frequency selective system 中文意思是什麼
frequency selective system
解釋
選頻系統-
The system is designed as an all - fiber system, using the chirp grating as the frequency - selective element
實驗測得環鏡的溫度靈敏度系數為0 . 92nm / 。 -
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。 -
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。 -
Ruilan s bws3500 broadband wireless access system is capable of solving effectively the fundamental problem of selective frequency attenuation caused by multi - path interference. therefore, it is capable of providing generalized access ( non line - of - sight or quasi line - of - sight transmission )
瑞瀾公司的bws3500寬帶無線接入系統可有效地解決多徑干擾引起的「選頻衰落」這一根本性問題，因此能夠實現普遍化的接入（非視距或準視距傳輸） 。 -
With the downlink simulation model constructed, performance of wideband cdma under different radio propagation environment and vehicular speed is simulated. based on system model of mc ds cdma under flat fading channel with relative shifts of spreading sequences within 1 chip and frequency selective fading channel with arbitrary relative chip shifts, performance of multicarrier cdma system with go sequences under different radio environment is investigated
基於多載波直接序列碼分多址在乎坦衰落通道中序列偏移小於1個碼片及在頻率選擇性衰落通道中偏移任意個碼片的系統模型，本文還分析了採用廣義正交序列的多載波碼分多址系統在不同無線傳播環境下的性能。 -
Finally, performance of adaptive modulation and coding in 11sdpa system is investigated. multi - code channel structure of physical layer, coded modulation schemes and adaptive transmission parameter selection are analyzed. simulation implementation of fading compensation in flat fading channel and maximum ratio combining ( mrc ) in frequency selective fading channel is investigated
最後，本文還研究了hsdpa中自適應調制與編碼性能，分析了物理層多碼通道結構、編碼調制方案、自適應傳輸參數選擇，並研究了平坦和頻率選擇性衰落通道中衰落補償和最大比合併（ mrc ）的模擬實現。 -
Frequency - selective fading due to multipath propagation is a big obstacle in wireless communication. in the condition, the intersymbol interference ( isi ) comes into being and communication system appears error received symbol
多徑傳輸效應引起的頻率選擇性衰落是無線通信的一大障礙，使接收信號產生碼間干擾（ isi ） ，導致通信系統出現誤碼。 -
This article proposes the adaptive algorithm based on equal snr signal noise ratio, and applies it in adaptive ofdm system. in frequency selective fading channel, compared with the traditional ofdm system based on equal power allocation, the system outperforms in ber bit error ratio performance
提出了一種基於最小平均誤碼率的自適應預處理演算法，並將該演算法應用於自適應ofdm系統，在頻率選擇性衰落通道條件下，與等功率分配的ofdm系統相比，誤比特性能有了很大程度的提高。 -
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。 -
So far, there is not much research on the signal detection of da - mimo system, and the general frequency selective channel is not taken into consideration. in chapter 3 of this dissertation, the coherent signal detection algorithms for da - mimo system under both flat fading and frequency selective fading channels are derived. and the analysis of the factors which affect the performance of the detection algorithms is also illustrated through computer simulations
針對分佈mimo信號檢測目前研究較少，並且沒有考慮一般意義下的頻率選擇性通道的情況，本文在第三章分別推導了基於平坦衰落和頻率選擇性衰落通道環境的分佈mimo信號相干檢測演算法，並通過計算機模擬，對影響演算法檢測性能的因素進行了分析討論。 -
Space - time block codes ( stbc ) based on orthogonal design has attracts enough attentions in its applications in mimo - ofdm systems for its full diversity exploiting and low coding / decoding complexity. these applications include not only system performance improvement, but also reduction of the peak to average power ratio in mimo - ofdm systems. under these backgrounds, this paper first studies space - time block codes under the single carrier, flat fading situation, discusses the encoding / decoding principle and its performance under different channels. then, the author focused on the performance of space - time codes under time selective and frequency selective channels, uncovered the fundamental cause of how maximum doppler shift and power delay profile influences the performance of space - time codes through deduction and simulation
在上述背景下，本文以單載波，平坦衰落通道下的空時分組碼為切入點，深入分析了其編譯碼原理和在不同通道情況下的性能;以此為基礎，後文展開了對空時分組碼在多載波，時間選擇性和頻率選擇性衰落通道下的性能研究，通過理論推導和充分的模擬，揭示了空時/頻分組碼在時頻選擇性衰落通道中的性能變化的根本原因;在以上對多載波系統中空時分組碼的研究的過程中，作者發現了空時分組碼在降低系統峰平比方面應用的可行性，提出了一種降低峰平比的新方法。
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