TDD(Time Division Duplex) is one of the two duplex modes.TD-SCDMA(Time division Synchronous CDMA) is the first TDD-based cellular mobile system which is commercialized in wide area and large scale and TD-SCDMA is also...TDD(Time Division Duplex) is one of the two duplex modes.TD-SCDMA(Time division Synchronous CDMA) is the first TDD-based cellular mobile system which is commercialized in wide area and large scale and TD-SCDMA is also the first cellular mobile system which adopted smart antenna technology,also called as beamforming.As the long term evolution of TD-SCDMA,TDLTE(A)(Time Division-Lone Term Evolution,and TD-LTE Advanced) introduced OFDM(Orthogonal Frequency Division Multiplexing)and enhanced smart antenna technology together with MIMO(Multiple Input Multiple Output),which are adopted by LTE FDD(Frequency Division Duplex) either.It is indicated that TD-SCDMA and TD-LTE(A)have opened a sustainable utilization era of TDD and smart antenna Technologies in the wireless mobile communication.This paper aims to present a systematic introduction to TDD-based mobile communications from TD-SCDMA to TD-LTE and beyond and its comparisons to FDD,with particular focuses on TDD key technologies,principles of TDD cellular mobile systems,TDD evolution path,and future TDD 5G directions.We hope that this paper will provide a comprehensive overview of TDD technology upgrade and its standard evolution,and serve as a valuable reference for research on 5G mobile communication systems.It is believed that TDD will play more important role in 5G.展开更多
微带天线具有轻的重量、较小的体积及散射截面等特点，可设计为无线电高度表的天线。采用组阵的方式把矩形贴片单元组成宽频带，高增益的阵列天线，增加基板厚度扩展频带，良好的多枝节阻抗匹配获得较大增益。应用此结构设计四元微带天...微带天线具有轻的重量、较小的体积及散射截面等特点，可设计为无线电高度表的天线。采用组阵的方式把矩形贴片单元组成宽频带，高增益的阵列天线，增加基板厚度扩展频带，良好的多枝节阻抗匹配获得较大增益。应用此结构设计四元微带天线阵，中心频率为4．3 GHz ，带宽BW＞200 M Hz ，采用等幅并联馈电的方式，通过 HFSS进行仿真优化，仿真结果显示驻波比小于2，最大增益为11．3 dB ，3 dB波束宽度约为46°。实测结果为：驻波比小于2频带扩展到4．08～4．52 GHz ，最大增益为10．33 dB ，达到设计要求。该天线阵简单的结构，良好的特性可运用到小型飞行器高度表系统中。展开更多
基金supported in part by the National Natural Science Foundation of China for Distinguished Young Scholar,Grant Number:61425012
文摘TDD(Time Division Duplex) is one of the two duplex modes.TD-SCDMA(Time division Synchronous CDMA) is the first TDD-based cellular mobile system which is commercialized in wide area and large scale and TD-SCDMA is also the first cellular mobile system which adopted smart antenna technology,also called as beamforming.As the long term evolution of TD-SCDMA,TDLTE(A)(Time Division-Lone Term Evolution,and TD-LTE Advanced) introduced OFDM(Orthogonal Frequency Division Multiplexing)and enhanced smart antenna technology together with MIMO(Multiple Input Multiple Output),which are adopted by LTE FDD(Frequency Division Duplex) either.It is indicated that TD-SCDMA and TD-LTE(A)have opened a sustainable utilization era of TDD and smart antenna Technologies in the wireless mobile communication.This paper aims to present a systematic introduction to TDD-based mobile communications from TD-SCDMA to TD-LTE and beyond and its comparisons to FDD,with particular focuses on TDD key technologies,principles of TDD cellular mobile systems,TDD evolution path,and future TDD 5G directions.We hope that this paper will provide a comprehensive overview of TDD technology upgrade and its standard evolution,and serve as a valuable reference for research on 5G mobile communication systems.It is believed that TDD will play more important role in 5G.
文摘微带天线具有轻的重量、较小的体积及散射截面等特点，可设计为无线电高度表的天线。采用组阵的方式把矩形贴片单元组成宽频带，高增益的阵列天线，增加基板厚度扩展频带，良好的多枝节阻抗匹配获得较大增益。应用此结构设计四元微带天线阵，中心频率为4．3 GHz ，带宽BW＞200 M Hz ，采用等幅并联馈电的方式，通过 HFSS进行仿真优化，仿真结果显示驻波比小于2，最大增益为11．3 dB ，3 dB波束宽度约为46°。实测结果为：驻波比小于2频带扩展到4．08～4．52 GHz ，最大增益为10．33 dB ，达到设计要求。该天线阵简单的结构，良好的特性可运用到小型飞行器高度表系统中。
