STUDY OF RADIO DEVICES ON 2.4GHZ ISM BAND IN PHYSICAL PHASE

In the unlicensed 2.4GHz ISM band,there is not only IEEE 802.11 wireless systems being used,but also some other devices,such as residential microwave oven,Bluetooth devices,and cordless phone.All these devices that are not used for the data communica- tions cause unintentional interference that will degrade the WI-FI system.In this paper,the transmission powers for common RF devices are measured and the SIR(signal-to-interference ratio)of different interferers to Wi-Fi is also studied.With this informati...     

一种5.8 GHz磁控管谐振系统的模拟分析

利用HFSS结合等效电路对一种18叶片5.8 GHz磁控管的谐振系统进行了冷态模拟与分析,利用Master/Slave边界条件对磁控管谐振腔模型进行了改进,对叶片端部尺寸对磁控管谐振系统的影响进行了分析,分析结果与实验结果相吻合。为磁控管谐振系统的设计提供了依据。     

Metal‐frame‐integrated eight‐element multiple‐input multiple‐output antenna array in the long term evolution bands 41/42/43 for fifth generation smartphones

A metal‐frame‐integrated eight‐antenna array operating in the long term evolution bands 41/42/43 (2.496 GHz‐2.69 GHz, 3.4 GHz‐3.8 GHz) for future fifth generation multiple‐input multiple‐output (MIMO) applications in smartphones is presented and discussed. The proposed eight‐antenna MIMO array is formed by integrating four identical building blocks, each of which consists two dual‐mode monopole antenna elements with a neutralization line (NL) embedded in between. Part of the metal frame is exploited to increase the effective resonant length of the monopole antenna. By using the wideband NL, two transmission dips can be generated, and thus an improved isolation (>10 dB) is achieved. The proposed antenna array was simulated and experimentally tested. Good antenna efficiency (>44%) and low envelope correlation coefficient (<0.2) were obtained in the bands of interest. In an 8 × 8 MIMO system with 20 dB signal‐to‐noise ratio, the calculated ergodic channel capacity was as high as 38 bps/Hz in the low band, and 38.3 bps/Hz in the high band. Details of the proposed antenna array are described. The simulated, measured, and calculated results are presented.     

Al-5.4Zn-2.6Mg-1.4Cu合金板材的低周疲劳行为

进行Al-5.4Zn-2.6Mg-1.4Cu合金板材的室温低周疲劳实验,对比研究了轴向平行于轧制方向(RD方向)和垂直于轧制方向(TD方向)试样的低周疲劳行为。结果表明：对于0.4%~0.8%的外加总应变幅,RD和TD方向合金试样的循环应力响应行为均呈现出循环稳定;对于相同的外加总应变幅,TD方向合金的循环应力幅值高于RD方向,而RD方向合金的疲劳寿命高于TD方向。对于RD和TD方向,Al-5.4Zn-2.6Mg-1.4Cu合金的塑性应变幅、弹性应变幅与载荷反向周次均呈线性关系。在低周疲劳加载条件下,裂纹在疲劳试样的自由表面以穿晶方式萌生和扩展。     

60 GHz无线收发实验平台的探究

详细介绍了一种60 GHz无线收发实验平台设计方案,由改进后的NI USRP(收发模块)、NetFPGA(数据处理模块)和PC(主控模块)组成,NI USRP与NetFPGA通过吉比特网口连接,NetFPGA依靠PCI与PC连接,实验平台工作在Linux系统上,并辅以LabVIEW做编程和测试分析,能实现1 Gbit/s以上的理论传输速率.该实验平台方案的收发模块和数据处理模块均可编程,Linux通过PCI对数据流进行捕获、分类、限速等操作,整个平台具有较好的开放性和拓展性,为进一步研究60 GHz通信中的信道建模、时隙分析、多址接入算法等问题提供了便利.     

Research on human blockage effect for indoor 26 GHz mm-wave communications

Based on 26 GHz indoor channel measurements, the blockage attenuation of human bodies was investigated. 2-ray and 4-ray human blockage models were proposed by calculation of the Vogler's multiple knife-edge diffraction field. Results show that 4-ray model fits quite well with measurement data. Human block attenuations are slightly bigger with 1 GHz than with 500 MHz bandwidth. In the blockage measurement of one person moving along the connec-tion line between the transmitter (TX) and receiver (RX), the smallest attenuation is found when the person is located at the middle of the connection line, and the biggest attenuation is observed when the person is nearest from the RX position. In the blockage measurements by multiple human bodies, the attenuation is bigger in the cases which the persons cross the TX-RX connection line with their front faces directed to the horn aperture at the RX than the cases with their lat-eral faces directed to the RX horn aperture. The blockage attenuation is larger with the increase of person numbers, about 5～8 dB more attenuation per person. The results can be used for design of mm-wave 26 GHz indoor communi-cations systems.     

室外微蜂窝小区3.5GHz 电波传播特性仿真和分析

射线跟踪方法是研究室外微蜂窝小区电波传播的有效方法。基于入射及反弹射线法/ 镜像法对室外微小区环境中3. 5GHz 电波传播的路径损耗进行了仿真和分析,仿真结果与文献所给的结果一致性良好,验证了该 方法的正确性。提出了一种新型的射线管判收方法,可有效判断到达接收机的所有射线管。分析了仿真中得到的接收功率、均方根时延扩展、波达方向等传播参数,并比较了视距传播(LOS)和非视距传播(NLOS)的传播特性,这些分析结果可为3. 5GHz 频段无线通信系统的覆盖提供相应的理论依据。     

5G 2.6 GHz与700 MHz频段基站天线建设策略

针对中国移动基站天馈"两多一快"特点及面临的天面租金贵、资源紧张挑战,提出统筹考虑制式频段、采用多频段多端口独立电调天线进行天面整合的天馈建设总体思路.确定以单小区2天面为主的天面目标,"有源、无源分割"、"TDD、FDD分割"的天馈整合原则.统筹考虑5G 2.6 GHz与700 MHz,结合后续5G建设节奏,确定4个...     

采用balun低噪声放大器的5GHz 7.2-dB NF低功耗直接转换接收机前端电路

A 5GHz low power direct conversion receiver radio frequency front-end with balun LNA is presented. A hybrid common gate and common source structure balun LNA is adopted, and the capacitive cross-coupling technique is used to reduce the noise contribution of the common source transistor. To obtain low 1/f noise and high linearity, a current mode passive mixer is preferred and realized. A current mode switching scheme can switch between high and low gain modes, and meanwhile it can not only perform good linearity but save power consumption at low gain mode. The front-end chip is manufactured on a 0.13-μm CMOS process and occupies an active chip area of 1.2 mm². It achieves 35 dB conversion gain across 4.9-5.1 GHz, a noise figure of 7.2 dB and an IIP3 of -16.8 dBm, while consuming 28.4 mA from a 1.2 V power supply at high gain mode. Its conversion gain is 13 dB with an IIP3 of 5.2 dBm and consumes 21.5 mA at low gain mode.     

基于OFDM无线通信系统的线性回归频偏估计算法

为了适应 60 GHz新型 WiFi 对频偏同步的要求, 提出了一种基于 IEEE802.11ad - 2012 修正案系统 的 线性回归频偏估计 (LROE)算法 。 算法将接收到的前导序列与本地序列进行互相关运 算,然后提取 互相关 值的 相位角进行线性回归计算 , 估计出频偏值。 从理论 推导了算法在高斯信道和多径信道下 的 抗噪声 和 抗多径 性能。 在 多径 信道仿真中, 本算法 的频偏 估计精度优于传统自相关算法 3个 数量级, 满足了系统 对高精度频偏估计的要求。 在全系统仿真中,对比研究了本算法和自相关算法对系统 误比特率(BER)性能 的影响, 并与无频偏对照组仿真进行对比。 LROE 算法的 BER 明显优于自相关算法。 仿真研究表明, LROE 算法基 本消除了频偏对系统BER的影响, 其性能 达到了无频偏 系统 的效果 ,达到了 60GHz 系统对频偏同步的 要求。