Maximum directivity beam-former at 60 GHz with optical feeder

We present an optically controlled 60 GHz array antenna which may be used as a smart antenna in an envisaged broadband mobile communication system. The desired field patterns of the antenna were synthesized using the maximum directivity beam-forming algorithm which enables an optimum radio link to a selected mobile terminal to be created while the signals of other terminals are suppressed by the s of the antenna's field distribution. The 60 GHz signals were generated by optically heterodyning the signals of two laser diodes. The field distribution of the antenna was formed by a silica based photonic beam-forming network. The experimentally obtained data confirmed the calculated field patterns.     

智能天线系统模拟权值乘法器的设计

提出和实现了一种智能天线系统的模拟权值乘法器。这种乘法器将智能天线阵接收到的基带信号与模拟权值进行相乘,实现了智能天线的波束形成。其处理速度快,无量化误差,无需数/模和模/数转换,无需存储空间等外部设备,硬件完全由乘法器芯片和运放芯片组成,模拟电路简单,实现和调试方便。仿真和实验的对比结果表明,提出的模拟权值乘法器具有较强的可行性和可靠性。     

特殊覆盖场景下的广播波束赋形应用研究

利用广播波束赋形技术实现小区覆盖优化是近来智能天线的一个研究热点,但是目前的研究主要集中在65°、90°等常见广播波束赋形应用上。首先介绍了智能天线广播波束赋形的基本方法,在此基础上总结了有特殊广播覆盖需求的几种常见场景,将其作为目标覆盖分析了如何生成对应的广播波束权值,并通过实验验证了特殊广播覆盖场景下权值的赋形效果。     

智能天线系统模拟权值乘法器的设计

提出和实现了一种智能天线系统的模拟权值乘法器。这种乘法器将智能天线阵接收到的基带信号与模拟权值进行相乘,实现了智能天线的波束形成。其处理速度快,无量化误差,无需数模、模数转换,无需存储空间等外部设备,硬件完全由乘法器芯片和运放芯片组成,模拟电路简单,实现和调试方便。仿真和实验的结果对比表明提出的模拟权值乘法器具有较强的可行性和可靠性。     

基于子阵列的低轨星载多波束相控阵天线的设计与实现

该文针对采用CDMA通信体制的低轨通信卫星,设计了具有等通量覆盖的平面阵列多波束天线,克服了卫星波束大角度扫描带来的边缘问题和远近效应。采用遗传算法对正六边形天线阵列进行综合,结合子阵分割理论,在波束空间和阵元空间进行子阵分割,简化了波束赋形的参量数目,同时还提出了一种波束成形网络复用结构,节省了2/3的资源。最后研制了16波束相控阵发射天线,其平面近场测试结果表明天线各指标都符合设计要求,有效验证了算法的正确性。     

基于色噪声背景下的自适应波束形成研究

色噪声环境下自适应波束形成技术能有效适应阵列天线系统的实际应用场景。首先分析了色噪声环境下自适应波束形成技术性能,重点研究了有限次快拍下自适应波束畸变产生的原因,其次,在已知噪声协方差情况下,通过对噪声相关矩阵的改进设计,降低了色噪声协方差矩阵对自适应波束形成影响。计算机模拟仿真结果表明:提出的自适应波束形成算法在色噪声环境下具有较好的波束保形能力。     

无线通信中基于线性预测和参数反馈的下行波束形成方法

本文基于最大信号噪声比准则(MSNR，Maximum Signal Noise Ratio)提出一种新的下行波束形成方法，即根据天线收发的互易性原理，通过上行波束形成得到的上行天线阵列矢量，变换而得到下行天线阵列矢量，再通过移动端Rake接收机的合作，反馈回每一径的衰落系数，考虑到存在传输和处理时延并且在此时间内信道有明显变化时，反馈的衰落系数存在误差。因此，本文采用了信道预测的方法，估计即时衰落系数，这样求得期望信号的相关矩阵，计算相应的最大广义特征值所对应的特征矢量，进行下行波束形成。     

Hybrid beam-forming and beam-switching for OFDM based wireless personal area networks

In this paper, we propose a hybrid beam-forming and beam-switching technique for OFDM based wireless personal area networks (WPAN). In order to compromise between performance and computational cost and overheads for the channel side information feedback, the proposed system employs hybrid beam-forming and beam-switching, where the block beam-switching using a predefined beam codebook is used at the transmitter while the optimum per-subcarrier beam-forming is used at the receiver. To verify the performance of the proposed scheme, the effective SNR gain over the single antenna transmission system is investigated along with the spectral efficiency bound for some of the channels developed by the IEEE 802.15.3c task group. For comparison, the performance of the optimum per-subcarrier beam-forming and the block beam-switching are also examined.     

Design of a multiple-beam forming network using CORPS optimized for cellular systems

The design of beam-forming networks (BFNs) for a multibeam-steerable antenna array using Coherently Radiating Periodic Structures (CORPS) in cellular mobile communication systems is presented. In this paper, the CORPS technology is introduced and applied to the design of beam-forming networks in cellular systems for the first time. The CORPS-BFNs proposed show improved performance over the common way to feed antenna arrays used in mobile systems. In this design, the input ports of the feeding network design are optimized using the particle swarm optimization (PSO) algorithm. Two 2-beam design configurations of CORPS-BFN for a multibeam-steerable linear array on a cellular scenario are proposed and analyzed. Simulation results show the benefits of BFNs based on CORPS on a cellular mobile scenario based on the array factor response, in terms of side lobe level (SLL) and signal-to-interference (SIR) improvement capability. Furthermore, results for average SIR improvement, signal to interference plus noise power ratio (SINR) and BER are discussed.     

Adaptive power control and beam-forming joint optimization in cognitive radio networks

A novel adaptive power control and beam-forming joint optimization algorithm is proposed in cognitive radio(CR) underlay networks,where cognitive network share spectrum with primary network which spectrum is licensed.In this paper,both primary base station(PBS) and cognitive base station(CBS) are all equipped with multi antennas,while each primary user(PU) and cognitive user(CU) has only one antenna.Different from traditional algorithms,an adaptive weight factor generating solution is supplied to different access users(both PUs and CUs) in this paper,and the different priority of users is also considered,because PUs have higher priority,the weight factor of PUs is fixed as constant and signal-to-interference and noise ratio(SINR) threshold is unchanged,while for CUs,it is set adaptively and SINR threshold is also changed accordingly.Using this algorithm,the transmit power is decreased,which relax the strict requirements for power amplifier in communication systems.And moreover,owing to PUS has fixed SINR threshold,the calculated SINR at receiver is nearly unchanged,but for CUs,the SINR is changing with the adaptive weight factor.Under the assurance of quality of service(QoS) of PUs,the solution in this paper can enable CRs access to the CR network according to adaptive SINR threshold,therefore which supplies higher spectrum utilization efficiency.     

Technology Considerations for the Use of Multiple Beam Antenna Systems in Communication Satellites

The general usage of multibeam antennas in satellite communication system is reviewed, and design constraints for a six-beam reconfigurable satellite antenna system are considered. These show that losses in the variable beam-forming network (BFN) Iimit performance achievable with a conventional common-power-amplifier/receiver system. An alternative design for an active BFN is presented, and relative performance predicted at 4/6, 11/14, and 20/30 GHz.     

Broadband circularly polarised high efficiency active antenna

A broadband circularly polarised (CP) high efficiency active antenna is presented, where the antenna is integrated directly with a high efficiency class-E power amplifier (PA). The printed antenna is employed not only as a broadband CP radiator but also as a harmonics-termination load network for the class-E PA. Measured results demonstrate broadband CP radiation and high efficiency.     

阵列天线波束成形技术在宽带CDMA下行链路中的应用

本文利用自适应天线阵列上行链路信号到达角估计信息,并结合导频辅助下行链路信道矩阵估计值,在前人提出的具有反馈特性的自适应发送阵列原理基础上,提出一种简单可行的宽带CDMA下行链路天线阵列波束成形权重计算方法,并进一步分析了到达角估计误差和信道信息反馈时延对权重计算的影响,最后给出系统误码率性能的计算机仿真结果。     

低副瓣智能天线阵型研究

由于智能天线所处电磁环境的特殊性,实现低副瓣特性及快速波束赋形尤其重要。本文从阵型角度出发,计算了圆阵中心阵元、圆阵层数及阵元密度分布对于降低副瓣的作用,并分析了球面阵列的辐射特性;所得结论可供智能天线的阵型设计参考。     

Performance analysis of smart antenna test-bed operating in awide-band CDMA channel

In this paper, we present a performance analysis of a smart antenna system operating in a wide-band CDMA wireless-local-loop channel using a beam-forming module (BFM) that has been implemented on a digital signal processor (TMS320C6701) board. We first show the results of computer simulations obtained from the modeled received (RX) signals through a test-bed system consisting solely of baseband signal processing parts, i.e., modeled RX data-generating PC, BFM for computing the optimal weight vector and interfacing module. A test-bed system of the entire base station is then implemented to evaluate the adaptive beam-forming function with the actual wireless signals. This test-bed system includes several subscribers, as well as the array antenna, RF modules, and other receiving parts required at the cell site     

A four-input beam-forming downconverter for adaptive antennas

A four-input beam-forming downconverter for adaptive antennas is described. It consists of 2-bit variable gain amplifiers (VGAs), 5-bit local oscillator (LO) signal phase shifters using double RC-bridge circuits, and mixers. The VGAs adjust gain deviation between signal paths. A differential-signal-to-eight-phase-signal converter is employed as a part of the LO phase shifter to reduce the chip size. A maximum phase error of 4.1/spl deg/, which is less than 1/2 LSB, is achieved. This error value indicates that the required phase shifter accuracy and the necessary isolation between the VGAs has been achieved. This beam-forming IC is applicable to receivers with adaptive antennas, and is expected to help to reduce the costs of adaptive antenna systems.     

TD-LMS在TD-SCDMA上行接收机中的应用

智能天线技术是TD-SCDMA系统中的一项关键技术。本文将研究TD-LMS(Transform Domain Least Mean Square)在TD-SCDMA上行自适应波束成型中的应用。首先通过误比特性能的比较发现基于小波的正交阵比常用的离散余弦变换正交阵更加适合于TD-LMS算法；其次为了检验这样一种算法的实用性，研究了定点计算的性能。蒙特卡罗仿真和复杂度分析的结果表明，基于小波变换的TD-LMS算法可以在自适应波束成型中得到应用以达到性能和复杂度的折衷。     

基于超表面的天线多波束偏转技术研究北大核心CSCD

5G移动通信对天线提出了多极化、多频段、多波束等更高的技术需求。超表面具有很强的电磁调控能力,利用这一特性可以实现天线多波束偏转。本文首先提出新型的基于行波激励网络的双波束偏转方法,利用超表面实现定向波束可控,设计了单频低副瓣高增益的双波束超表面天线。其次,提出基于多相位自由度理论的双频行波激励网络,结合双频超表面,设计了双频双波束偏转角可独立控制的超表面天线。在此基础上,提出基于正相位响应理论的稳定波束偏转角的方法,设计了具有稳定波束的±45°双极化超表面天线。与传统多波束方法相比,本方法省略了复杂的波束形成网络,设计简单、结构紧凑,而且能够实现双频、双极化等特性,可为新一代移动通信天线的研制提供技术思路。     

WCDMA系统中基于阵列天线的空时滑动相关器

文中针对使用阵列天线的宽带码分多址(WCDMA)系统，提出了一种新的用于定时搜索和波束形成权值计算的空时滑动相关器(STSC)，利用信号的时域和空域特性，融合了空域波束形成技术，提高了接收信号的信干噪比。STSC可以有效估计多径信号的传输时延，同时捕获自适应波束形成的权值。算法具有低的运算复杂度，仿真结果表明该算法具有好的时延捕获和波束形成权值捕获性能。     

A novel fully integrated transmitter front-end with high power-added efficiency

A novel fully integrated transmitter front-end with a simple structure is proposed to obtain both high power-added efficiency (PAE) and a compact RF-front structure. To have all these characteristics, a novel antenna operating as a radiator, a harmonic tuning circuit, and an output matching network of the power amplifier is proposed. Therefore, the direct integration of the output of the power amplifier and antenna can be achieved without any impedance transformers. From the measured results and fabrication, it is shown that the proposed transmitter front-end provides high PAE of 67.5% and compact and integrated RF-front structure by the size reduction of 43% compared with the conventional class-F active antenna for high PAE.