Software Radio (SR) is one of the most important emerging technologies for the future of wireless communication services. By moving radio functionality into software, it promises to give flexible radio systems that are multi-service, multi- standard, multi-band, reconfigurable and reprogrammable by software. Today’s radios are matched to a particular class of signals that are well defined bytheircarrierfrequencies,modulationformatsandbandwidths.Aradiotransmitter today can only up convert signals with well-defined bandwidths over defined center frequencies, while, on the other side of the communication chain, a radio receiver can only down convert well-defined signal bandwidths, transmitted over specified carrier frequencies.
上傳時(shí)間： 2020-06-01
上傳用戶：shancjb
The radio spectrum is one of the most precious resources which must be managed to ensure efficient access for the wireless communication services which use it. The allocation and management of spectrum are administered by the regulatory authorities. Traditionally, spectrum allocation is carried out exclusively of its use in large geographic areas and assigning frequency bands to specific users or service providers is proved to be inefficient. Recently, substantial knowledge about dynamic spectrum access scheme has been accumulated to enable efficient spectrum sharing.
標(biāo)簽： Management Spectrum Access and
上傳時(shí)間： 2020-06-01
上傳用戶：shancjb
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(biāo)簽： Time-Varying Channels
上傳時(shí)間： 2020-06-01
上傳用戶：shancjb
Recent advances in wireless communication technologies have had a transforma- tive impact on society and have directly contributed to several economic and social aspects of daily life. Increasingly, the untethered exchange of information between devices is becoming a prime requirement for further progress, which is placing an ever greater demand on wireless bandwidth. The ultra wideband (UWB) system marks a major milestone in this progress. Since 2002, when the FCC allowed the unlicensed use of low-power, UWB radio signals in the 3.1–10.6GHz frequency band, there has been significant synergistic advance in this technology at the cir- cuits, architectural and communication systems levels. This technology allows for devices to communicate wirelessly, while coexisting with other users by ensuring that its power density is sufficiently low so that it is perceived as noise to other users.
標(biāo)簽： Circuits Wideband Ultra
上傳時(shí)間： 2020-06-01
上傳用戶：shancjb
Resource allocation is an important issue in wireless communication networks. In recent decades, cognitive radio technology and cognitive radio-based networks have obtained more and more attention and have been well studied to improve spectrum utilization and to overcomethe problem of spectrum scarcity in future wireless com- munication systems. Many new challenges on resource allocation appear in cogni- tive radio-based networks. In this book, we focus on effective solutions to resource allocation in several important cognitive radio-based networks, including a cogni- tive radio-basedopportunisticspectrum access network, a cognitiveradio-basedcen- tralized network, a cognitive radio-based cellular network, a cognitive radio-based high-speed vehicle network, and a cognitive radio-based smart grid.
標(biāo)簽： Cognitive Networks Radio
上傳時(shí)間： 2020-06-07
上傳用戶：shancjb
EN 300220-1V2.4.1 Electromagnetic compatibility and Radio spectrum Matters (ERM);Short Range Devices (SRD);Radio equipment to be used in the 25 MHz to 1 000 MHz frequency range with power levels ranging up to 500 mW; Part 1: Technical characteristics and test methods
標(biāo)簽： EMC
上傳時(shí)間： 2021-07-25
上傳用戶：beiyouxia
EIMAC Tube Catalog ( ref data) - Radio and TV Broadcasters (z-lib.org)
標(biāo)簽： eimac
上傳時(shí)間： 2022-01-16
上傳用戶：
近幾年來，OFDM(Orthogonal Frequency Division Multiplexing)技術(shù)引起了人們的廣泛注意，根據(jù)這項(xiàng)新技術(shù)，很多相關(guān)協(xié)議被提出來。其中WiMax(Wireless MetropolitanArea Networks)代表空中接口滿足IEEE 802.16標(biāo)準(zhǔn)的寬帶無線通信系統(tǒng)，IEEE標(biāo)準(zhǔn)在2004年定義了空中接口的物理層(PHY)，即802.16d協(xié)議。該協(xié)議規(guī)定數(shù)據(jù)傳輸采用突發(fā)模式，調(diào)制方式采用OFDM技術(shù)，傳輸速率較高且實(shí)現(xiàn)方便、成本低廉，已經(jīng)成為首先推廣應(yīng)用的商業(yè)化標(biāo)準(zhǔn)。 本文主要對(duì)IEEE802.16d OFDM系統(tǒng)物理層進(jìn)行研究，并在XILINX公司的Virtexpro II芯片上實(shí)現(xiàn)了基帶算法。 首先討論了OFDM基本原理及其關(guān)鍵技術(shù)。根據(jù)IEEE802.16d OFDM系統(tǒng)的物理層發(fā)送端流程搭建了基帶仿真鏈路，利用MATLAB/SIMULINK仿真了OFDM系統(tǒng)在有無循環(huán)前綴(CP)、多徑數(shù)目不同等情況下的性能變化。由于同步算法和信道估計(jì)算法計(jì)算量都很大，為了找到適合采用FPGA實(shí)現(xiàn)的算法，分析了同步誤差和不同信道估計(jì)算法對(duì)接收信號(hào)的影響，并結(jié)合計(jì)算量的大小提出了一種新的聯(lián)合同步算法，以及得出了LS信道估計(jì)算法最適合802.16d系統(tǒng)的結(jié)論。 其次，完成了基帶發(fā)射機(jī)和接收機(jī)的FPGA硬件電路實(shí)現(xiàn)。為了使系統(tǒng)的時(shí)鐘頻率更高，采用了流水線的結(jié)構(gòu)。設(shè)計(jì)中采用編寫Verilog程序和使用IP核相結(jié)合的辦法，實(shí)現(xiàn)了新的聯(lián)合同步算法，并且通過簡化結(jié)構(gòu)，避免了信道估計(jì)算法中的繁瑣除法。利用ISE9. 2i和Modelsim6.Oc軟件平臺(tái)對(duì)程序進(jìn)行設(shè)計(jì)、綜合和仿真，并將仿真結(jié)果和MATLAB軟件計(jì)算結(jié)果相對(duì)比。結(jié)果表明，采用16位數(shù)據(jù)總線可達(dá)到理想的精度。 最后，采用串口通信的方式對(duì)基帶系統(tǒng)進(jìn)行了驗(yàn)證。通過串口通信從功能上表明該系統(tǒng)確實(shí)可行。 關(guān)鍵詞：IEEE802. 16d； OFDM； 同步；信道估計(jì)；基帶系統(tǒng)
上傳時(shí)間： 2013-07-31
上傳用戶：1757122702
軟件無線電（Software Defined Radio）是無線通信系統(tǒng)收發(fā)信機(jī)的發(fā)展方向，它使得通信系統(tǒng)的設(shè)計(jì)者可以將主要精力集中到收發(fā)機(jī)的數(shù)字處理上，而不必過多關(guān)注電路實(shí)現(xiàn)。在進(jìn)行數(shù)字處理時(shí)，常用的方案包括現(xiàn)場可編程門陣列（FPGA）、數(shù)字信號(hào)處理器（DSP）和專用集成電路（ASIC）。FPGA以其相對(duì)較低的功耗和相對(duì)較低廉的成本，成為許多通信系統(tǒng)的首先方案。正是在這樣的前提下，本課題結(jié)合軟件無線電技術(shù)，研究并實(shí)現(xiàn)基于FPGA的數(shù)字收發(fā)信機(jī)。 @@ 本論文主要研究了發(fā)射機(jī)和接收機(jī)的結(jié)構(gòu)和相關(guān)的硬件實(shí)現(xiàn)問題。首先，從理論上對(duì)發(fā)射機(jī)和接收機(jī)結(jié)構(gòu)進(jìn)行研究，找到收發(fā)信機(jī)設(shè)計(jì)中關(guān)鍵問題。其次，在理論上有深刻認(rèn)識(shí)的基礎(chǔ)上，以FPGA為手段，將反饋控制算法、反饋補(bǔ)償算法和前饋補(bǔ)償算法落實(shí)到硬件電路上。同步一直是數(shù)字通信系統(tǒng)中的關(guān)鍵問題，它也是本文的研究重點(diǎn)。本文在研究了已有各種同步方法的基礎(chǔ)上，設(shè)計(jì)了一種新的同步方法和相應(yīng)的接收機(jī)結(jié)構(gòu)，并以硬件電路將其實(shí)現(xiàn)。最后，針對(duì)所設(shè)計(jì)的硬件系統(tǒng)，本文還進(jìn)行了充分的硬件系統(tǒng)測試。硬件測試的各項(xiàng)數(shù)據(jù)結(jié)果表明系統(tǒng)設(shè)計(jì)方案是可行的，基本實(shí)現(xiàn)了數(shù)字中頻收發(fā)機(jī)系統(tǒng)的設(shè)計(jì)要求。 @@ 本文中發(fā)射機(jī)系統(tǒng)是以Altera公司EP2C70F672C6為硬件平臺(tái)，接收機(jī)系統(tǒng)以Altera公司EP2S180F1020C3為硬件平臺(tái)。收發(fā)系統(tǒng)均是在Ouartus Ⅱ 8．0環(huán)境下，通過編寫Verilog HDL代碼和調(diào)用Altera IP core加以實(shí)現(xiàn)。在將設(shè)計(jì)方案落實(shí)到硬件電路實(shí)現(xiàn)之前，各種算法均使用MATLAB進(jìn)行原理仿真，并在MATLAB仿真得到正確結(jié)果的基礎(chǔ)上，使用Quartus Ⅱ 8．0中的功能仿真工具和時(shí)序仿真工具進(jìn)行了前仿真和后仿真。所有仿真結(jié)果無誤后，可下載至硬件平臺(tái)進(jìn)行調(diào)試，通過Quartus Ⅱ 8．0中集成的SignalTap邏輯分析儀，可以實(shí)時(shí)觀察電路中各點(diǎn)信號(hào)的變化情況，并結(jié)合示波器和頻譜儀，得到硬件測試結(jié)果。 @@關(guān)鍵詞：SDR；數(shù)字收發(fā)機(jī)；FPGA；載波同步；符號(hào)同步
標(biāo)簽： FPGA 數(shù)字中頻 收發(fā)信機(jī)
上傳時(shí)間： 2013-04-24
上傳用戶：diaorunze
隨著人們對(duì)于高速無線數(shù)據(jù)業(yè)務(wù)的急切需求以及新的無線通信技術(shù)的發(fā)展，頻譜資源匱乏問題日益嚴(yán)重。無線頻譜的緊缺已經(jīng)成為限制無線通信與服務(wù)應(yīng)用持續(xù)發(fā)展的瓶頸。認(rèn)知無線電技術(shù)(Cognitive Radio)改變了傳統(tǒng)的固定頻譜分配方式，它以頻譜利用的高效性為目標(biāo)，允許非授權(quán)用戶擇機(jī)利用授權(quán)用戶的頻譜空洞傳輸數(shù)據(jù)，以此來解決無線頻譜資源短缺的問題。它是具有自主尋找和使用空閑頻譜資源能力的智能無線電技術(shù)。本文的目標(biāo)是在基于FPGA+DSP的系統(tǒng)硬件平臺(tái)上，以軟件編程的方式實(shí)現(xiàn)認(rèn)知無線電數(shù)據(jù)傳輸?shù)墓δ堋?軟件無線電是實(shí)現(xiàn)認(rèn)知無線電的理想平臺(tái)。本文首先闡述了軟件無線電的基本工作原理及關(guān)鍵技術(shù)途徑，對(duì)多速率信號(hào)處理中的內(nèi)插和抽取、帶通采樣、數(shù)字下變頻、濾波等技術(shù)進(jìn)行了分析與探討，為設(shè)計(jì)多速率調(diào)制解調(diào)系統(tǒng)提供了理論基礎(chǔ)。然后針對(duì)軟件無線電的要求給出了基于FPFA+DSP的系統(tǒng)設(shè)計(jì)硬件框圖，并對(duì)其中的部分硬件(FPGA、AD9857、AD9235)做了簡要的描述并給出其初始化過程。在理解基本概念和原理的基礎(chǔ)上，詳細(xì)論述了在系統(tǒng)硬件設(shè)計(jì)平臺(tái)上實(shí)現(xiàn)的π/4-DQPSK、8PSK、16QAM調(diào)制解調(diào)技術(shù)。本文給出了調(diào)制解調(diào)系統(tǒng)實(shí)現(xiàn)方案中的各個(gè)功能模塊(差分編、解碼，加同步頭、內(nèi)插和成形濾波，下變頻，系統(tǒng)同步等)具體的設(shè)計(jì)方案和通過硬件編程實(shí)現(xiàn)了板級(jí)的仿真和最后的硬件實(shí)現(xiàn)，并對(duì)其中得到的數(shù)據(jù)進(jìn)行分析，進(jìn)一步驗(yàn)證方案的可行性。最后介紹了通信板同頻譜感知板協(xié)同工作原理，依據(jù)頻譜感知板獲取的各個(gè)信道狀況自適應(yīng)的選擇π/4-DQPSK、8PSK、16QAM調(diào)制解調(diào)方式并在FPGA上實(shí)現(xiàn)了其中部分功能。
標(biāo)簽： FPGA 多速率 調(diào)制解調(diào)器
上傳時(shí)間： 2013-05-30
上傳用戶：fywz
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