Wireless communications has become a field of enormous scientific and economic interest. Recent success stories include 2G and 3G cellular voice and data services (e.g., GSM and UMTS), wireless local area networks (WiFi/IEEE 802.11x), wireless broadband access (wimax/IEEE 802.16x), and digital broadcast systems (DVB, DAB, DRM). On the physical layer side, traditional designs typically assume that the radio channel remains constant for the duration of a data block. However, researchers and system designers are increasingly shifting their attention to channels that may vary within a block. In addition to time dispersion caused by multipath propagation, these rapidly time-varying channels feature frequency dispersion resulting from the Doppler effect. They are, thus, often referred to as being “doubly dispersive.”
标签： Time-Varying Channels
上传时间： 2020-06-01
上传用户：shancjb
Today wireless is becoming the leader in communication choices among users. It is not anymore a backup solution for nomadic travellers but really a newmoodnaturallyusedeverywhereevenwhenthewiredcommunicationsare possible. Many technologies evolve then continuously, changing the telecom- munication world. We talk about wireless local area networks (WLANs), wire- less personal area networks (WPANs), wireless metropolitan area networks (WMANs), wireless wide area networks (WWANs), mobile ad hoc networks (MANETs), wireless sensor networks (WSNs) and mesh networks. Since we can find today a multitude of wireless technologies we decided to group a numberofcomplementarytechnologiesintoonedocumenttomakeiteasierfor areadertounderstandsomeofthetechnicaldetailsofeachmedia.
标签： TM Bluetooth Zigbee Wi-Fi wimax and
上传时间： 2020-06-01
上传用户：shancjb
Notwithstanding its infancy, wireless mesh networking (WMN) is a hot and growing field. Wireless mesh networks began in the military, but have since become of great interest for commercial use in the last decade, both in local area networks and metropolitan area networks. The attractiveness of mesh networks comes from their ability to interconnect either mobile or fixed devices with radio interfaces, to share information dynamically, or simply to extend range through multi-hopping.
标签： Multi-hop Networks wimax WiFi Mesh LTE and
上传时间： 2020-06-01
上传用户：shancjb
所设计的多频段小型化天线结构新颖，性能指标优越，与当前国内外研究的大多数同类天线相比保持较小体积，在多频、宽频工作频段上也保持较强的竞争力。其中所设iMonopole，780MHz-1010MHz和1630MHz3900MHz，在高频频段上的提升相当明显，与大多数同类天线相比提升超过100%，除了覆盖GSM，UMTS，LTE的频段外，还覆盖wimax的频段，为未来5G通信的多频段融合发展提供有力支撑；所设计多频段小型化PIFA天线，工作频段为680MHz980MHz和1665MHz-2755MHz，覆盖GSM，UMTS，LTE所需的所有频段，同时该天线的小型化指标忧异，其辐射贴片部分的尺寸仅为33mm x mm0.8mm，在当前国内外同类天线中具有相当强的竞争力。这两款天线结构简单，加工成本低，十分适用于5G移动通信移动终端中。最后，设计一款超宽带微带天线。所设计的超宽带微带天线利用新型倒置E型槽，获得了超宽带性能，工作频段覆盖27.6GHz-33.2GHz.采用新的债电方式一半圆渐进馈电，不仅可以改善天线的辐射特性，还能降低阻抗匹配的难度，进而一定程度上简化了天线的设计难度。在天线辐射贴片开有圆角矩形槽，大大的改善了天线的阻抗特性，进一步优化了天线的辐射特性，保证了天线在整个烦段内辐射方向图的稳定性。天线加工简单、成本低，非常适用于5G移动通信的大规模组网。
上传时间： 2022-06-20
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5G，第五代移动通信技术，也是4G之后的延伸，目前正在研究中。目前还没有任何电信公司或标准订定组织（像3GPP，wimax论坛及ITU-R）的公开规格或官方文件有提到5G。按照业内初步估计，包括5G在内的未来无线移动网络业务能力的提升将在3个维度上同时进行：1）通过引入新的无线传输技术将资源利用率在4G的基础上提高10倍以上；2）通过引入新的体系结构（如超密集小区结构等）和更加深度的智能化能力将整个系统的吞吐率提高25倍左右；3）进一步挖掘新的频率资源（如高频段、毫米波与可见光等），使未来无线移动通信的频率资源扩展4倍左右.5G有以下特点：1）5G研究在推进技术变革的同时将更加注重用户体验，网络平均吞吐速率、传输时延以及对虚拟现实、3D、交互式游戏等新兴移动业务的支撑能力等将成为衡量5G系统性能的关键指标.2）与传统的移动通信系统理念不同，5G系统研究将不仅仅把点到点的物理层传输与信道编译码等经典技术作为核心目标，而是从更为广泛的多点、多用户、多天线、多小区协作组网作为突破的重点，力求在体系构架上寻求系统性能的大幅度提高.3）室内移动通信业务已占据应用的主导地位，5G室内无线覆盖性能及业务支撑能力将作为系统优先设计目标，从而改变传统移动通信系统“以大范围覆盖为主、兼顾室内"的设计理念.4）高频段频谱资源将更多地应用于5G移动通信系统，但由于受到高频段无线电波穿透能力的限制，无线与有线的融合、光载无线组网等技术将被更为普遍地应用.5）可“软”配置的5G无线网络将成为未来的重要研究方向，运营商可根据业务流量的动态变化实时调整网络资源，有效地降低网络运营的成本和能源的消耗.
上传时间： 2022-06-21
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PrefaceDuring the past years, there has been a quickly rising interest in radio access technologies for providingmobile as well as nomadic and fixed services for voice, video, and data. The difference indesign, implementation, and use between telecom and datacom technologies is also becoming moreblurred. One example is cellular technologies from the telecom world being used for broadband dataand wireless LAN from the datacom world being used for voice-over IP.Today, the most widespread radio access technology for mobile communication is digital cellular,with the number of users passing 5 billion by 2010, which is more than half of the world’s population.It has emerged from early deployments of an expensive voice service for a few car-borne users,to today’s widespread use of mobile-communication devices that provide a range of mobile servicesand often include camera, MP3 player, and PDA functions. With this widespread use and increasinginterest in mobile communication, a continuing evolution ahead is foreseen.This book describes LTE, developed in 3GPP (Third Generation Partnership Project) and providingtrue 4G broadband mobile access, starting from the first version in release 8 and through the continuingevolution to release 10, the latest version of LTE. Release 10, also known as LTE-Advanced,is of particular interest as it is the major technology approved by the ITU as fulfilling the IMTAdvancedrequirements. The description in this book is based on LTE release 10 and thus provides acomplete description of the LTE-Advanced radio access from the bottom up.Chapter 1 gives the background to LTE and its evolution, looking also at the different standardsbodies and organizations involved in the process of defining 4G. It also gives a discussion of the reasonsand driving forces behind the evolution.Chapters 2–6 provide a deeper insight into some of the technologies that are part of LTE and itsevolution. Because of its generic nature, these chapters can be used as a background not only for LTEas described in this book, but also for readers who want to understand the technology behind othersystems, such as WCDMA/HSPA, wimax, and CDMA2000.Chapters 7–17 constitute the main part of the book. As a start, an introductory technical overviewof LTE is given, where the most important technology components are introduced based onthe generic technologies described in previous chapters. The following chapters provide a detaileddescription of the protocol structure, the downlink and uplink transmission schemes, and the associatedmechanisms for scheduling, retransmission and interference handling. Broadcast operation andrelaying are also described. This is followed by a discussion of the spectrum flexibility and the associated
上传时间： 2022-07-08
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VIP专区-嵌入式/单片机编程源码精选合集系列（109）资源包含以下内容：1. 包括汇编和c++编写的万年历.2. FIFO（先进先出队列）通常用于数据的缓存和用于容纳异步信号的频率或相位的差异。本FIFO的实现是利用 双口RAM 和读写地址产生模块来实现的.FIFO的接口信号包括异步的写时钟（wr_clk）和读.3. Analog signals are represented by 64 bit buses. They are converted to real and from real representa.4. 该文件为lpc2106 ARM7在THREDX操作系统下的启动代码.5. 该代码为时钟芯片PCF8563的控制程序.6. 此代码位PIC单片机的PID控温程序.7. threadx技术手册.8. 一个关于fat32系统文件的说明,对了解fat32文件系统系统结构很有用.9. 典型的开发模型有：①瀑布模型(waterfall model)；②渐增模型/演化/迭代(incremental model)；③原型模型(prototype model)；④螺旋模型(spiral m.10. zigbee协议中.11. 三菱FX系列PLC与PC机通过编程口通讯的地址转换软件,非常的使用!.12. 文章讲述了类似于PDOP值的描述整周模糊度精度的指标因子。对于整周模糊度的判断具有重要意义。.13. 讲述了如何对主引导扇区进行备份和恢复.14. LED驱动电路实例。配具体的电路图供大家参考使用.15. Pcb初级教程.16. 嵌入式内存数据库系统eXtremeDB用户指南.17. 对引导区的学驻病毒进行了剖析.18. LPC2146 的USB 开发.19. 非常详细步进电机控制原理图.20. C++ GUI Programming with Qt 4一书中的第一章源码.21. C++ GUI Programming with Qt 4一书中的chap02源码.22. C++ GUI Programming with Qt 4一书中的chap03源码.23. C++ GUI Programming with Qt 4一书中的chap05源码.24. C++ GUI Programming with Qt 4一书中的chap06源码.25. C++ GUI Programming with Qt 4一书中的chap07源码.26. C++ GUI Programming with Qt 4一书中的chap8源码.27. C++ GUI Programming with Qt 4一书中的chap9源码.28. 具有無線網路功能下載至嵌入式開發平台上用的.o黨 driver.29. ADI DSP ADSP-BF561原装开发板的PCB图,非常难得! POWERPCB 5.0可以打开..30. ADI TS201 原装系统板PCB图, 此PCB图是用POWERPCB 5.0画的, 直接导入既可打开, 目前做相控阵雷达,3G 基站,wimax基站等均采用ADSP-TS201..31. ADI DSP BF561 系统板原理图,只有PDF格式的,.32. 利用89C52开发的.33. PCtoLCD2002完美版 取字模软件.34. lm317 计算工具.35. 这是一个非常不错的12864液晶串口程序.36. 嵌入式系统开发原理、工具及过程 值得推荐.37. minigui－－面向实时嵌入式系统的图形用户界面。此文档介绍了miniguide体系结构。.38. 该源码与书本配套.39. 《EVC高级编程及其应用开发》一书的全部源代码.40. 将MATLAB窗口画在VC的GUI上 轻松实现用MATLAB和VC画图.
标签： 网络通信协议
上传时间： 2013-06-12
上传用户：eeworm
VIP专区-嵌入式/单片机编程源码精选合集系列（150）资源包含以下内容：1. ＴＣＲＴ５０００光电传感器.2. 关于PLC控制的资料,内容全面,供参考用..3. 这是设计好并调试通过了的智能负载电路原理图和PCB板图.4. I2C 总线8 位远程I/O 扩展口芯片PCF8574 的原理与应用.5. 基于ADI 公司的blackfin芯片的通用中断框架程序.6. 基于ADI blackfin 的DMA 描述符方式的程序。便于你理解这种独特的dma搬送方式.7. 基于ADI blackfin的异常处理程序.8. 基于ADI BLACKFIN的jbig压缩和解压缩程序.9. max531的驱动程序,采用SPI接收方式.经验证,完全正确..10. 关于自制C8051单片机编程器的文档.11. 国内某测温系统信号处理处理板的代码.12. PIC系列单片机典型应用程序集: 17c42.13. PIC系列单片机典型应用程序集: 24lc.14. PIC系列单片机典型应用程序集: 93c46.15. PIC系列单片机典型应用程序集: 93c.16. PIC系列单片机典型应用程序集: b16tobcd.17. PIC系列单片机典型应用程序集: bcd.18. PIC系列单片机典型应用程序集: BCD2BIN.19. PicoBlaze 处理器 SPI Flash 编程器的详细资料.20. 简易灰度调制.21. LCD ST7787 QVGA 屏 的 驱 动.22. PICC学习.23. 这些都是常用的通信设备的电路原理图.24. 调试好的LCDTV方案.25. 串口中断＿niosII.c SOPC UART!.26. NIOSII I2C源程序.27. C语言规范,在写程序可以避免一些不必要的错误.28. 10分钟学会PLD,仿真.29. ARM平台下的数字音频AGC处理源代码 采用EP9302,对数字音频进行AGC处理.30. VESA and Industry Standard and Guidelines for Computer Display Monitor Timing Version 1.0.31. 基于89s52单片机.32. 基于51系列单片机的开机计数实验.33. 基于wimax中ofdm在vxworks的仿真代码.34. C8051F系列单片机测温程序.35. 5615十位DA转换芯片C的原程序.36. 缝纫机主机板测试程序； 使用嵌入式系统。.37. ATmega48-88-168_中文说明书.38. nios键盘数码管驱动芯片HD7279驱动程序.39. C+++GUI Programming with Qt4 的源码.40. Philip ISP1181芯片驱动.
上传时间： 2013-04-15
上传用户：eeworm
