antennas (IFAs) for 2.4 GHz WLAN Application

A new class of miniature printed embedded inverted-F antennas are proposed for operation in the 2.4–2.485 GHz wireless local-area network band. One of the proposed antennas on FR4 substrate (dielectric constant = 4.4) measures 9.2 mm by 4.1 mm and has a bandwidth of 3.5%. The peak gain of this antenna is 1.4 dBi. An overall size reduction of 70% is achieved compared to a conventional inverted-F antenna. Effects of dielectric loss tangent and material conductivity on the bandwidth and efficiency of these antennas are also investigated. Finally, two embedded antenna elements are analyzed to demonstrate the feasibility for a decoupled antenna pair consisting of switched and combining diversity schemes.     

Smart antenna based broadcasting in wireless ad hoc networks

Smart antennas have the advantage over traditional omnidirectional antennas of being able to orientate radio signals into the concerned directions in either transmission mode or in reception mode. Since the omnidirectional antenna use in broadcasting over the whole network is the source of an excessive redundancy of broadcast packet receptions within each node, we suggest using smart antennas to improve the medium usage in the case of broadcasting. We propose to adapt a current broadcast protocol to smart antenna applications and present two smart antenna broadcast approaches. We also present a comparative performance study between omnidirectional and smart antennas when broadcasting. We show that we can improve battery power utilisation and bandwidth usage with smart antennas.     

Why have smart antennas not yet gained traction with wireless network operators?

Many research and development activities have been poured into developing smart antennas for wireless communications systems. Yet despite the promise of increased network capacity and enhanced spectrum utilization, smart antenna systems have largely failed to break into the mainstream cellular networks, as operators have balked at adopting these technologies. This article examines some of the reasons why smart antennas have historically been met with resistance, and suggests that provided some identified obstacles are overcome, the proliferation of certain types of smart antennas is imminent.     

世博特殊场景下小型化智能天线的应用

智能天线是TD-SCDMA系统中使用的一项关键技术,但是由于体积大,线缆多,使用中具有很大的局限性。本文结合世博实际应用,提出了一种小型化智能天线解决方案,并通过实际测试结果证明其实用性。     

Smart antennas using electro-active polymers for deformable parasitic elements

A novel concept for implementation of smart antennas is introduced. Deformable smart materials, as parasitic elements to alter the antenna pattern, are demonstrated. Such a reconfiguration can be used for improved spectral efficiency through diversity-type techniques. The approach effectively allows replacement of much RF circuitry and the signal processing modules present in a conventional array, by simple, low-cost, low power, smart materials. A basic, proof-ofconcept prototype comprising a radiating monopole and a deformable conductive strip made of ionic polymeric-metal composite is presented. The deformable conductive strip has a voltage-controlled slant angle and its close proximity to the monopole reconfigures the pattern. Physical measurements verify the operation of the antenna. The impedance matching is also discussed.     

Miniature reconfigurable three-dimensional fractal tree antennas

This paper introduces a design methodology for miniature multiband as well as reconfigurable (i.e., tunable) antennas that exploits the self-similar branching structure of three-dimensional (3-D) fractal trees. Several fundamental relationships, useful for design purposes, are established between the geometrical structure of the fractal tree antenna and its corresponding radiation characteristics. In particular, it will be shown that the density and elevation angle of the branches play a key role in the effective design of miniature 3-D fractal tree antennas. Several design examples are considered where fractal trees are used as end-loads in order to miniaturize conventional dipole or monopole antennas. Multiband and reconfigurable versions of these miniature antennas are also proposed, where either reactive LC traps or RF switches are strategically placed throughout the branches and/or along the trunk of the trees. Included among these designs is a miniature reconfigurable dipole antenna that achieves a 57% size reduction for the center frequency of the lowest intended band of operation and has a tunable bandwidth of nearly 70%.     

A Unified MAC Layer Framework for Ad-Hoc Networks With Smart Antennas

Smart antennas represent a broad variety of antennas that differ in their performance and transceiver complexity. The superior capabilities of smart antennas, however, can be leveraged only through appropriately designed higher layer network protocols, including at the medium access control (MAC) layer. Although several related works have considered such tailored protocols, they do so in the context of specific antenna technologies. In this paper, we explore the possibility for a unified approach to medium access control in ad hoc networks with smart antennas. We first present a unified representation of the PHY layer capabilities of the different types of smart antennas, and their relevance to MAC layer design. We then define a unified MAC problem formulation, and derive unified MAC algorithms (both centralized and distributed) from the formulation. Finally, using the algorithms developed, we investigate the relative performance trade-offs of the different technologies under varying network conditions. We also analyze theoretically the performance bounds of the different smart antenna technologies when the available gains are exploited for rate increase and communication range increase.     

智能天线技术

在分析了智能天线的特点的基础上,对智能天线中所涉及的理论方法进行了深入探讨。根据天线波束处理和形成方式的不同,详细介绍了智能天线的体系结构和分类;具体阐述了实现智能天线技术中所采用的算法,并根据算法的运算性能、测量要求等不同点,给出了相应的优选策略,最后对智能天线的应用现状和发展前景进行了总结和展望。