A noncooperative power control game for multirate CDMA data networks

The authors consider a multirate code-division multiple acess system, in which all users have the same chip rate and vary their data rate by adjusting the processing gain. The receivers are assumed to be implemented using conventional matched filters, whose performance is sensitive to the received power levels. The authors' goal is to maximize the total system throughput by means of power control. A game theoretic approach is adopted. It is shown that for a certain type of pricing function, a unique Nash equilibrium solution exists and it possesses nice global properties. For example, it can be shown that for the optimal solution a high-rate connection should maintain a higher energy per bit than low-rate ones. The asymptotic spectral efficiency is also derived.     

一种基于QoS的无线Mesh网络DSR路由优化算法

无线Mesh网络(Wireless Mesh Network,简称WMN)是一种新型的高容量、高速率的分布式宽带无线网络,是下一代无线网络的关键技术。在综合考虑带宽、传输拥塞、网络吞吐量等方面因素,将博弈论的思想引入动态源路由(Dynamic Source Routing,简称DSR)算法中,提出一种基于博弈论的DSR路由优化算法,经分析与仿真表明,该路由能有效减小时延,提高数据传输效率,提升网络传输的服务质量(Quality of Service,简称QoS)。     

DDN典型故障一例

DDN（Digital Data Network）即数字数据网。由于DDN专线提供点到点的通信,通信保密性强,多被税务、金融等客户采用。为保障全网业务正常,计算机终端的正常与否也是通信保障中的重要环节。     

基于聚合表技术的数据挖掘方法研究

文章通过对聚合表技术的研究和分析，把该技术应用于基于ROLAP的数据挖掘中．既充分发挥了ROLAP方法的优势，又克服了其查询效率低的最大弱点。     

Influence of Photolithography on the Cross-Sectional Shape of Polysiloxane as an Optical Waveguide Material on Printed Circuit Boards

Optical waveguide cross-sectional shapes that deviate from rectangles or squares may cause significant loss of signal. In this study, a photolithography approach was adopted to fabricate waveguides on printed circuit boards, using photo-imageable polysiloxane as a waveguide material. The effects of I-line ultraviolet (UV) lamp exposure, 355-nm Nd:YAG laser direct imaging, and 248-nm excimer laser direct imaging on the cross-sectional shape of waveguides were investigated. For I-line UV lamp exposure, increasing the exposure time could cause changes in the tilt angle of the waveguides from negative (inverted trapezoid) to positive (trapezoid). To obtain rectangular waveguides, the optimum I-line UV lamp exposure time was found to be around 150 s. From the results for 355-nm Nd:YAG laser direct imaging, the width and tilt angle of the waveguides varied with the energy density of the laser beam irradiating the core materials, being controlled by the repetition rate and focus. Lowering the laser energy density could produce waveguides with small widths and tilt angles. Excimer laser direct imaging at 248 nm was found to be unsuitable for waveguide patterning since the core materials could not be cured at this wavelength.     

Z-function convolution in EHV power network electromagnetic transient analysis

Time-convolution in the forms arising in transformation from the frequency-domain to the time-domain has been widely used in the earlier development of electromagnetic transient methods in power systems. Independent work has recently led to new methods based on the z-transform, and the present paper develops methods based on discrete convolution arising from transformation to the time-domain now from the z-plane. The recursive solution sequences to which this leads combines high accuracy with low computing time requirements. Checks and controls in the synthesis of transmission line forward impulse response and surge impedance functions in the z-plane ensure that these are always stable system functions, and that numerical solution procedures which include them have very high inherent stability. The formulations developed are applied to transmission line energization from an equivalent source model, and the electromagnetic transients in short-circuit fault operation. Close comparisons are made between representative solutions from standard time-convolution analysis and from the methods of the present paper.     

Hall effect characterization of LPE HgCdTe P/n heterojunctions

The field and temperature dependence of the Hall coefficient has been used to simultaneously extract information about the p and n layers in very long wave length infrared P/n HgCdTe heterojunctions. The field dependence allows the effects of high mobility electrons to be separated from those of low mobility holes. The higher the magnetic field, the higher the sensitivity to the parameters of the P layer. For a maximum magnetic field of 8000 gauss, the hole sheet concentration must be at least five times the electron sheet concentration to obtain accurate results for the P layer. This criterion is satisfied for typical liquid phase epitaxy (LPE) heterostructures. The analysis determines the hole sheet resistance (concentration times mobility), rather than the hole concentration or mobility separately. Independent knowledge of the P layer thickness and the relationship between hole concentration and resistivity are needed to convert the Hall measurement results to hole concentrations. Analysis of the field-dependent Hall data is complicated by the finding that at least three electrons of different mobilities are needed to fit the field dependence of the Hall coefficient in n-type LPE HgCdTe layers. These results are consistent with previous conclusions that electrons with different mobilities are needed to model bulk n-HgCdTe, and with a range of mobilities in the graded composition interface between the LPE layer and CdTe substrate. Consistent results are obtained for the concentrations and mobilities of the three types of electrons in the n-HgCdTe layer with and without the P layer present. N and P type carrier concentrations are also consistent with dopant concentrations measured by secondary ion mass spectroscopy.     

Concentration-dependent 4I13/2 lifetimes inEr3+-doped fibers and Er3+-doped planar waveguides

We report on the concentration- and pump-dependent lifetimes of the spontaneous emission in Er³⁺-doped fibers and Er³⁺ -doped waveguides. In addition, we measure the concentration dependence of the 550-nm fluorescence due to excited state absorption (ESA)     

Resonance in a superstrate-loaded cylindrical-rectangularmicrostrip structure

The complex resonant frequencies of the cylindrical-rectangular microstrip structure loaded with a dielectric superstrate layer is studied using a rigorous full-wave analysis, and the numerical results are obtained using the Galerkin moment method calculation. The numerical convergence for the selected sinusoidal basis functions with and without the edge singularity condition is also discussed. Numerical results for the dependence of the real and imaginary parts of the complex resonant frequencies on the superstrate permittivity and thickness are calculated and analyzed, and are compared with those obtained for the planar microstrip structure     

SONET implementation

The status of the synchronous optical network (SONET) infrastructure development and deployment are examined to see whether or not they meet original expectations. Issues arising from deployment, such as the use of new features and the necessary support from operations systems, and future directions of SONET are discussed. These future trends include digital cross connect systems (DCSs), SONET ring architectures, and hybrid ring-DCS networks. New SONET services are also discussed