基于液晶聚合物的双陷波可穿戴天线的设计

基于超薄液晶聚合物柔性材料,设计了一种满足无线体域网(WBAN)需求的双陷波UWB可穿戴天线。该天线由椭圆形贴片、锥形三叉戟共面馈线和梯形地板组成。通过分别在辐射贴片上蚀刻椭圆开口谐振环和在共面馈线上蚀刻n形槽以实现双陷波特性。该天线采用共面波导的馈电方式,具有良好的共面性,易于与载体共形。经网络矢量分析仪测试结果表明,该天线在3. 1~10. 6 GHz的超宽带频段内回波损耗小于-10 d B的同时,在4. 88~6. 15 GHz和7. 55~8. 51 GHz内拥有双陷波特性,可抑制WiMAX和ITU 8 GHz频段对系统产生的干扰。与以往的可穿戴天线相比,该天线厚度仅为0. 1 mm,且柔性可弯曲。此外,对天线在弯曲情况下进行测试,天线特性基本保持不变。     

WiMax近场干扰对UWB系统特性影响的仿真研究

研究了超宽带（UWB）无线通信系统抗WiMax系统的近场电磁干扰能力,为此,首先构建了包括UWB系统和WiMax近场电磁干扰等效的分析模型;其次,基于该分析模型研究了WiMax近场干扰对IEEE 802.15a UWB系统接收灵敏度的影响,得到了在给定场景和WiMax系统参数条件下,UWB系统接收灵敏度的回退量ΔS与其传输速率的关系曲线模型。该关系曲线模型对UWB＋WiMax双模系统共存设计具有重要的理论指导意义。     

UWB的抗干扰技术研究

文中针对超宽带（UWB）信号的抗多用户干扰，提出了一种抗多用户干扰的多用户检测器。理论分析和仿真说明提出的解相关检测器是一种低复杂度的检测器，减少了计算复杂度且性能优于传统的检测器。同时对发射信号增加了一个参数，提出了一种改进的多用户检测器，而此检测器的性能又得到了进一步的改善。     

一个紧凑的梯形领结无芯RFID标签的设计

提出了一种紧凑、低成本、可完全印制的缝隙加载领结型无芯射频识别标签的设计。标签由2个梯形金属贴片组成,2组谐振频率邻近的缝隙谐振器分别加载在2个贴片上。在不增加缝隙间相互耦合的前提下,标签在超宽带频段内容纳的数据位数提高了1倍,在35mm×33mm的合理尺寸内,12个缝隙谐振器对应12位数据。仿真给出了标签的雷达散射截面积曲线,实测是在双站天线配置下进行,在频域内测出了传输系数s21。实测和仿真结果一致,验证了本设计的合理性。该标签具有高数据位数和低成本,因其只需1个导电层,所以能被直接印刷在ID卡甚至纸张上。     

宽带系统中低复杂度RAKE接收机的性能研究

基于IEEE 802.15.3a建议的超宽带密集多径信道模型,对采用最大比和等增益两种合并方式的RAKE接收机的高速超宽带通信系统的性能进行了研究.理论分析和计算机仿真结果表明,在密集多径环境下,采用复杂度相对较低的等增益合并SRAKE接收机,可以使通信系统达到良好的误码率性能,所以其更适合于超宽带通信系统.     

Application of power transformation and moments in time based UWB ranging

For ultra-wideband (UWB) ranging, TOA estimation with the energy detection (ED) receiver is to detect the energy sample that contains the first path (FP) signal in dense multipath. Threshold crossing (TC) is used frequently. However, it is difficult to determine the threshold. Some threshold setting methods are based on constant false alarm rate (CFAR) and the chi-squared distribution. However, the distribution is complicated. Moreover, it depends on the degree of freedom (DOF). If the DOF used is wrong, it will degrade the detection performance. The study bypasses the distribution. We first examine the distribution of the output of the ED receiver after power transformation. Based on the new characteristics of the transformed data and approximate distributions, we propose some practical TOA estimation methods. Similarly, the moments of the output of the ED receiver, such as the second or one-third order moments, are also analysed and used. The proposed methods are easy to implement and can achieve about the same ranging performance with methods based on the chi-squared distribution. We provide both theoretical and simulation results to prove their effectiveness.     

基于UWB系统的井下车辆高精度定位研究

随着无线通信技术的进步,超宽带(UWB)技术从缩减硬件成本及定位精度的提升都有了大幅的进步,因此其在定位系统中的使用越来越多。通过研究适用于在井下巷道环境的高精度定位方法,研制出了一套适用于井下环境的超宽带无线车辆定位系统。试验结果显示,该系统定位精度高,对进一步实现井下的车辆无人自主导航具有非常大的支撑作用。     

一种新型的陷波天线

设计了一种新型的超宽带天线,具有小型化,2.0~10.6GHz的工作带宽及全向性的特点。基于该超宽带天线提出了一种新的实现陷波特性的方法,在天线的地板上添加一个近似半圆的谐振单元,该单元与辐射部分通过一个通孔相连,并且所加的结构对原始超宽带天线的其他特性影响很小。同时给出了该方法的等效电路。仿真与实测结构均表明该超宽带天线驻波比(VSWR)小于2的阻抗带宽是2.0~10.6GHz,天线在5.0~5.9GHz处有明显的陷波特性,很好的覆盖了无线局域网(WLAN)(5.125~5.85GHz)的工作频段。可以解决超宽带通信频段与WLAN间的电磁干扰问题,实现频谱兼容。     

Performance analysis of multiple‐input multiple‐output relay networks based impulse radio ultra‐wideband

In this paper, we study the performance of time hopping pulse position modulation for impulse radio ultra‐wideband. We consider relay network applying decode‐and‐forward protocol. The channels between nodes adopt the IEEE 802.15.4a norms. The bit error rate performance is analyzed considering the effect of interference. Our results show significant improvement due to the diversity gain provided by the relay nodes. However, the performance is limited when multiple access interference (MAI) is present. To combat the MAI effect and further improve the detection reliability, we propose to use antenna selection at the relay. The relay receiver is assumed to be equipped with multiple antennas, and only the best antenna is selected. This is shown to improve the performance in the presence of MAI and improve the diversity gain.Copyright © 2013 John Wiley & Sons, Ltd.