fading channel 中文意思是什麼
fading channel
解釋
衰落通道-
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。 -
Then this paper makes some overview and simulation on the application of three precoding algorithms under the flat fading channel, which are linear preequalization, tomlinson - harashima precoding ( thp ) and lattice reduction - aided ( lll ) vector precoding
本文對三種常見的預編碼演算法在平坦衰落通道下的應用進行了綜述和模擬研究，包括迫零線性預均衡、 thp預編碼和格約簡輔助矢量預編碼等演算法。 -
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。 -
The simplified gaussian approximation can be obtained, which has almost the same in accuracy but much less calculations than improved gaussian approximation method. the single traffic cdma system in nakagami fading channel with rake receiver is investigated extensively. a closed form ber expression is obtained with arbitrary chip waveforms
由於在用戶小時其誤差大，改進高斯法可以提高精度，但需要更多的計算時間，少用戶時直擴系統的工程計演算法能夠獲得與改進高斯法相似的精度，但需要的運算量大為減少。 -
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 -
This thesis has improved the original estimation algorithm gave by mr zhou, and exended to the estimation of the snr of awgn channel and rayleigh fading channel
本文把這種演算法應用到awgn通道和單徑瑞利通道下對信噪比或通道噪聲方差進行估計。 -
When more than 10 6 ( 3, 2 ) parity check codes are used to estimate the snr of awgn channel and rayleigh fading channel, the estimation error is less than 1 %
在bpsk信號通過awgn通道和單徑瑞利通道下使用（ 3 ， 2 ）碼估計，當統計的碼字數達到106以上時，估計誤差不會超過1 % 。 -
This paper can be mainly summarized in to three aspects as follows : 1. firstly, the paper analyzes the system model of mimo, derive the formulas of channel capacity for the slow flat rayleigh fading channel, analyzes two improtant facts affected the system capacity, and then via the computer simulation we compare the channel capacity between the tranditonal wireless system and mimo system
本文主要做了以下幾個方面的工作: 1 .分析了mimo系統的通道模型，理論推導了慢衰落平坦瑞利通道下mimo系統的通道容量公式，簡要分析了影響系統容量的兩個重要因素並且通過計算機模擬比較了傳統無線系統與mimo系統之間的通道容量。 -
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。 -
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 -
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。 -
Two sova decoding algorithms in ofdm system based on bpsk modulation with fading channel were presented. one is called bce _ sova, which is based on adaptive blind channel recognization. it can adaptively estimate the channel state information ( csi )
其中一種是基於自適應盲通道識別演算法的sova譯碼演算法（簡稱bce _ sova ） ，該演算法可以自適應地估計通道狀態信息（ channelstateinformation ， csi ） ，由於不用訓練，傳輸時延小，但計算復雜度高。 -
Section 4 researches on pilot symbol aided space - time 2d rake receiver in rayleigh fading channel. two kinds of 2d - rake receivers are proposed, one is the interference zeros force 2d - rake receiver ( zf - 2drake ). simulation results reveal zf - 2drake has the better performance than the conventional 2d - rake receiver
研究了rayleigh通道下2種導頻輔助的空時2d - rake接收機結構:干擾置零2d - rake接收機（ zf - 2drake ）和基於空時通道估計的時空級聯2d - rake接收機（ spce - 2drake ） ，推導了它們的誤碼率性能。 -
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。 -
The simulation channel models include additive white caussian noise channel and multi - path rayleigh fading channel
在模擬模型中，採用加性高斯白噪聲和多徑瑞利衰落兩種通道模型。 -
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。 -
Appropriate data compression methods are needed to assure the random nature of the information source and to enlarge its entropy. in this thesis, first, we present the theory of sess system, then the acquisition method of sess system is discussed in detail, finally, a acquisition model of sess system is built and simulated in the awgn channel, in the raleigh fading channel and in multi - address interfere condition. the simulation results show the acquisition method of sess system can be just as reliable as the conventional dsss systems
本文首先對自編碼擴頻通信的基本原理，自編碼擴頻序列的產生方法及其產生的序列的特性進行了概述，然後詳細討論了直擴通信系統中的擴頻碼的捕獲跟蹤問題，根據自編碼擴頻通信的特點，設計了其捕獲跟蹤方案，並在加性高斯白噪聲通道、瑞利衰落通道和多址干擾情況下進行了模擬。 -
First of all, the characteristics of different adaptive algorithms and equalizers are theoretically researched. then digital microwave communication system model is build by simulink. based on this model, the convergent behavior and bit error rate performance of three equalizers ( nlms, kalman and rls ) are compared in multi - path fading channel
為了達到這個目的，首先需要從理論上對各種自適應均衡演算法以及自適應均衡器的特性進行深入研究;然後利用simulink建立接近實際環境的數字微波通信系統，在多徑衰減通道環境下比較了三種基帶均衡器（ nlms ， kalman和rls ）的收斂特性以及系統誤碼特性，並比較了nlms基帶均衡器和通帶均衡器的性能。 -
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
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