衰落率 的英文怎麼說

中文拼音 [shuāilàlǜ]
衰落率 英文
fading rate
  • 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
  • 率 : 率名詞（比值） rate; ratio; proportion
  • 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. The housing market ' s downswing may not yet be over ; and its weakness could prompt consumers to increase their ultra - low saving rates, cutting into demand

    房屋市場的衰落趨勢或許尚未結束，而且其疲軟狀態會促使消費者提高原本處在極低水平的儲蓄率，這會降低需求。
  3. Therefore, during system design, cascade coding combining reed - solomon codes and convolutional codes is utilized ; in addition, time - direction and frequency - direction interleaves are added to alleviate channel fading

    因此在進行系統設計時，採用了rs碼與卷積碼的級聯編碼方案，並同時加入時間交織和頻率交織來對抗通道衰落。
  4. As a combination of ofdm with space - time coding technique, mimo - ofdm becomes more and more important in the future wireless communication systems, the mimo - ofdm system can not only effectively enhance the transmission rate and capacity of the wireless communication system but also greatly mitigate the effections of mufti - path fading and interfere

    Mimo - ofdm技術將ofdm與空時編碼技術有機的結合在一起，能夠大幅度的提高無線通信系統的通道容量和傳輸效率，並能有效的抵抗多徑衰落、抑制干擾和噪聲。
  5. Based on fractional sampling method, a new super - exponential iteration decision feedback blind equalization algorithm for severely nonlinear phase distortion channels was proposed

    因此針對嚴重頻率衰落和非線性相位失真通道，提出了一種分數采樣的混合盲均衡演算法，並獲得了較快的收斂速度和較小的剩餘均方誤差。
  6. Shortwave channel is time varying transmission channel. it has dispersion in frequency and time domains. this characteristics hinds the data transmi - ssion at high speed and the correction of received data. in this dissertation i have analyzed the statistic characteristic of shortwa - ve channel, established the model of shortwave channel and simulated the rayl eigh fading distribution. the technology of spreading spetrum has been proved that it has the capability for anti - multipath and discerning multipath

    在短波通信中，由於通道的時間色散和頻率色散，引起多徑展寬和多徑衰落，前者限制了數據的傳輸速率，後者造成短波數據通信中出現突發錯誤，為了解決多徑效應對短波通信的影響，本文所做工作如下：首先詳細分析了短波通道的統計特性，建立其數學模型；其次分析了擴頻通信的特點，從理論上證明擴頻技術不僅具有抗多徑干擾能力，而且具有分離多徑的能力；介紹了傳統的rake分集合併技術的特點。
  7. 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。
  8. Turbo codes represent the new code structures, which consist of pccc ( parallel serially convolutional code ) and sccc ( serially concatenated convolutional code ). in this paper, the background of turbo codes are firstly introduced, which includes the base principle of error correction code 、 block code and convolutional code ; the principle of turbo code and the iterative decoding is secondly expanded ; the key decoding algorithm : a revised map algorithm and iterative decoding theory are detailed ; then, a new turbo code structure : hccc ( hybrid concatenated convolutional code ) is presented, and the capacity of this code method is analyzed, the average capacity upper bound is derived ; at last, this code is simulated on awgn ( additive white gaussian noise ) channel and rayleigh fading channel

    本文首先介紹了turbo碼的背景知識，包括差錯控制的基本原理、分組碼和卷積碼；然後闡述了turbo碼的基本原理，包括turbo編譯碼器結構及迭代譯碼原理；較為詳細地描述了關鍵的譯碼演算法： ?種改進的最大后驗概率（ map ）譯碼演算法及迭代譯碼演算法；提出了一種新的turbo碼結構：混合turbo碼（混合級聯卷積碼） ；並用編碼性能聯合界分析方法對混合turbo碼進行了性能分析，得出了其平均性能上界；並在高斯白噪聲通道和瑞利衰落通道上分別作了一些應用研究及計算機模擬實驗。
  9. 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。
  10. 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。
  11. But with its own inefficient economy foundering, and with the gcc countries jointly wielding hundreds of billions of dollars in investment capital, it is the arabs who now carry greater clout

    但是，伊朗由於低效率，經濟日益衰落，而伊國內的幾千億投資資本也都攥在海灣合作委員會成員國的手中，現在看來還是阿拉伯國家的影響力更勝一籌。
  12. Lt is well anown that the multi ? ath effeet results in signal fading and intersymbol interference ( isd, wnich causes great difficulhes in pewces of transndssion in underwater acoushc cotnmnication. in this papef we used frequency diversity method to overcome the problem of signal fading, and used the frequency - hopping method to ebonate the isi caused by multi - path

    水聲通道多途特性引起的信號衰落和碼間干擾是影響水下通信質量的主要因素，採用頻率分集技術可以處理幅度衰落，而跳頻技術則可以簡單、有效地抗多途引起的碼間干擾。
  13. This thesis analyzed the error performance of mfsk and mpsk modulator in hf with optimal receiver, studied the shortcoming and strongpoint of several typical short - wave data transmission systems and their performance over fading and intersymbol interference channels. the theory and key technical of adaptive modem is discussed. in the last, an efficient modulation scheme - block coded modulation is introduced into hf radio systems to improve the efficiency of hf data transmission, this paper also proposes a hf data transmission system scheme composed of a block coded modulator and a decision feedback type adaptive equalizer

    本文在對短波數傳兩種常見調制方式fsk及psk最佳解調性能分析的基礎上，討論了幾種採用典型調制技術的短波數傳系統（如時頻調制、多進制頻移鍵控慢跳頻、 chess系統）原理、優缺點以及抗衰落和抗符號間干擾的性能；分析了自適應串列數傳系統抗短波通道衰落和多徑干擾的原理、關鍵技術；在本文的最後引入一種有望解決短波數傳系統低效率狀況的調制方式bcm -分組編碼調制，給出了一個採用bcm技術與自適應均衡技術相結合的短波數傳系統方案，並通過計算機模擬進行了初部驗證。
  14. 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。
  15. It consists of a powr compensation algorithm based on reverse channel prediction and closed - loop power control algorithm. computer simulation showed that the scheme could compensate the fast channel fading quite well

    它由基於反向通道預測的功率補償演算法和常規閉環功率控制組合而成。計算機模擬結果表明，所提出的組合功率控制方案能夠很好地補償通道的快速衰落。
  16. Abstract : by comparing the channel capacities hetwem orthogonal space - time block coding and multi - antenna array system over rayleigh fading channel, some capacity loss for orthogonal space - time block coding is obtained, which is a function of the code rate, the rank of channel matrix and the number of transmitter and receive antennas, although the system of orthogonal space - time block codes is simple and easy to implemented. if is also shown that there is no capacity loss only if both the code rate and the channel matrix rank are all one

    文摘:在研究瑞利衰落條件下正交空時分組編碼通道容量的基礎上，將其與多發送多接收天線系統的通道容量進行了比較.比較結果表明，正交空時分組碼雖編碼簡單，易於實現，但在通道容量方面存在較大的損失，損失的程度與編碼碼率、通道矩陣的秩及收發天線數等因素有關.進一步研究表明只有當編碼碼率和通道矩陣的秩都為1時，才沒有通道容量的損失
  17. 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。
  18. 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。
  19. This model has the ability of analyzing the effects of some key system parameters, such as the signal correlation coefficient, speed of the mobile, and the update rate of combining weights, on the system performance

    研究了信號相關系數、移動臺運動速度、通道衰落率，以及合併權值更新速度對合併性能的影響。
  20. The measurement further indicates that the fading rate exceeds the median value by a factor of about 7 at 460mc and a factor of about 3. 5 at 4110mc

    測量結果進一步表明，衰落率在460兆赫時超過中值約6倍，在4110兆赫時超過中值約2 . 5倍
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