選擇衰落 的英文怎麼說

中文拼音 [xuǎnzháishuāilà]
選擇衰落 英文
selective fading
  • 選 : Ⅰ動詞1. （挑選） select; choose; pick 2. （選舉） elect Ⅱ名詞（挑選出來編在一起的作品） selections; anthology
  • 擇 : 擇動詞（挑選） select; pick; choose
  • 衰 : 衰動詞（衰弱） decline; wane
  • 落 : 落名詞[方言] （北方對蓮花落的俗稱） a kind of folk song
  • 選擇 : select; choose; opt; election; choice; culling; alternative
  • 衰落 : decline; be on the wane; go downhill; fading; decay; decaying; lapse; erode
  1. And then facing the problem of the channel estimation of the adaptive modulation system, we conclude out the channel estimation algorithms on maximum likelihood ( ml ) estimation and maximum a posteriori ( map ) estimation under the condition of flat fading channel and selective fading channel in detail. to meet flat fading channel, we simulate the relationship of the ratio between the error covariance in map estimation and ml estimation and pilot symbol message length. the conclusion can be drawn from these results

    接著，對自適應調制系統中的通道估計問題難點，詳細推導了平衰落通道條件下和選擇性衰落通道條件下最大似然（ ml ）估計和最大后驗概率（ map ）估計演算法，針對平衰落通道，我們模擬了map估計和ml估計的方差與導頻符號長度的關系，模擬結果表明，錯誤方差受多譜勒頻率的變化影響最大，並且對實際的自適應調制系統，導頻符號長度的取值超過20個符號長度時， map通道估計明顯優于ml通道估計。
  2. In this thesis, for the merits of high frequency spectrum utility factor and high - speed data communication, the ofdm is introduced into the underwater acoustic communication. combined with fec to combat the frequency - selective fades and isi in the underwater acoustic channel, high speed data transmission is realized by employing ofdm technology

    本研究嘗試將ofdm技術引入水聲通信領域，利用該技術頻譜利用率高，多載波并行傳送的特點，結合通道編碼，以克服水聲通道多徑干擾引起的頻率選擇性衰落和碼間干擾，獲得高速率數據傳輸。
  3. Two simulation algorithms of realization channel characteristic are analyzed emphatically : shaping of slow fading with correlation and generation of frequency - selected multipath fading

    重點分析了實現通道特性模擬的兩種演算法：慢衰落的相關性整形和頻率選擇性多徑衰落。
  4. And the most advantage of ofdm is that it can convert high - rate data stream into the low - rate and reduce data bandwidth so that multi - path - fading can be transformed into flat fading in wireless circumstance

    這種調制技術的最大的好處就是將高速的數據流，變換成并行的低速數據流，減小了數據帶寬，從而可將無線環境中的多徑衰落（頻率選擇性率落）轉換成平坦衰落。
  5. The basic idea of this method is to produce particles from the posterior densities, and these weighted samples provide approximations to the densities. in this dissertation, sequential monte carlo method and its applications in communication are investigated. firstly, its basic idea, method and improved method are introduced, then induce the bound of particles, which determines the performance of the system, and the more particles are chosen, the higher computation is done, finally, a new detector based on new importance function is proposed, which deals with the joint channel estimation and detection in flat fading channels

    首先介紹了它的基本思想、基本方法、及當前研究現狀；在此基礎上推導出樣本數選擇的界，樣本數的選擇決定了系統的性能，但是若選的太多，計算復雜度也會隨之增大，因而給出這個界是十分有意義的；最後提出了一種基於新的重要函數的檢測器用來解決平坦衰落通道下的聯合通道估計和檢測問題，並通過模擬證明了我們提出的新檢測器的有效性。
  6. In this thesis, first, we present the theory of sess system, the generation of the sess spreading code and its characteristics and the acquisition theory of conventional spread spectrum communication system. an efficient acquisition scheme based on periodically transmitting the synchronization head, which is composed of binary chaotic codes, using the matched filter and automatic decision threshold - level control based on a so - called constant false alarm criterion for sess system is present. the acquisition model of sess system is built and simulated in the awgn channel, the raleigh fading channel and imulti - address interfere condition

    本文首先概述了自編碼擴頻通信的原理、自編碼擴頻序列的產生方法及其特性和擴頻通信系統編碼同步的理論，然後針對自編碼擴頻通信系統提出了擴頻序列捕獲方案:周期性地加入混沌序列同步碼，並採用恆虛警率匹配濾波器捕獲法;在加性白高斯噪聲通道、瑞利衰落通道和多址干擾情況下進行了模擬，分析了各種捕獲性能:在選擇性能最優的混沌序列、適當的序列長度、虛警概率及門限值的情況下，可以獲得較短的捕獲時間和較大的捕獲概率。
  7. As the step of the color tv ( the second generation ) to the digital tv ( the third generation ) is larger and larger, the research of digital television terrestrial broadcasting ( dttb ) become more and more important in china, we are concentrating on the standard of dttb which is suit for our country after describing and analyzing the technical stipulation and speciality of dttb, this paper compares atsc 8 - vsb with dvb - t cofdm and isdb - t bst - ofdmo the emphasis of this article lies in the technical solution about transferring system, channel coding is important component of dttb, which can resist from the bad circumstances o because of lots of varieties and different performance, channel coding become one of the emphasis of the research work this paper analyzes and researches the theory and performance of the different channel coding particularly, points out an effective theoretic analysis method and computer demo of performance comparison a theoretical method for estimating the performance of concatenated codes is proposed in this paperc this is achieved by combining the performance of single level coding rayleigh fading channel and the character of channel modulation it may be useful to research and development of the future digital television terrestrial broadcasting standard of our country

    通道糾錯編碼是數字電視地面廣播傳輸系統的重要組成部分，是抵禦地面惡劣環境的有效手段。由於通道編碼的種類繁多，性能各異，因此是目前研究工作的重點之一。本文詳細分析和研究了幾種通道糾錯編碼的原理和性能，並針對外碼內碼級聯糾錯結合地面通道瑞利衰落提出了一種有效的理論分析方法和性能的計算機比較演示方案，總結了不同級聯方案的性能特點，對於我國目前的數字電視地面廣播標準的研究和通道級聯糾錯方案的確立及其參數選擇具有一定的參考價值。
  8. Under rayleigh fading channel, we also simulated and compared ber in siso 、 simo and mimo systems. secondly, based on careful study the ber and the channel capacity under white noise channel under mpsk modulation when the channel is rayleigh fading, we duduced the expressions of stbc ’ s ber and channel capacity under rice and nakagami fading. and also analysed the performances through numerical simulation using matlab to testify the exactitude of the dudeced expressions. finally, there exists an error floor of stbc through studying on its performance on time - selectiv fading channel. we analysed the reason and proposed two new decode combination scheme to eliminated the error floor and the performance of stbc on time - selective fading channel is improved. and also compared the two scheme ’ s complication and snr gain

    這些結果大部分是閉式結果，能比較準確地衡量空時塊碼的性能，並對不同衰落的性能做了相互比較，其結果對空時塊碼的實際應用具有一定的指導意義。實際的通道是時變的，分析了空時塊碼在時間選擇性衰落通道中產生誤差地板效應的主要原因是存在碼間干擾（ isi ） ，在此基礎上提出了兩種能消除誤差地板效應的譯碼合併方案，並對這兩種方案的復雜度和信噪比增益進行了比較。
  9. The conclusion is identified by computer simulation. the paper studies a noncoherent demodulation based on differential encoding in mc - cdma system and makes computer simulation of ber performance compared with that of coherent demodulation based on perfect channel estimation

    研究分析了一種使用差分編碼的非相干接收mc - cdma系統，對頻率選擇性瑞利衰落通道條件下的誤碼率性能進行了計算機模擬，並且和基於理想通道估計的相干解調方案進行了比較。
  10. The paper proposes a feedback pre - equalization ( f - pe ) method based on channel estimation in a frequency - selective rayleigh fading channel

    在頻率選擇性瑞利衰落通道條件下，提出一種基於通道估計的反饋?預補償均衡檢測演算法。
  11. Then, we discuss the model of a 256 sub - carriers mc - cdma system and analyze ber performance in a frequency - selective rayleigh fading channel

    討論了一個256載波的mc - cdma系統的數學模型，分析了在頻率選擇性瑞利衰落通道中的誤碼率性能。
  12. A new approach to equalization of linear single - input single - output time - selective fading channel

    時間選擇性衰落通道迫零均衡新方法
  13. The following algorithms have been proposed and tested in the thesis : 1 frequency selective fading : combine the isomorphism between the input space and the output space and propose a new approach to blind equalization of the channel. compared with conventional methods, the new approach offers lower computational complexity, better performance, and more robust against the over - determination of the system order ; 2 time selective fading : a new approach to the equalization of time selective channel based on the zero - forced equalizer is proposed which is more simple in its structure of algorithm ; 3 time - varying channel : using the instantaneous mean value changes of the output signal to extract the information of channel variations and model it using ar model, kalman filter is then employed to track channel variations, it bears faster ability in tracking the variation of tv channels ; based on the isomorphism between the inputs and the outputs and some of the approaches using in mimo system, a new algorithm of equalization of simo time - varying channel is proposed, which also share the merits of being robust against the over - determination of the system order ; model the time - varying channel using the multi - resolution decomposition wavelets, and then a blind identification method based " on the model is proposed ; at last, a new model for equalization and identification of mimo system is proposed

    主要工作在以下幾個方面： 1 、針對頻率選擇性衰落通道：結合輸入輸出空間同構關系提出一種新的頻率選擇性通道均衡方法，與傳統方法相比，該方法計算量更小，收斂速度更快，性能更優，且對系統階次的過確定表現穩健，具有實際均衡應用價值； 2 、針對時間選擇性衰落通道：提出一種基於迫零均衡的時間選擇性通道均衡方法，演算法結構簡單； 3 、針對時變色散通道：利用瞬態均值曲線提取通道時變信息，對之ar建模，利用卡爾曼濾波器跟蹤時變通道抽頭變化，可以快速跟蹤通道變化；基於輸入輸出空間之間的同構關系以及多輸入多輸出系統的處理方法，提出了新的單輸入多輸出色散時變通道均衡與識別演算法，同樣具有對通道階次過確定保持穩健的優點；結合小波多解析度分析提出一種基於小波模型的通道盲識別演算法；研究時變的多輸入多輸出系統的盲均衡與盲反卷積問題，給出一種時變系統處理模型。
  14. 3 a novel recursive least - square ( rls ) blind space - time receiver algorithm based on the constrained condition, which can completely avoid the matrix inversion introduced into by constraints ( comparing with the normal rls ), is proposed for multi - path slow fading cdma channels. the computational complexity of this method is not only lower than that of the normal rls, but also lower than that of both lms and ls blind space - time receiver methods that are realized based on the rosen ' s gradient projection. and the speed of convergence of the presented rls blind space - time receiver algorithm is better than that of both lms and ls blind space - time receiver methods

    3 、針對多徑慢衰落通道下ds - cdma盲空時接收機中線性約束二次規劃問題提出一種新的遞歸最小二乘演算法，該演算法完全避免因約束而引進的矩陣求逆運算（相對于常規的遞歸最小二乘演算法） ，不但運算量比常規的要低，而且比基於rosen梯度投影實現的最小均方（ lms ）與最小二乘盲空時接收機演算法還低，且收斂速度比基於rosen梯度投影實現的最小均方（ lms ）與最小二乘盲空時多用戶檢測都好，將提出的新的遞歸最小二乘演算法與提出的數據選擇方案結合起來可以進一步降低其運算量，具有很大的實用價值，最後通過模擬實驗進一步分析了其性能。
  15. Combined with the data - selected schemes proposed, the computational complexity of this method can be lowered. the performance of the presented rls method is analyzed by simulations, and it is shown that this method is interesting for application. 4 time - selective channel signal model based on multipath - doppler diversity representation is given in multi - path fast fading channel, and rls space - time receiver algorithm based on time - varied constraint condition is presented and the computational complexity of this method is analyzed

    4 、針對多徑快衰落通道下的ds - cdma系統，給出了基於多徑-多譜勒觀點描述的1百安電弓卜科東兔j憶學協士學位論文時間選擇性通道的信號模型，提出了基於變約束條件下的遞歸最小二乘空時接收機演算法並分析演算法的運算量，最後通過模擬分析了所提出的方法的性能。
  16. But when the bit rate is above 1 mbps, the signal suffers frequency select fading, which causes the serious intersymbol interference ( isi ). increasing the system power can ’ t reduce the ber

    但是當碼速率提高到1mbps以上時，信號受到頻率選擇性衰落，碼間干擾嚴重，增大系統功率也不能降低系統誤碼率。
  17. The problems of carrier frequency offset estimation under the condition of the agwn channel, frequency flat - fading channel and frequency selective - fading channel are studied in detail respectively

    本文仔細研究了在高斯白噪聲通道下、頻率平坦衰落通道下和頻率選擇性衰落通道下高精度估計信號載頻偏差的問題，並對相應演算法提出了一些改進辦法。
  18. A time - varying disperse channel is a channel that contain both frequency selective fading and time selective fading

    時變色散通道則是同時存在頻率和時間選擇性衰落的通道。
  19. Finally, the application of mud in the frequency - flat slowly fading multi - path channel is introduced, and to enhance the system efficiency the joint use of the rake receiver and mud is applied in the frequency - selective slowly fading multi - path channel

    最後，在討論了平坦慢衰落通道的基礎上，將rake分集技術和多用戶檢測技術相結合應用於多徑的頻率選擇性慢衰落通道，以達到改良系統的性能的目的。
  20. It is based on the mean square error ( mse ) principle and we prove the validity of the method by computer simulations. to make a thorough understanding of mimo adaptive equalization system, in this thesis the author : 1 ) ananlyze the characteristics of mimo wideband channels and the modeling and simulation of 3gpp scm ; 2 ) research the capability of mimo linear adaptive equalization and mimo non - linear adaptive equalization by computer simulations ; 3 ) present a new method for selecting the order of adfe model 4 ) implement the adfe on adsp - 21160 for static image transmission, and already achieve satisfactory experimental result, which make a foundation for mimo adaptive equalization to be appllied in the real communication systems

    為對mimo自適應均衡系統性能和設計做更深入的理解和研究，本文主要: 1 ）研究了寬帶選擇衰落通道特性及3gppscm通道建模模擬; 2 ） mimo線性自適應均衡器和mimo非線性自適應均衡器系統的性能分析和模擬實現; 3 ） mimo系統下的判決反饋均衡器的階數選擇模擬試驗分析; 4 ）把mimo自適應判決反饋均衡運用到了硬體模擬平臺上，採用了基於adsp - 21160的硬體dsp開發板，對靜止圖片的傳輸進行了試驗、分析和比較，得到了較滿意的實驗結果，使mimo自適應均衡在實際通信系統上的應用及實現奠定了現實基礎。
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