fading frequency 中文意思是什麼
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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。 -
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。 -
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。 -
Single carrier frequency domain equalization for high data rate transmission systems over frequency selective fading channels
頻率選擇性通道下高速數據傳輸中的單載波頻域均衡技術 -
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。 -
Performance analysis of differential frequency hopping communication system over rayleigh fading channel
接收機在瑞利通道下的性能研究 -
The future wireless mobile communication systems are expected to provide ubiquitous, high - quality, and high - rate mobile multimedia transmission. however, hostile multipath fading radio conditions give rise to serious inter - symbol interference ( isi ) ; even worse, wireless channel are often time varying, which makes the system more vulnerable and more difficult to track the channel state. orthogonal frequency dvision multiplexing ( ofdm ), which is inherently resistant against isi, has invoked a popular research interest in recent years, and has been a promising candidate technology of the physical layer for future weideband high - date - rate wireless communications. notwithstanding, ofdm is much more vulnerable to errors of both time and frequency synchronization and to that of channel estimation, and how to obtain correct timing and channel estimation efficiently is highly critical to ofdm systems. the dissertation will focus on both of the aspects of ofdm systems mentioned above
但是無線環境的多徑特性造成通信系統中嚴重的符號間干擾，同時無線通道的時變性使得通道特性跟蹤復雜。而正交頻分復用技術（ orthogonalfrequencydivisionmultiplexing ， ofdm ）正是一種解決符號間干擾的有效傳輸手段，因此ofdm技術作為未來寬帶高速率無線通信的物理層候選技術在當前引起了一股研究熱潮。但ofdm系統對定時同步誤差和通道估計誤差非常敏感，如何在ofdm系統中準確快速地實現符號同步和通道估計是至關重要的，本論文將重點針對這兩個問題進行討論。 -
The characteristic of the time - variety channel may be represented by rayleigh fading and doppler frequency shift
這種通道的時變特性可用瑞利衰落和多普勒頻移來表徵。 -
When the doppler frequency shift is big and the rayleigh fading is serious, it would affect the despread and demodulation algorithm of the signal badly
當多普勒頻移較大，瑞利衰落嚴重時，將嚴重影響信號的解擴解調。 -
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。 -
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。 -
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。 -
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。 -
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。 -
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。 -
It is very difficult to design a high - quality underwater acoustic data transmission system. in our study, we use frequency diversity and frequency - hopped technology. this method is an effective solution for the isi and signal fading
該方法起到保證mfsk傳輸系統使用頻率中文摘要統使雨頻率分集技術能得以有效的實現；並可用於提高mfsk信號檢測精度，因此在頻率信號檢測中它有廣泛應用意義，它是本文重要創新之處。 -
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。 -
Frequency selective fading
頻率選擇性衰落色散衰落 -
Space - time coded eigenbeamforming for downlink frequency - selective correlated fading
下行頻率選擇性相關衰落通道下的空時特徵波束編碼 -
Because of the different time delay among multi - paths, the received signal undergoes frequency - selective fading
由於多徑干擾之間具有不同的時間延遲，接收信號將承受頻率選擇性衰落。
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