異步DS-CDMA系統(tǒng)盲空時(shí)信道估計(jì)及多用戶檢測(cè)
Blind Space-Time Channel Estimation and Multiuser Detection for Asynchronous DS-CDMA System
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摘要: 該文提出了適用于頻率選擇性瑞利衰落信道中的異步DS-CDMA系統(tǒng)盲空時(shí)信道估計(jì)及多用戶檢測(cè)算法。通過研究多徑信號(hào)碼空間和數(shù)據(jù)矢量空間，采用噪聲子空間技術(shù)進(jìn)行異步DS-CDMA系統(tǒng)盲空時(shí)信道參數(shù)估計(jì)，同時(shí)利用了多徑傳播和接收機(jī)同步失調(diào)的特性，以利于把盲線性濾波優(yōu)化技術(shù)應(yīng)用于穩(wěn)健的干擾抑制。使用一種修改的ULV更新算法進(jìn)行噪聲子空間跟蹤，該算法不需要相關(guān)矩陣的秩估計(jì)，直接估計(jì)噪聲子空間，不進(jìn)行信號(hào)子空間跟蹤。并且研究了線性約束最小方差(LCMV)盲空時(shí)多用戶檢測(cè)及其基于Householder變換約束最小均方算法(HCLMS)的自適應(yīng)實(shí)現(xiàn)。仿真結(jié)果驗(yàn)證了該文算法的有效性。
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關(guān)鍵詞:
- DS-CDMA;盲空時(shí)多用戶檢測(cè);空時(shí)信道估計(jì);失配
Abstract: The blind space-time channel estimation and multiuser detection algorithm for asynchronous DS-CDMA system in frequency selective Rayleigh fading channel are presented. By investigating the code space of the multipath signals and the data vector space, the noise-subspace-based approach is used to perform blind channel parameter estimation in the asynchronous DS-CDMA system. The method exploits not only the characteristics of multipath propagation but also the characteristics of timing-offsets which may occur in the receiver, to facilitate the application of a blind linear filter-optimization technique to robust interference suppression. A modified ULV updating algorithm is applied to performing noise subspace tracking. The algorithm does not require rank estimation of the correlation matrix, and estimate directly the noise subspace without tracking the signal subspace. Furthermore, Linearly Constrained Minimum Variance (LCMV) blind space-time multiuser detection and its adaptive implementation based on Householder-transform constrained least-mean-square (HCLMS) algorithm is considered. Simulation results show the effectiveness of the proposed algorithms. -
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