An Analytical Approach for Performance Evaluation of Bit-Patterned Media Channels

In this work, a new analytical approach is used to evaluate the error performance of bit-patterned media (BPM) magnetic recording channels that employ one-dimensional (1D) and two-dimensional (2D) generalized partial response (GPR) equalizers to combat the significant inter-track interference (ITI) expected in BPM magnetic recording systems. The probability density function of ITI is obtained analytically and is used to estimate the bit error rate (BER) from the Viterbi detector. The proposed method takes into account most of the important factors affecting the BER such as ITI, un-equalized intersymbol interference (ISI), colored noise and the distance and the multiplicity of error events. In this work, it is shown that for 1D channels, modeling ITI and un-equalized ISI by Gaussian PDFs leads to inaccurate BERs and that the non-Gaussian distribution of the ITI and un-equalized ISI must be taken into account for more accurate BER estimates. This method provides fast and accurate estimates of BERs for moderate to high signal-to-noise ratios (SNRs). By using this analytical method, time-consuming numerical simulations for error performance evaluation can be avoided.     

TD-SCDMA系统终端中的GMM功能实体研究

移动性管理(MM,Mobility Management)是层3的一个子层,它主要完成与用户的移动性相关的一些功能。根据业务的分域划分,MM 子层被分为支持 CS 模式的 MM 实体和支持 PS 模式的 GMM 实体。本文通过对 GMM 一般过程和特殊过程的描述,介绍了 TD-SCDMA 系统终端 GMM 实体的功能及其实现过程。     

移动计算用户界面可用性评估的眼动方法

 为了降低传统可用性评估方法中的主观影响和误差,本文应用眼动跟踪技术分析人机交互过程中的认知情况,提出移动计算用户界面可用性评估方法.该方法选取凝视时间、凝视数目、感兴趣区转移频次矩阵等眼动指标,并结合交互任务与自顶向下的视觉认知机制对界面进行分析,建立可用性评估模型,考察视觉搜索和信息加工等认知效率,进而为界面设计优化提供指导.以手机用户界面为对象的评估实例表明,该方法可有效分析界面认知内因,获取可用性问题清单,与用户主观评估保持较高一致性,验证了其实用性与有效性.     

TD-SCDMA系统终端中的GMM功能实体研究

移动性管理(MM,MobilityManagement)是层3的一个子层,它主要完成与用户的移动性相关的一些功能。根据业务的分域划分,MM子层被分为支持CS模式的MM实体和支持PS模式的GMM实体。本文通过对GMM一般过程和特殊过程的描述,介绍了TD-SCDMA系统终端GMM实体的功能及其实现过程。     

Performance Evaluation of Bluetooth Polling Schemes: An Analytical Approach

In the recent years, many polling schemes for Bluetooth networks have been proposed and evaluated. To the authors knowledge, however, analysis has been carried out mainly through computer simulations and, up to now, no mathematical treatment of this topic has been presented. In this paper, we propose an analytical framework for performance evaluation of polling algorithms in Bluetooth piconets. The analysis is carried out by resorting to an effective and simple mathematical method, called Equilibrium Point Analysis. The system is modelled as a multidimensional finite Markov chain and performance metrics are evaluated at the equilibrium state. The analysis is focused on three classical polling schemes, namely Pure Round Robin, Gated Round Robin and Exhaustive Round Robin, which are compared in terms of packet delay, channel utilization, and fairness among users. Both analytical and simulation results are presented for three relevant scenarios, in order to validate the accuracy of the analysis proposed.     

应变硅电子迁移率解析模型

提出了一个应变硅沟道电子迁移率解析模型.模型以应变张量为对象研究应变硅沟道电子迁移率,因此与工艺相独立;适用于施加双轴应力及<100>/<110>方向单轴应力,沟道方向为<100>/<110>的器件;易于嵌入常用仿真工具中.     

应变硅电子迁移率解析模型

提出了一个应变硅沟道电子迁移率解析模型.模型以应变张量为对象研究应变硅沟道电子迁移率,因此与工艺相独立;适用于施加双轴应力及<100>/<110>方向单轴应力,沟道方向为<100>/<110>的器件;易于嵌入常用仿真工具中.     

An Analytical Study of Control Plane Failures Impact on GMPLS Ring Optical Networks

Within the generalized multi-protocol label switching (GMPLS), link management protocol (LMP) has been proposed to maintain the connectivity of the out-of-fiber control plane. In this paper, we analytically quantify the impact of control plane link failures on whole network performance. Then, we use the obtained results to suggest the keep-alive interval for LMP, introducing the least overhead to the control network while keeping an acceptable network grade of service (GoS).     

Phosphorus: 光子网格的分布式控制平面技术

G2MPLS is a Network Control Plane (NCP) architecture that implements the concept of Grid Network Services (GNS) required for implementing photonic Grids. It provides part of the functionalities related to the selection, co allocation and maintenance of both Grid and network resources through a set of seamless procedures at the user to network and inter domain boundaries. G2MPLS main features and procedures are presented in this document, as well as the considerations to deploy it and facilitate its dissemination.     

A New Control Approach for a Robotic Walking Support System in Adapting User Characteristics

This paper proposes a new control approach for a robotic walking support system to adapt a user's controlling characteristic. The control approach will be implemented by changing the kinematic structure of the robotic walking support system based on a variable center of rotation. This new control approach aims to help users who have difficulties in controlling their walking support system. In this study, we have a training stage to evaluate and adapt user's controlling characteristics. This will be implemented by allowing the user to follow some training paths. In the event a large path error occurs, a learning algorithm will vary the center of rotation of the support system until the user can successfully follow the training path. The relationship between the user intent in the form of applied force/torque and the new center of rotation will be taken by considering several training paths. This relationship will be used in actual control of the robotic walking support system. Experimentation and evaluation are presented to show the validity of the proposed control algorithm     

An End-To-End Approach for Transparent Mobility Across Heterogeneous Wireless Networks

With the advent of a myriad of wireless networking technologies, a mobile host today can potentially be equipped with multiple wireless interfaces that have access to different wireless networks. It is widely perceived that future generation wireless networks will exhibit a similar trend in supporting a large variety of heterogeneous wireless access technologies that a mobile host can choose from. In this paper, we consider such a multi-homed mobile host and propose an end-to-end solution that enables the seamless use of heterogeneous wireless access technologies. The unique features of the proposed solution include: (i) a purely end-to-end approach to handle host mobility that requires no support from the underlying network infrastructure, (ii) seamless vertical handoffs when the mobile host migrates from one access network to another, (iii) ability to support different congestion control schemes for a live connection traversing different interfaces, and (iv) effective bandwidth aggregation when the mobile host has simultaneous access to multiple networks. We present the design and details of the proposed approach, and evaluate its performance through simulations and real-life field experiments.     

WiQoSM: An Integrated QoS-Aware Mobility and User Behavior Model for Wireless Data Networks

Modeling mobility and user behavior is of fundamental importance in testing the performance of protocols for wireless data networks. Although several models have been proposed in the literature, none of them can at the same time capture important features such as geographical mobility, user-generated traffic, and the wireless technology at hand. When collectively considered, these three aspects determine the user-perceived quality-of-service (QoS) level, which, in turn, might have an influence on the mobility of those users (we call them QoS-driven users) who do not display constrained mobility patterns, but they can decide to move to less congested areas of the network in case their perceived QoS level becomes unacceptable. In this paper, we introduce the Wireless QoS-aware Mobility (WiQoSM) model, which collectively considers all of the above mentioned aspects of wireless data networks. WiQoSM is composed of 1) a user mobility model, 2) a user traffic model, 3) a wireless technology model, and 4) a QoS model. Components 1,2, and 3 provide input to the QoS model, which, in turn, can influence the mobility behavior of QoS-driven users. WiQoSM is very simple to use and configure and can be used to generate user and traffic traces at the access points (APs) composing a wireless data network. WiQoSM is shown to be able to generate traces that resemble statistical features observed in traces extracted from real-world wireless local area network (WLAN) deployments. Furthermore, WiQoSM has the nice feature of allowing the fine tuning of a disjoint set of parameters in order to influence different statistical properties of the generated traces and of providing the network designer with a high degree of flexibility in choosing network parameters such as the number of users and APs, wireless channel technology, traffic mix, and so on. Given the above features, WiQoSM can be a valuable tool in the simulation of wireless data network protocols.     

TD-SCDMA系统终端CC实体研究

呼叫控制(CC)实体是CM子层功能实体之一,是整个CM层的核心,主要完成CS域基本的呼叫管理。通过对呼叫建立和呼叫清除过程的描述,介绍了TD-SCDMA系统终端CC实体的功能及实现过程。     

研究混沌系统同步问题的一种解析方法

本文利用解析方法研究Ｌｏｒｅｎｚ和Ｒｏｓｓｌｅｒ两种混沌系统中的一驱动二响应和二驱动一响应过程。得到了在各种中实现同步的条件。其结论与以前文献中的结论一致,但更加普适。     

An Evaluation Study of Mobility Support in ZigBee Networks

Based on the IEEE 802.15.4 LR-WPAN specification, the ZigBee standard has been proposed to interconnect simple, low rate, and battery powered wireless devices. The deployment of ZigBee networks is expected to facilitate numerous applications, such as home healthcare, medical monitoring, consumer electronics, and environmental sensors. For many of the envisioned applications, device mobility is unavoidable and must be accommodated. Thus, providing ubiquitous connections to/from a mobile device is crucial for various future ZigBee applications. Knowledge of how nodal mobility affects the ZigBee routing protocol is important, but the lack of ZigBee simulator support has limited the amount of research, evaluation, and development in this area. Thus far, researchers have been unable to analyze and evaluate the impact of mobile applications via extensive simulations. In this paper, our contribution is threefold. First, we present an initial implementation of the ZigBee network layer in NS-2, which will allow further research and development to be conducted in this area. Second, we analyze the adequacy of current provisions for dealing with different mobility cases. Third, we provide a comprehensive set of simulation results that demonstrate the inefficacy of the current standard for handling mobility. Our results show that the ZigBee device plays a significant role in determining the routing performance in mobile scenarios.     

基于混合推理系统挖掘用户访问模式的ILP方法

提出一种结合DL-safe规则挖掘用户访问模式的ILP方法.该方法首先定义基于事件的日志本体,将DL-safe规则和日志本体构建为一个推理过程可判定的混合日志知识库,在此基础上借助ILp的理论和方法学习生成有效用户访问模式.该方法充分利用日志本体中事件问特定的语义关系有效简化了挖掘过程并提高了挖掘效率,为改进站点结构提供更有效的决策.实验结果表明了该方法的可判定性和有效性.     

TD-SCDMA网络建设中Iu接口用户平面假活现象的解决方法

为了满足用户对网络性能不断增长的需求,3GPP在R4核心网中引入软交换技术,将移动交换中心（MSC）分成移动交换中心服务器（MSCServer）和媒体网关（MG）,并选择Iu接口作为无线接入网（UTRAN）和核心网（CN）的通用接口。主要讨论了在TD-SCDMA网络建设中Iu接口用户面的假活现象对网络性能的影响,并提出了具体的解决措施,包括增加MSCServer对Iu用户面资源的监测功能。利用SNMP协议在MScServer中检测并向无线网元管理器（WEM）卖时反馈Iu接口用户面状态。最后将该方案以系统补丁的形式,在上海贝尔阿尔卡特实验室TD—SCDMA试验网中进行功能验证与测试。     

mPERSONA: Personalized Portals for the Wireless User: An Agent Approach

The needs of the wireless and mobile user regarding information access and services are quite different than those of the desktop user. This need is not about browsing the Web but about receiving personalized services that are highly sensitive to the immediate environment and requirements of the user. Personalization appears to be the most appropriate solution to this need. It comes into aid by creating personalized portals that are specific for the wireless user, which (a) are focus on the local content and (b) directly tones down factors that break up the functionally of the Internet/wireless services when viewed through wireless devices; factors like the click count, user response time (the choice factor) and the size of the wireless network traffic. In this paper we present a flexible personalization system for the wireless user that takes into consideration user mobility, the local environment and the user and device profile. The system utilizes the various characteristics of mobile agents to support flexibility, scalability, modularity and user mobility. We present metrics appropriate to the wireless environment, and an initial performance evaluation indicating improvement ranging from 33% up to, for certain metrics, 60%.     

p-n结电场分布的一种解析法

本文发展一种求解泊松方程解的电势与电场的超定方程组的新方法,获得p—n结非对称圆柱解下的圆柱结与平面结相匹配的电势与电场分布及椭圆圆柱解下两者相统一的电场分布公式。将两种解与迄今常用的对称圆柱解进行了比较,发现前者更符合实际。     

An Analytical Investigation of Current-Injected Control for Constant-Frequency Switching Regulators

State-space averaging and linearization are applied to current-injected, constant-frequency switching regulators, resulting in a generalized two-loop system representation. The boost regulator is examined in detail to show that, as a theoretical goal, wide-bandwidth, first-order behavior can be achieved with no right-half-plane zeroes. Actual performance may be limited by switching frequency interference considerations.