高Q Ba(Zn_(1/3)Ta_(2/3))O_3介质谐振器材料及其在毫米波系统中的应用

叙述了Ｂａ（Ｚｎ１／３Ｔａ２／３）Ｏ３介质谐振器材料的制备、结构、微波性能及典型应用。Ｂａ（Ｚｎ１／３Ｔａ２／３）Ｏ３介质材料介电常数εｒ为２９．５，频率温度系数τ≈０（－５５～＋８５℃），１０ＧＨｚ下最大无载Ｑ值１４７００，在２８ＧＨｚ测得Ｑ值约为４８００。这种材料具有高Ｑ值，特别适用于Ｘ以上波段作为振荡器电路中频率稳定元件。用这种介质谐振器已研制出８ｍｍ介质稳频微带耿氏振荡器，频率稳定度小于１０×１０－６／℃，最大输出功率达１８０ｍＷ。     

Survivable millimeter-wave mesh networks

Millimeter-wave mesh networks have the potential to provide cost-effective high-bandwidth solutions to many current bandwidth-constrained networks including cellular backhaul. However, the availability of such networks is severely limited due to their susceptibility to weather, such as precipitation and humidity. In this paper, we present a rigorous approach to survivable millimeter-wave mesh networks based on experimentation, modeling, and simulation. Individual link performance is characterised using frame error-rate measurements from millimeter-wave transmissions on test links over a period of one year. A geometric model based on radar-reflectivity data is used to characterise rain storms and determine their impact on spatially correlated links of a mesh network. To mitigate the impact of link impairments on network services, we present two cross-layered routing protocols to route around the failures: P-WARP (predictive weather-assisted routing protocol) and XL-OSPF (cross-layered open shortest-path first). We conduct a performance analysis of the proposed mesh network under the presence of actual weather events as recorded by the US National Weather Service. Results show that the proposed approach yields the highest dependability when compared against existing routing methods.     

Dielectric properties of porous silicon for use as a substrate for the on-chip integration of millimeter-wave devices in the frequency range 140 to 210?GHz

In this work, the dielectric properties of porous Si for its use as a local substrate material for the integration on the Si wafer of millimeter-wave devices were investigated in the frequency range 140 to 210 GHz. Broadband electrical characterization of coplanar waveguide transmission lines (CPW TLines), formed on the porous Si layer, was used in this respect. It was shown that the dielectric parameters of porous Si (dielectric permittivity and loss tangent) in the above frequency range have values similar to those obtained at lower frequencies (1 to 40 GHz). More specifically, for the samples used, the obtained values were approximately 3.12 ± 0.05 and 0.023 ± 0.005, respectively. Finally, a comparison was made between the performance of the CPW TLines on a 150-μm-thick porous Si layer and on three other radiofrequency (RF) substrates, namely, on trap-rich high-resistivity Si (trap-rich HR Si), on a standard complementary metal-oxide-semiconductor (CMOS) Si wafer (p-type, resistivity 1 to 10 Ω.cm) and on quartz.

PACS

84.40.-x; 77.22.Ch; 81.05.Rm     

Towards the global modeling of InGaAs-based pseudomorphic HEMTs

We utilize a 3D full-band Cellular Monte Car- lo (CMC) device simulator to model ultrashort gate length pseudomorphic high-electron-mobility transistors (p-HEMTs). We present the static dc device characteristics and rf response for gate lengths ranging from 10 nm to 50 nm. Preliminary passive results using 3D full-wave Maxwell solver are also presented to illustrate the usefulness of and insight that a future coupled full-band/full-wave simulator will provide in more accurately, modeling the high frequency performance of p-HEMTs.     

基于贝叶斯压缩感知的毫米波MIMO信道估计

针对毫米波大规模多输入多输出(MIMO)通信系统中存在的硬件成本高、能耗大等问题,混合模拟-数字的收发机架构是一个很有前景的解决方案,然而系统的信道估计问题却成为一个挑战。在考虑正交频分复用和频率选择性衰落信道模型的前提下,提出了一种使用贝叶斯压缩感知理论来估计信道的方法。贝叶斯压缩感知算法可以在稀疏信道先验知识不完备的情况下,实现更高精度的信道估计。仿真结果验证了所提方法的有效性,与正交匹配追踪算法相比,在信噪比为30dB时,归一化均方误差降低了约25dB。     

ROD-based hybrid TH precoding and combining for mmWave large-scale MIMO systems

Hybrid precoding is one of key techniques for millimeter wave (mmWave) large-scale multiple-input multiple-output (MIMO) systems. This paper considers a nonlinear hybrid precoding architecture which consists of a nonlinear unit, a reductive digital precoder and a constant modulus radio frequency (RF) precoder, and presents a novel hybrid Tomlinson-Harashima (TH) precoding and combining algorithm. Firstly, due to the intractability of the sum rates maximization problem for such a nonlinear hybrid precoding architecture, a tractable three-stage optimization problem is constructed through the lower bound of the sum rates, which allows the digital precoding matrix, the RF precoding matrix and the RF combining matrix to be optimized sequentially and independently. Then, in order to solve the three-stage optimization problem effectively, a novel row orthogonal decomposition (ROD) is defined. Based on the ROD, it is interesting that the necessary and sufficient condition of the optimal digital precoding matrix can be obtained, and a near-optimal RF precoding matrix can be derived. Finally, the optimization of the RF combining matrix is reformulated as a unimodular quadratic programming and solved by a generalized power method. Theoretical analyses and simulations indicate that the proposed ROD-based hybrid TH precoding and combining algorithm can offer a higher sum rates and a lower bit error rate with a comparable complexity in comparison to the previous works.     

Power consumption analysis of access network in 5G mobile communication infrastructures — An analytical quantification model

Energy consumption growth of the fifth-generation (5G) mobile network infrastructure can be significant due to the increased traffic demand for a massive number of end-users with increasing traffic volume, user density, and data rate. The emerging technologies of radio access networks (RAN), e.g., millimeter-wave (mm-wave) communication and large-scale antennas, make a considerable contribution to such an increase in energy consumption. The multiband 2-tier heterogeneous network (HetNet), cloud radio access network (C-RAN), and heterogeneous cloud radio access network (H-CRAN) are considered the prospective RAN architectures of the 5G mobile communication. This paper explores these novel architectures from the energy consumption and network power efficiency perspective considering the varying high volume traffic load, the number of antennas, varying bandwidth, and varying density of low power nodes (LPNs), integrated with mm-wave communication and large-scale multiple antennas. The architectural differences of these networks are highlighted and power consumption analytical models that characterize the energy consumption of radio resource heads (RRHs), base band unit (BBU) pool, fronthaul, macro base station (MBS), and small cell base stations (SCBs) in HetNet, C-RAN, and H-CRAN are developed. The network power efficiency with the consideration of propagation environment and network constraints is investigated to identify the energy-efficient architecture for the 5G mobile network. The simulation results reveal that the power consumption of all these architectures increases in all considered scenarios due to an increase in power consumption of radio frequency components and computation power. Moreover, CRAN is the most energy-efficient RAN architecture due to its cooperative processing and decreased cooling and site support devices and H-CRAN consumes most of the energy compared to other 5G RAN architectures mainly due to a high level of heterogeneity.     

面向动态目标的汽车毫米波雷达防撞系统设计

汽车毫米波雷达防撞(AMRV)系统是实现汽车主动安全驾驶的关键装置,针对行驶中汽车的运动特点,研究了面向动态目标的汽车毫米波雷达测距和测速原理,设计了汽车毫米波雷达防撞系统,并运用先进设计系统软件(ADS)对该系统进行了计算机仿真实验,实验表明所设计的系统符合防撞雷达的要求.     

Ka波段小型化FMCW雷达低中频信号处理技术研究

为了显著降低FMCW雷达后端数字信号处理电路的电路面积与电路成本,提出了低中频的设计思路,利用频谱搬移技术对目标信号进行下变频处理,使目标信号频率在20KHz以下,相比直接对目标信号进行处理,A/D采样率得到减小,对3.5m处的目标进行测试,测试结果得到目标频率从160KHz有效的降低到了10KHz,验证了低中频方法的可行性,满足小型化低成本雷达应用需求。     

双谱用于毫米波雷达目标特征提取的研究

在毫米波雷达系统中,信噪比对作用距离的影响很大。本文利用双谱技术提取出目标信号双谱的局部相位信息作为特征矢量;该特征良好的抗噪性大大降低了目标识别对雷达系统信噪比的要求,从而提高了毫米波雷达的灵敏度及作用距离。