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.”
標簽： Time-Varying Channels
上傳時間： 2020-06-01
上傳用戶：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.
標簽： TM Bluetooth Zigbee Wi-Fi wimax and
上傳時間： 2020-06-01
上傳用戶：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.
標簽： Multi-hop Networks wimax WiFi Mesh LTE and
上傳時間： 2020-06-01
上傳用戶：shancjb
所設計的多頻段小型化天線結構新穎，性能指標優越，與當前國內外研究的大多數同類天線相比保持較小體積，在多頻、寬頻工作頻段上也保持較強的競爭力。其中所設iMonopole，780MHz-1010MHz和1630MHz3900MHz，在高頻頻段上的提升相當明顯，與大多數同類天線相比提升超過100%，除了覆蓋GSM，UMTS，LTE的頻段外，還覆蓋wimax的頻段，為未來5G通信的多頻段融合發展提供有力支撐；所設計多頻段小型化PIFA天線，工作頻段為680MHz980MHz和1665MHz-2755MHz，覆蓋GSM，UMTS，LTE所需的所有頻段，同時該天線的小型化指標憂異，其輻射貼片部分的尺寸僅為33mm x mm0.8mm，在當前國內外同類天線中具有相當強的競爭力。這兩款天線結構簡單，加工成本低，十分適用于5G移動通信移動終端中。最后，設計一款超寬帶微帶天線。所設計的超寬帶微帶天線利用新型倒置E型槽，獲得了超寬帶性能，工作頻段覆蓋27.6GHz-33.2GHz.采用新的債電方式一半圓漸進饋電，不僅可以改善天線的輻射特性，還能降低阻抗匹配的難度，進而一定程度上簡化了天線的設計難度。在天線輻射貼片開有圓角矩形槽，大大的改善了天線的阻抗特性，進一步優化了天線的輻射特性，保證了天線在整個煩段內輻射方向圖的穩定性。天線加工簡單、成本低，非常適用于5G移動通信的大規模組網。
上傳時間： 2022-06-20
上傳用戶：
5G，第五代移動通信技術，也是4G之后的延伸，目前正在研究中。目前還沒有任何電信公司或標準訂定組織（像3GPP，wimax論壇及ITU-R）的公開規格或官方文件有提到5G。按照業內初步估計，包括5G在內的未來無線移動網絡業務能力的提升將在3個維度上同時進行：1）通過引入新的無線傳輸技術將資源利用率在4G的基礎上提高10倍以上；2）通過引入新的體系結構（如超密集小區結構等）和更加深度的智能化能力將整個系統的吞吐率提高25倍左右；3）進一步挖掘新的頻率資源（如高頻段、毫米波與可見光等），使未來無線移動通信的頻率資源擴展4倍左右.5G有以下特點：1）5G研究在推進技術變革的同時將更加注重用戶體驗，網絡平均吞吐速率、傳輸時延以及對虛擬現實、3D、交互式游戲等新興移動業務的支撐能力等將成為衡量5G系統性能的關鍵指標.2）與傳統的移動通信系統理念不同，5G系統研究將不僅僅把點到點的物理層傳輸與信道編譯碼等經典技術作為核心目標，而是從更為廣泛的多點、多用戶、多天線、多小區協作組網作為突破的重點，力求在體系構架上尋求系統性能的大幅度提高.3）室內移動通信業務已占據應用的主導地位，5G室內無線覆蓋性能及業務支撐能力將作為系統優先設計目標，從而改變傳統移動通信系統“以大范圍覆蓋為主、兼顧室內"的設計理念.4）高頻段頻譜資源將更多地應用于5G移動通信系統，但由于受到高頻段無線電波穿透能力的限制，無線與有線的融合、光載無線組網等技術將被更為普遍地應用.5）可“軟”配置的5G無線網絡將成為未來的重要研究方向，運營商可根據業務流量的動態變化實時調整網絡資源，有效地降低網絡運營的成本和能源的消耗.
上傳時間： 2022-06-21
上傳用戶：
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
上傳時間： 2022-07-08
上傳用戶：
VIP專區-嵌入式/單片機編程源碼精選合集系列（109）資源包含以下內容：1. 包括匯編和c++編寫的萬年歷.2. FIFO（先進先出隊列）通常用于數據的緩存和用于容納異步信號的頻率或相位的差異。本FIFO的實現是利用 雙口RAM 和讀寫地址產生模塊來實現的.FIFO的接口信號包括異步的寫時鐘（wr_clk）和讀.3. Analog signals are represented by 64 bit buses. They are converted to real and from real representa.4. 該文件為lpc2106 ARM7在THREDX操作系統下的啟動代碼.5. 該代碼為時鐘芯片PCF8563的控制程序.6. 此代碼位PIC單片機的PID控溫程序.7. threadx技術手冊.8. 一個關于fat32系統文件的說明,對了解fat32文件系統系統結構很有用.9. 典型的開發模型有：①瀑布模型(waterfall model)；②漸增模型/演化/迭代(incremental model)；③原型模型(prototype model)；④螺旋模型(spiral m.10. zigbee協議中.11. 三菱FX系列PLC與PC機通過編程口通訊的地址轉換軟件,非常的使用!.12. 文章講述了類似于PDOP值的描述整周模糊度精度的指標因子。對于整周模糊度的判斷具有重要意義。.13. 講述了如何對主引導扇區進行備份和恢復.14. LED驅動電路實例。配具體的電路圖供大家參考使用.15. Pcb初級教程.16. 嵌入式內存數據庫系統eXtremeDB用戶指南.17. 對引導區的學駐病毒進行了剖析.18. LPC2146 的USB 開發.19. 非常詳細步進電機控制原理圖.20. C++ GUI Programming with Qt 4一書中的第一章源碼.21. C++ GUI Programming with Qt 4一書中的chap02源碼.22. C++ GUI Programming with Qt 4一書中的chap03源碼.23. C++ GUI Programming with Qt 4一書中的chap05源碼.24. C++ GUI Programming with Qt 4一書中的chap06源碼.25. C++ GUI Programming with Qt 4一書中的chap07源碼.26. C++ GUI Programming with Qt 4一書中的chap8源碼.27. C++ GUI Programming with Qt 4一書中的chap9源碼.28. 具有無線網路功能下載至嵌入式開發平臺上用的.o黨 driver.29. ADI DSP ADSP-BF561原裝開發板的PCB圖,非常難得! POWERPCB 5.0可以打開..30. ADI TS201 原裝系統板PCB圖, 此PCB圖是用POWERPCB 5.0畫的, 直接導入既可打開, 目前做相控陣雷達,3G 基站,wimax基站等均采用ADSP-TS201..31. ADI DSP BF561 系統板原理圖,只有PDF格式的,.32. 利用89C52開發的.33. PCtoLCD2002完美版 取字模軟件.34. lm317 計算工具.35. 這是一個非常不錯的12864液晶串口程序.36. 嵌入式系統開發原理、工具及過程 值得推薦.37. minigui－－面向實時嵌入式系統的圖形用戶界面。此文檔介紹了miniguide體系結構。.38. 該源碼與書本配套.39. 《EVC高級編程及其應用開發》一書的全部源代碼.40. 將MATLAB窗口畫在VC的GUI上 輕松實現用MATLAB和VC畫圖.
標簽： 網絡通信協議
上傳時間： 2013-06-12
上傳用戶：eeworm
VIP專區-嵌入式/單片機編程源碼精選合集系列（150）資源包含以下內容：1. ＴＣＲＴ５０００光電傳感器.2. 關于PLC控制的資料,內容全面,供參考用..3. 這是設計好并調試通過了的智能負載電路原理圖和PCB板圖.4. I2C 總線8 位遠程I/O 擴展口芯片PCF8574 的原理與應用.5. 基于ADI 公司的blackfin芯片的通用中斷框架程序.6. 基于ADI blackfin 的DMA 描述符方式的程序。便于你理解這種獨特的dma搬送方式.7. 基于ADI blackfin的異常處理程序.8. 基于ADI BLACKFIN的jbig壓縮和解壓縮程序.9. max531的驅動程序,采用SPI接收方式.經驗證,完全正確..10. 關于自制C8051單片機編程器的文檔.11. 國內某測溫系統信號處理處理板的代碼.12. PIC系列單片機典型應用程序集: 17c42.13. PIC系列單片機典型應用程序集: 24lc.14. PIC系列單片機典型應用程序集: 93c46.15. PIC系列單片機典型應用程序集: 93c.16. PIC系列單片機典型應用程序集: b16tobcd.17. PIC系列單片機典型應用程序集: bcd.18. PIC系列單片機典型應用程序集: BCD2BIN.19. PicoBlaze 處理器 SPI Flash 編程器的詳細資料.20. 簡易灰度調制.21. LCD ST7787 QVGA 屏 的 驅 動.22. PICC學習.23. 這些都是常用的通信設備的電路原理圖.24. 調試好的LCDTV方案.25. 串口中斷＿niosII.c SOPC UART!.26. NIOSII I2C源程序.27. C語言規范,在寫程序可以避免一些不必要的錯誤.28. 10分鐘學會PLD,仿真.29. ARM平臺下的數字音頻AGC處理源代碼 采用EP9302,對數字音頻進行AGC處理.30. VESA and Industry Standard and Guidelines for Computer Display Monitor Timing Version 1.0.31. 基于89s52單片機.32. 基于51系列單片機的開機計數實驗.33. 基于wimax中ofdm在vxworks的仿真代碼.34. C8051F系列單片機測溫程序.35. 5615十位DA轉換芯片C的原程序.36. 縫紉機主機板測試程序； 使用嵌入式系統。.37. ATmega48-88-168_中文說明書.38. nios鍵盤數碼管驅動芯片HD7279驅動程序.39. C+++GUI Programming with Qt4 的源碼.40. Philip ISP1181芯片驅動.
上傳時間： 2013-04-15
上傳用戶：eeworm
