高速MCM布线网互连和封装效应的计算机仿真

本文针对高速MCM布线网中由互连和封装引起的寄生效应提出了进行计算机仿真的方法 .此方法以兰召斯Pade逼近算法 (PVL)为基础 ,综合了部分元等效电路的三维模型 ,微分求积法的互连线宏模型 ,求解包含通孔、多导体互连线和集总元件组成的复杂线网对高速脉冲信号的响应 .为分析高速MCM设计中的电特性问题提供了高效的工具 .

基于Mesh结构的电源地布线网优化设计

提出了一种优化Mesh结构电源 地布线网的快速算法,使电源 地线网在可靠性约束条件下,通过调整线段的长度和宽度,布线面积达到最小。其基本思想是将约束条件下的非线性规划问题转化为线性规划问题,得到所需的线段长度和宽度。

论布线网上的电气保护

介绍电浪涌的危害在布线网上的几种途径及应在建筑物内哪些地方采取电气保护，保护的原理及相关的器件。

综合布线网热烈拥抱全波光纤

1000MHz频率运算计算机推广应用，廉价的1．3um波长工作的VCSEL(垂直空腔表面发射激光器)的商用将综合布线网提升到了10Gb／s的高水平。随着FTTH(光纤到户)的逐步发展，接入网的瓶颈将不复存在。

用于两端线网布线的蚁群系统方法

提出一种基于蚁群系统的两端线网布线方法 .对于给定的布线平面 ,首先根据障碍情况构造了包含最短路径信息的强连接图 ,建立初始气味矩阵 ,然后使用蚁群算法搜寻目标路径 ,直到求出优化解 .

基于遗传算法的两端线网布线方法

对于给定的布线平面,基于遗传算法的两端线网布线方法首先根据障碍情况对布线平面进行网格化,然后对网格进行编号,用一系列网格序号的有序排列来表示两端点的布线路径,以多条布线路径组成的群体作为优化搜索基础,最后采用遗传算法对此群体进行遗传操作,得到两端线网的最短路径。

基于点线面层次分析法定制公交线网布局

在借鉴国内外相关经验及理论的基础上,运用点线面层次分析法研究了定制公交线网布局,并进行了实例分析,为促进定制公交系统的快速发展提供了理论方法.

多芯片组件中时钟线无时延偏差的改进四通孔(v4R)算法

由于多芯片组件(MCM)布线中所使用的四通孔(v4R)算法在时钟线网布线中不考虑其无时延偏差的特殊布线要求,会使同步功能失控.针对这一缺陷,对MCM的时钟布线提出了一种新的方法.通过引入MMM(MethodofMeansandMedians)方法,使得自动布线结果中,时钟源点到各作用单元的时延相等,从而改进了v4R算法.

A Gridless Router Based on Hierarchical PB Corner Stitching Structure

A multi layer gridless area router is reported.Based on corner stitching,this router adopts tile expansion to explore path for each net.A heuristic method that penalizes nodes deviating from the destination is devised to accelerate the algorithm.Besides,an enhanced interval tree is used to manage the intermediate data structure.In order to improve the completion rate of routing,a new gridless rip up and rerouting algorithm is proposed.The experimental results indicate that the completion rate is improved after the rip up and reroute process and the speed of this algorithm is satisfactory.

Cross Point Assignment Algorithm Under Consideration of Very Long Nets

A cross point assignment algorithm is proposed under consideration of very long nets (LCPA).It is to consider not only the cost of connection between cross points and pins and the exclusive cost among cross points on the boundary of a global routing cell,but also the cost of displacement among cross points of the same net.The experiment results show that the quality and speed in the following detailed routing are improved obviously,especially for very long nets.

Optimal distributed resource allocation in a wireless sensor network for control systems

Wireless technology is applied increasingly in networked control systems. A new form of wireless network called wireless sensor network can bring control systems some advantages, such as flexibility and feasibility of network deployment at low costs, while it also raises some new challenges. First, the communication resources shared by all the control loops are limited. Second, the wireless and multi-hop character of sensor network makes the resources scheduling more difficult. Thus, how to effectively allocate the limited communication resources for those control loops is an important problem. In this paper, this problem is formulated as an optimal sampling frequency assignment problem, where the objective function is to maximize the utility of control systems, subject to channel capacity constraints. Then an iterative distributed algorithm based on local buffer information is proposed. Finally, the simulation results show that the proposed algorithm can effectively allocate the limited communication resource in a distributed way. It can achieve the optimal quality of the control system and adapt to the network load changes.

Performance analysis of IEEE 802.11e EDCA in wireless LANs

In this paper, we propose an analytical model for the performance evaluation of IEEE 802.1 le enhanced distributed channel access （EDCA）. Different from most previous analytical studies based on the saturation assumption, we extend the analytical model to non-saturation conditions. An empty state is introduced into the Markov chain to represent the status of transmission queue being empty. This model can be used to calculate the traffic priority, throughput, and MAC layer delay with various configurations of contention parameters. A detailed simulation is provided to validate the proposed model. With the help of this model, the contention parameters can be configured appropriately to achieve specific quality-of-service （QoS） requirements.

Interference Coordination for Secrecy Enhancement in Random Wireless Networks

The co-channel interference modeling is vital for evaluating the secrecy performance in random wireless networks,where the legitimate nodes and eavesdroppers are randomly distributed.In this paper,a new interference model is proposed from the userdominant perspective.The model can provide a better analytical assessment of secrecy performance with interference coordination for the presence of eavesdroppers.The typical legitimate is assumed to be located at the origin,and chooses the closest base station(BS) as its serving BS.The field of interferers is obtained by excluding the desired BSs(including the serving BS and its cooperative BS(s)).In contract with the exiting interference model,it is assumed that desired BSs and interferers belong to the same Poisson Point Process(PPP),and eavesdroppers are distributed according to another independent PPP.Based on this model,the average secrecy transmission capacity is derived in simply analytical forms with interference coordination.Analysis and simulation results show that the secrecy performance can be significantly enhanced by exploiting interference coordination.Furthermore,the average secrecy transmission capacity increases with increasing number of cooperative BSs.

On the Backlog and Delay Distributions of Primary and Secondary Users in a Cognitive Radio Network

In a cognitive radio network, the secondary users can use the spectrum holes when the primary users do not utilize the spectrum, but they must vacant the spectrum when the primary users need to transmit data on the spectrum. In other words, the primary users have higher priority over the secondary users. In this paper, backlog and delay distribution bounds for both primary users and secondary users are obtained. The analysis is based on stochastic network calculus, for which, stochastic service curves are t-n-st derived for both primary users and secondary users, and the network calculus independent case analysis approach is used to find the distribution bounds. Numerical results and simulation results are also presented and discussed.

A Distributed Online Custom System for Knitted Sweater

A new application of Sun ONE architecture — an online custom system for Knitted Sweaters is presented, which links sweater design, manufacturing and sales in different places to share information through the Internet.The framework and characteristics of J2EE and Sun ONE are analyzed. Having studied the requirements of the online custom system for knitted sweaters, the paper presents a detailed and original system design based on J2EE technology and Web Services. This paper also gives descriptions on how to assemble and deploy the whole system under the Sun ONE architecture.

A Frameless Network Architecture for the Way Forward of C-RAN

The key technologies involved in the evolution of the Cloud-based Radio Access Network(C-RAN) are discussed in this paper. Taking the Frameless Network Architecture(FNA) as a starting point, a cell-lessbased network topology for a multi-tier Heterogeneous Network(Het Net) and ultra-dense network is proposed. The FNA network topology modeling is researched with centralized processing and distributed antenna deployments. The Antenna Element(AE) is released as a new dimensional radio resource that is included in the centralized Radio Resource Management(RRM) processes. This contributes to the on-demand user-centric serving-set associations with cell-edge effect elimination. The Control Plane(CP) and User Plane(UP) separation and adaptation are introduced for energy efficiency improvements. The centralized RRM and different optimization goals are discussed for fully exploring the merits from the centralized computing of C-RAN. Considering the complexity, near-optimal approaches for specific users' Quality-of-Service(Qo S) requirements are addressed. Finally, based on the research highlighted above, the way forward of C-RAN evolution is discussed.

Performance Improvement of Distributed Coordination Function in IEEE 802.11 Wireless LAN

This paper proposes a modification to distributed coordination function （DCF） to improve the channel utilization in IEEE 802.11 wireless local area networks （ WLANs）. In the modified DCF, when a station has contended for the channel, it may transmit multiple data frames continuously to the same destination, which is called transmission burst（TB）. When the maximum number of data packets transmitted continuously in a TB is set to be 2, the performance is expected to be the best. The theoretical analysis and simulation results show that compared with the standard DCF, the modified DCF can increase the throughput and decrease the delay of the WLAN, and the modification does not introduce any additional control overhead.

Distributed Power Control Based on Linear Quadratic Optimal Controller for Cognitive Radio Network

We propose a distributed closedloop power control scheme for a cognitive radio network(CRN) based on our developed state space model of the CRN. The whole power control process is separated into outer control loop and inner control loop in order to solve different problem. In outer loop, the interference temperature(IT) constraint is transformed to a performance index minimized by a state feedback controller to obtain an appropriate target signal to interference plus noise ratio(SINR) of secondary user(SU). For ideal channel model and random time-varying channel model, our designed controller is a linear quadratic regulator(LQR) and a linear quadratic Gaussian(LQG) regulator respectively. While in inner loop, SU controls its transmit power to make the instantaneous SINR track the corresponding target and ensure the IT constraint under the limited threshold. The closed-loop stability of the CRN is proved and the performance of proposed control scheme is presented by computer simulations, which shows that this scheme can effectively guarantee both the requirement of SINR and IT constraint for all SUs.

Distributed multichannel medium access control protocol without common control channel for single-hop cognitive radio networks

A novel distributed cognitive radio multichannel medium access protocol without common control channel was proposed.The protocol divided a transmission interval into two parts for exchanging control information and data,respectively.In addition to evaluating system saturation throughput of the proposed protocol,a three-dimensional multi channel Markov chain model to describe the sate of the cognitive users (CUs) in dynamic spectrum access was presented.The proposed analysis was applied to the packet transmission schemes employed by the basic,RTS/CTS access mechanism adopted in the normal IEEE 802.11.Analyzing the advantage of the two methods,a hybrid access mechanism was proposed to improve the system throughput.The simulation results show that the experiment results are close to the value computed by the model (less than 5%),and the proposed protocol significantly improves the performance of the system throughput by borrowing the licensed spectrum.By analyzing the dependence of throughput on system parameters,hybrid mechanism dynamically selecting access mechanism can maintain high throughput.

Distributed Low-Complexity Channel Assignment for Opportunistic Routing

Opportunistic Routing (OR) involves multiple forwarding candidates to relay packets by taking advantage of the broadcast nature and multi-user diversity of a wireless medium. Compared with Traditional Routing (TR), OR is more suitable in the case of an unreliable wireless link and can evidently improve the end-to-end throughput of Wireless Mesh Networks (WMNs). In this paper, we focus on OR in Multi-Radio Multi-Channel WMNs (MRMC-WMNs). This problem has not been well examined and is considerably more challenging than the OR in single-radio wireless networks considered in the existing literature. First, we validate the advantage of OR in MRMC-WMNs. Second, we propose Low-complexity Channel Assignment for Opportunistic Routing (LcCAOR), which assigns channels to flows according to the interference state of every node. Third, we implement the LcCOAR in a fully distributed manner. The simulation result shows that compared with OR in Single-Radio Single-Channel WMNs (SRSC-WMNs), the proposed OR can significantly enhance the throughput to 87.11% and 100.3% in grid and tree WMNs, respectively.