spread fading channel 中文意思是什麼
spread fading channel
解釋
擴散衰落通道-
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。 -
Rtce is based on forecasting the inherent vulnerabilities to propagation of hf time - varying channel, including multipath delay, doppler spread, selective fading, interference, so this paper also introduces characteristics of hf channel in the beginning. familiar rtce systems all adopt envelope method that bello brought forward
實時選頻技術是基於對短波電離層時變通道固有的不利於電波傳播的各種因素，包括通道的多徑展寬、多普勒展寬、選擇性衰落、噪聲干擾等的預測的基礎上實現的，所以在開篇對短波通道的特點進行了詳細的介紹。 -
It has been proven that the spread spectrum technologies have good capabilities of overcoming isi in electromagnetic wireless channel. the feasibilities of their applications to underwater acoustic channel have been analyzed, the frequency hopping technology is chosen. instead of using time - frequency diversity, convolutional coding and viterbi decoding are employed to combat signal fading, consequently the bit - rate and bit - error - rate performance of the underwater acoustic voice communication system can be balanced and controlled
由於擴頻技術在抗碼間干擾方面具有優良的特性，因此在分析了各種擴頻技術于本研究應用的可行性之後，確定了跳頻技術作為具體實現方案；在克服幅度衰落方面，選用卷積編碼和維特比譯碼方法來替代原有的分集技術以綜合調節系統的通信速率與誤碼性能，達到差錯可控的目的。 -
Simulator presented in this paper provides a direct interface for the test of shortwave communication system, which well represents various features of hf channel such as multi - path delay, rayleigh fading, doppler shift, doppler spread, gaussian noise and impulsive interference, etc. in order to realize the channel simulation for the intermediate frequency signal, we, inspired by the idea of soft - defined radio, bring forward a new design method that the channel simulator consists of several dsp chips
本文研製的模擬器提供介面直接對短波通信系統進行測試，能夠全面反映短波通道的多徑時延、瑞利衰落、多普勒頻移、多普勒擴展、高斯噪聲和脈沖干擾等特性。為了實現對中頻信號的通道模擬，開發出一個結合軟體無線電思想的由多個數字信號處理晶元構成的短波通道物理模擬器。 -
Because using ofdm, a frequency - selective fading channel can be transformed into multiple frequency - flat fading sub - channels, in the coding process, spatial diversity ( due to multiple antennas ) is integrated with frequency diversity ( due to delay spread ), therefore, the proposed code can provide higher diversity gain than space - time code alone
該編碼利用正交頻分復用把頻率選擇性衰落通道變換成平衰落通道的特性，同時引入了基於多天線的空間分集和基於時延擴展的頻率分集，比空時編碼具有更高的分集增益。 -
The theoretical results are evaluated by simulation. if the coherent bandwidth of channel doesn ’ t exceed the occupied bandwidth of two chips, with the increase of delay spread of the channel, mc - ss - cldd exhibits a better performance to make the system resistant to frequency - selective fading
研究結果表明，多載波擴頻碼片級差分檢測在單用戶和多用戶情況下，均適合於時變頻率選擇性衰落通道，並具有抵抗頻率選擇性衰落的能力。 -
New algorithm and new structure have been developed to make the equalizer to get better performance on combating with seriously distorted channel fading : strong echo fading, large delay spread static and dynamic echo fading. main contents of this paper are as follow : in the first chapter, the history > present situation of the dtv system is presented. five dtv terrestrial broadcasting systems are introduced and two of them are compared, e. g
本文主要內容如下：第一章概述了數字電視技術的發展歷史和目前的狀況，給出了目前已經成型的5種地面廣播標準；對兩種比較典型的傳輸標準： dvb - t和atsc作了性能對比分析，並將比較的焦點集中到對抗強多徑衰落和長時延的靜態和動態多徑衰落的性能上。 -
The closed - form performance formulae of cck modulation are derived under awgn channel and rayleigh fading channel, whose validity is proved by simulations. multi - carrier wideband cdma architecture based on complete complementary codes spread ( ccc - cdma ) has high spectrum efficiency without mai theoretically, which meets the general requirements of b3g communications
研究了高速無線局域網ieee802 . 11b中的基帶技術，特別是基於互補碼擴頻的cck調制，推導出其在高斯噪聲通道和在多徑衰落通道條件下的性能公式。
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