MELISSA,a new class of ground based InSAR system. An example of application in support to the Costa Concordia emergency

Ground Based Interferometric Synthetic Aperture Radars (GB-InSAR) have proved to be fully operational tools for the monitoring of ground displacement and structural deformation. The main limiting factor of the existing systems is the time to acquire a single image, typically ranging from few seconds to few minutes. This paper presents the validation and the operational use of a new system – Mimo Enhanced LInear Short SAr (MELISSA), belonging to a new class of GB-InSAR devices. MELISSA is based on a Multiple Input Multiple Output Synthetic Aperture Radar (MIMO SAR) and is capable of acquiring and processing image data at an unprecedented high speed. A configuration of the system acquiring a 0.96 m synthetic aperture and 260 m swath image in 2.6 ms was tested in a controlled environment. The results prove its ability to reach an image refreshing time smaller than 4 ms and Line-Of-Sight (LOS) displacement accuracies better than 10 μm. Thus, MELISSA was able to help with the monitoring of the Costa Concordia ship movements in the immediate aftermath of grounding during both the rescue operations and subsequent wreckage removal. The accurate displacement measurements of specific points of the structure are presented in a global interferogram sequence (2-D displacement maps of the whole structure). The collected data contributed to a precise wreck deformation reconstruction. MELISSA’s ability to update the information almost every second has proven to be extremely reassuring as early warning on potentially catastrophic movements.     

一种小型化双低频4T4R基站天线阵列设计方法

能够支持双低频4T4R的MIMO基站阵列天线已成为目前运营商布网主流,当采用常规设计时,往往造成天线尺寸过大、风载荷过高等问题.在MIMO阵列天线小型化设计时,由于各阵列间距离缩小,电磁耦合急剧上升,导致各天线水平面波束宽度恶化,性能下降严重.针对此问题,提出了一种小型化阵列天线设计方法.采用波束合成技术,利用一种功率比随频率变化的新型不等功分电桥复用一组辐射单元,这样每列天线均可复用一个窄波束宽度单元,再通过该窄波束单元与其他宽波束单元合成理想的水平面波束宽度,提升天线覆盖性能.实测结果表明：采用本文阵列天线设计方法能够得到收敛的水平面波束宽度,范围在56°~68°,同时具有较好的增益和系统隔离度,大幅改善了天线性能.     

WCDMA增强型无线技术--HSDPA

介绍了WCDMA（宽带码分多址）增强型无线技术——HSDPA（高速下行分组接入）技术,详细讨论了其关键技术：AMC（自适应调制和编码）技术、HARQ（混合自动重传请求）技术以及快速调度和MIMO（多天线发射多天线接受）.并在此基础上,就HSDPA在WCDMA系统中的实现进行了较为深入的研究.     

MIMO下视阵列SAR线阵天线构型设计

针对收发分置的MIMO模式阵列天线物理设计时,一个等效阵列可由多种物理收发阵列实现的病态问题,从测绘角度切入,依据等效相位中心原理,分析了ARTINO系统不同收发组合的优缺点。引入测绘应用关心的波段、分辨率、高程精度及工作高度等要求,优化设计了真实测绘航空平台的MIMO下视阵列SAR线阵阵元的数目和位置矢量。根据该配置进行了仿真实验,通过三维成像结果和原始仿真场景的差分对比,高程重建误差均值和标准差,以及整个场景和单独建筑物区域误差在半分辨率之内的概率值,证明了优化阵列配置的合理性和有效性。     

长期演进项目中基于移动白组织网络的虚拟多输入多输出用户配对算法研究

在长期演进项目的虚拟多输入多输出系统中,为了保证用户公平性的同时得到更大系统容量,在分析移动自组织网络和虚拟多输入多输出系统模型的基础上,提出了一种长期演进项目中基于移动自组织网络的虚拟多输入多输出配对算法。仿真结果表明,该算法得到的系统吞吐量是单输入多输出系统的3倍多,是随机配对策略的2．5倍,相比正交配对策略也平均提高了20％。同时在用户的公平性方面,还保证了低吞吐量用户的公平性。