One traditional view of how wireless networks evolve is of a continuous, inevitable progres- sion to higher link speeds, combined with greater mobility over wider areas. This standpoint certainly captures the development from first and second generation cellular systems focused on voice support, and the early short-range wireless data networks, through to today’s 3G cellular and mobile broadband systems; there is every confidence that the trend will continue some way into the future.
上传时间： 2020-05-26
上传用户：shancjb
Cooperation is not a natural characteristic attributed to humans. The typical human horizon is focused on short-term gains, which might be due to our instinct-driven subconscious occupying a grander importance than we dare to admit [1]. Cooperating with other individuals or entities, however, usually means that short-term losses may translate into long-term gains – something history has proved to hold true but humans for some reason rarely ever understand.
标签： Communications Cooperative
上传时间： 2020-05-27
上传用户：shancjb
Fixed-mobile.convergence.and.voice-data.networks.have.merged.next-gen- eration,.value-added.applications.and.integrated.multimedia.services,.com- bining. Web. browsing,. instant. messaging,. presence,. voice. over. IP,. video. conferencing,. application. sharing,. telephony,. unified. messaging,. multi- media.content.delivery,.etc..on.top.of.different.network.technologies..The. convergence.of.the.communications.networks.is.motivated.by.the.need.to. support.many.forms.of.digital.traffic.as.well.as.to.amortize.implementation. and.operational.costs.of.the.underlying.networks..Historically,.the.approach. to. build. and. deploy. multimedia. services. has. focused. upon. single-point. solutions..
标签： Multimedia Subsystem Handbook IMS IP
上传时间： 2020-05-27
上传用户：shancjb
Part I provides a compact survey on classical stochastic geometry models. The basic models defined in this part will be used and extended throughout the whole monograph, and in particular to SINR based models. Note however that these classical stochastic models can be used in a variety of contexts which go far beyond the modeling of wireless networks. Chapter 1 reviews the definition and basic properties of Poisson point processes in Euclidean space. We review key operations on Poisson point processes (thinning, superposition, displacement) as well as key formulas like Campbell’s formula. Chapter 2 is focused on properties of the spatial shot-noise process: its continuity properties, its Laplace transform, its moments etc. Both additive and max shot-noise processes are studied. Chapter 3 bears on coverage processes, and in particular on the Boolean model. Its basic coverage characteristics are reviewed. We also give a brief account of its percolation properties. Chapter 4 studies random tessellations; the main focus is on Poisson–Voronoi tessellations and cells. We also discuss various random objects associated with bivariate point processes such as the set of points of the first point process that fall in a Voronoi cell w.r.t. the second point process.
标签： Stochastic Geometry Networks Wireless Volume and
上传时间： 2020-06-01
上传用户：shancjb
During the past three decades, the world has seen signifi cant changes in the telecom- munications industry. There has been rapid growth in wireless communications, as seen by large expansion in mobile systems. Wireless communications have moved from fi rst-generation (1G) systems primarily focused on voice communications to third-generation (3G) systems dealing with Internet connectivity and multi-media applications. The fourth-generation (4G) systems will be designed to connect wire- less personal area networks (WPANs), wireless local area networks (WLANs) and wireless wide-area networks (WWANs).
标签： Communications Networking Wireless
上传时间： 2020-06-01
上传用户：shancjb
This book is focused on designing and developing Representational State Transfer (REST) platforms in Rails. REST is the architectural style of the Web, consisting of a set of constraints that, applied to components, connectors, and data elements, constitute the wider distributed hypermedia system that we know today: the World Wide Web. There are a few good reasons why it makes more sense to build platforms instead of just products or applications. Platforms are like ecosystems interconnecting different applications, services, users, developers, and partners. Platforms foster innovation through the inputs of their direct collaborators. By providing application programming interfaces (APIs) and software development kits (SDKs), platforms are more customer driven.
标签： Development Building RESTful Rails
上传时间： 2020-06-06
上传用户：shancjb
This edition of Digital Image Processing is a major revision of the book. As in the 1977 and 1987 editions by Gonzalez and Wintz, and the 1992, 2002, and 2008 editions by Gonzalez and Woods, this sixth-generation edition was prepared with students and instructors in mind. The principal objectives of the book continue to be to provide an introduction to basic concepts and methodologies applicable to digital image processing, and to develop a foundation that can be used as the basis for further study and research in this field. To achieve these objectives, we focused again on material that we believe is fundamental and whose scope of application is not limited to the solution of specialized problems. The mathematical complexity of the book remains at a level well within the grasp of college seniors and first-year graduate students who have introductory preparation in mathematical analysis, vectors, matrices, probability, statistics, linear systems, and computer programming. The book website provides tutorials to support readers needing a review of this background material
标签： Processing Digital Image
上传时间： 2021-02-20
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为了提高超高频RFID系统中阅读器在低信噪比的情况下仍具有较高的识别能力,提出一种基于FPGA系统结合软件无线电方法实现超高频RFID射频前端电路方案。超高频射频识别系统必须符合EPC Class 1generation 2标准,所设计的电路系统以Xilinx公司的XC6SLX16-2CSG324FPGA芯片为硬件基础,将数字基带调制解调和中频滤波电路在FPGA系统中设计实现,重点阐述了射频前端电路的设计结构、AD/DA转换电路,以及数字滤波器的设计。实验结果表明,所设计的超高频RFID阅读器简化了前端电路系统结构,提升了稳定性,增强了抗干扰能力。该电路系统在信噪比较低的情况下,能够较好地实现915MHz频率的射频接收和发送。In order to improve the reader UHF RFID system still has a higher ability to identify,in the case of low signal-to-noise ratio.The UHF RFID systems must comply with EPC Class 1 generation 2 standard.In this paper,the design of the circuit system based on Xilinx＇s XC6SLX16-2CSG324 FPGA chip,and presents UHF RFID RF front-end circuit with software radio based on FPGA system.Digital baseband modem and IF filter circuit is designed and implemented in the FPGA system,and focused on designing the structure of the RF front-end circuit,AD/DA conversion circuits,and digital filter.Experimental results show that the UHF RFID reader de...
标签： 915mhz 超高频 rfid 阅读 射频 前端 电路 设计
上传时间： 2022-04-17
上传用户：shjgzh
随着科技的发展，人们在日常生活中使用的电器越来越多，电子设备的电磁兼容性（EMC）也越来越重要。所以，人们对电子设备的电磁兼容性的要求也越来越严格，越来越规范。而在市场竞争中，如何降低成本、减少设备体积，是各电子设备制造厂家重点研究的课题。通过对开关电源的EMI滤波电路的类别和相应的技术特点进行分析，设计出一种既能提高性能，又能降低成本的滤波电路。With the development of technology, appliances people use in their daily lives, more and more electronic devices electromagnetic compatibility （ EMC ） has become increasingly important. So, people electromagnetic compatibility requirements of electronic devices have become increasingly stringent, more and more standardized. The competition in the market, how to reduce costs, reduce equipment size, is the subject of the electronic equipment manufacturer focused on research. Through the technical characteristics of the respective category and the EMI filter circuit switching power supply is analyzed both designed to improve a performance of the filter circuit can reduce the cost.
上传时间： 2022-04-23
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近年来，对器件的失效分析已经成为电力电子领域中一个研究热点。本论文基于现代电力电子装置中应用最广的IGBT器件，利用静态测试仪3716，SEM（Scanning Electrom Microscope，扫描电子显微镜）、EDX（Energy Dispersive X-Ray Spectroscopy、能量色散x射线光谱仪）、FIB（focused lon beam，聚焦高子束）切割、TEM（Thermal Emmision Microscope，高精度热成像分析仪）等多种分析手段对模块应用当中失效的1GBT芯片进行电特性分析、芯片解剖并完成失效分析，并基于相应的失效模式提出了封装改进方案。1，对于栅极失效的情况，本论文先经过电特性测试完成预分析，并利用THEMOS分析出栅极漏电流通路，找到最小点并进行失效原因分析，针对相应原因提出改进方案。2，针对开通与关断瞬态过电流失效，采用研磨、划片等手段进行芯片的解剖。并用SEM与EDX对芯片损伤程度进行评估分析，以文献为参考进行失效原因分析，利用saber仿真进行失效原因验证。3，针对通态过电流失效模式，采用解剖分析来评估损伤情况，探究失效原因，并采用电感钳位电路进行实验验证。4，针对过电压失效模式，采用芯片解剖方式来分析失效点以及失效情况，基于文献归纳并总结出传统失效原因，并通过大量实验得出基于封装的失效原因，最后采用saber仿真加以验证。
标签： igbt
上传时间： 2022-06-21
上传用户：1208020161
