基于FPGA的光互连网络技术研究与性能分析

研究了基于Xilinx Virtex-5 FPGA的光互连网络技术,通过FPGA板内的高速串行收发器连接SFP光收发模块,实现高速串行数据收发,每通道的传输速率达到3.125Gb/s,提出并实现了基于FPGA的四节点单向环形光互连网络.在ISE设计环境下,设计了基于两块FPGA板的FFT运算应用和基于四块FPGA板的具有随机消息分布特性的网络应用,完成了光互连网络的性能测试分析.     

光在一维随机分布光子晶体中的传播

用特征矩阵法计算了光波在一维随机分布的光子晶体中的传播规律,与周期性结构相比较,在此种结构的光子晶体中带隙结构几乎消失,光波透射率与随机度、频率、介质层数均有关。     

Soft error susceptibility mapping of DRAMs using a high-energy nuclear microprobe

Soft errors in 16 Mbit dynamic random access memories (DRAMs) have been investigated using proton microprobes at 400 keV with a spot size of 1 × 1 μm². The newly developed susceptibility mapping can reveal the correlation between the particle hit-position position and the susceptibility to soft errors in a DRAM. The cell-mode soft-errors were found to take place by the incidence of ions within 6 μm around a monitored cell. These errors would be induced by minority carrier diffusion in a lateral direction. This result manifests the possibility of multiple-bit errors by the incidence of an energetic particle.     

Preparation of (Pb0.88La0.12)TiO3 thin films for dynamic random access memory by low pressure-metalorganic chemical vapor deposition

La-modified lead titanate (PLT) thin films were prepared by hot-wall type low pressure-metalorganic chemical vapor deposition method. Pb(dpm)₂, La(dpm)₃, and titanium tetraisopropoxide were used as source materials. The films were deposited at 500°C under the low pressure of 1000 mTorr and then annealed at 650°C for 10 min in oxygen ambient. Sputter-deposited platinum electrodes and 180 nm thick PLT thin films were employed to form MIM capacitors with the best combination of high charge storage density (26.7 μC/cm² at 3V) and low leakage current density (1.5 × 10^-7 A/cm² at 3V). The measured dielectric constant and dielectric loss were 1000∼1200 and 0.06∼0.07 at zero bias and 100 kHz, respectively.     

一维随机粗糙表面散射特征的数值分析

本文在Ｋｉｒｃｈｈｏｆｆ近似基础上，利用数值积分方法分析了一维随机粗糙表面的散射特征。结果显示随着粗糙度的增大，单次散射峰值由连续地向后向移动，其强度不断降低。峰值宽度增加。在一个较窄的粗糙度范围内，散射场对称于表面法线呈近似余弦分布而接近于理想朗伯体。当粗糙度超过这一范围时，散射峰值将由线向后向移动，并在粗糙度很大时稳定在后向附近。     

关于离散随机变量熵的一个上界

本文分析了离散随机变量熵与方差及有关微分熵的某种关系，给出了离散随机变量熵的一个上界，改进了Ｔ．Ｍ．Ｃｏｖｅｒ与Ｊ．Ａ．Ｔｈｏｍａｓ关于离散熵的上界的已有结果［１］，并以图和表的方式举出一些实例加以比较。     

同位协同随机建模在储层预测中的应用

采用同位协同随机建模技术,以反映储层含油性的电阻率测井参数为主变量,以地震波阻抗为协变量,对储集层的合油砂岩厚度进行了预测。根据大庆葡南油田葡333区块有效储层下限的解释标准,对电阻率随机模拟得到的多个实现进行解释,得到各实现的含油砂岩厚度,并以10m含油砂岩厚度为风险门槛值分析了该区钻井风险性。新、老钻井的钻遇情况分析表明,应用序贯高斯同位协同地震属性数据的模拟方法进行储层预测的精度较高,利用多个随机模拟实现的差异性进行预测结果的风险性评价可以有效地降低钻井风险。     

Modeling and performance analysis of VI‐CRA: A congestion control algorithm for vehicular networks

This study proposes a Vehicle ID‐based CAM Rate Adaptation (VI‐CRA) algorithm for beacon messages in the vehicular network. Foremost, an improved vehicle ID–based analytical model is proposed at the MAC layer of vehicular network. The model weighs the random back‐off number chosen by vehicles participating in the back‐off process, with the vehicle ID incorporated in their respective CAMs. This eventually leads to the selection of a vehicle ID–based random back‐off number, minimizing the probability of collision due to same back‐off number selection. It is worth noting that the improved analytical model outperforms the existing works in terms of average packet delay since only one fourth of the contention window size is used throughout the simulation. To enhance the performance of the analytical model, the paper incorporates a congestion control algorithm, by adapting the rate of CAM broadcast over the control channel. The algorithm is designed considering a wide range of scenarios, ranging from nonsaturated to extremely saturated network (in terms of collision probability) and sparsely distributed to teemed network (in terms of vehicular density). For better analyses of simulation results, the algorithm is applied over different vehicle ID–based back‐off numbers. Simulation results for all the back‐off numbers show that vehicle ID–based CAM rate adaptation algorithm performs better than the traditional fixed CAM rate IEEE 802.11p, even at high vehicular density.     

Reliable M2M/IoT data delivery from FANETs via satellite

The use of unmanned aerial vehicles (UAVs) is rising in several application fields. This work deals with the communication challenges in UAV swarms, or flying ad hoc network (FANET), when taking into account non–line‐of‐sight scenarios. The use of satellites is a necessity in such operating conditions; thus, this work provides architectural considerations and performance assessments when several (FANETs) share an uplink random access satellite channel, fed with M2M/IoT traffic generated from on‐board sensors, to be reliably delivered to a remote ground destination.     

Dual symbol optimization‐based partial transmit sequence technique for PAPR reduction in WOLA‐OFDM waveform

Weighted overlap and add‐orthogonal frequency division multiplexing (WOLA‐OFDM) is a new waveform proposed recently for meeting the requirements of fifth generation (5G) telecommunication standards. In spite of being a serious 5G waveform candidate, WOLA‐OFDM is exposed to the problem of high peak to average power ratio (PAPR) similar to the other waveforms in which multicarrier transmission strategy is employed. Due to the overlapping nature of WOLA‐OFDM waveform, where the extension of the current symbol is overlapped with the extension of the previous symbol, it will not be efficient to apply conventional PTS (C‐PTS) directly to the WOLA‐OFDM waveform. Therefore, in this paper, we propose dual symbol optimization‐based partial transmit sequence (DSO‐PTS) technique for PAPR reduction in WOLA‐OFDM waveform. In our proposed technique, two adjacent symbols are jointly considered when searching for the optimal data block with minimum PAPR unlike the C‐PTS where the adjacent symbols are optimized individually. In the simulations, our proposed DSO‐PTS technique, C‐PTS, and GreenOFDM that is developed recently by modifying the conventional selective mapping (SLM) method are compared with each other with regard to PAPR reduction performance for different search numbers (SNs). In addition, the effects of DSO‐PTS, C‐PTS, and GreenOFDM on the amount of out of band (OOB) radiation in the power spectral density (PSD) graph of WOLA‐OFDM employing solid state power amplifier (SSPA) is measured for different SNs and input back off (IBO) values. According to the simulation results, our proposed DSO‐PTS technique clearly demonstrates a superior PAPR reduction and PSD performance.