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首頁> 外文學(xué)位 >Interference cancelling receivers with multiple antennas for CDMA systems.
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Interference cancelling receivers with multiple antennas for CDMA systems.

機(jī)譯：用于CDMA系統(tǒng)的具有多個(gè)天線的干擾消除接收機(jī)。

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摘要

The focus of this thesis is on low complexity multiuser receiving schemes for CDMA signals. Several interference cancelling receivers are introduced and it is shown that receivers with multiple antennas can take advantage of the spatial distribution of the users to achieve improved performance.; A single antenna multistage parallel interference canceller is developed, which without adding significant complexity improves on the performance of the conventional matched filter receiver, and in the limit, as the number of stages increases infinitely, becomes near-far resistant. It provides a simple structure for an approximate implementation of the decorrelating detector, where the number of stages can be determined by the performance requirements of the system.; As the number of users in a system with limited bandwidth grows, it becomes necessary to assign signature waveforms which have relatively larger correlations. This motivates the use of multiple antennas at the receiver to provide increased discrimination between the users by exploiting their spatial separation. In addition, beamforming techniques can be used to reduce multiple access interference arriving from directions other than that of the desired user.; A successive interference cancelling scheme with multiple receiving antennas is formulated and the potential enhancement in performance by using antenna arrays is demonstrated. Due to the dynamic nature of cellular communications and severe multipath fading conditions, the array response vectors vary rapidly, making it impossible for the receiver to know their exact value at a given time. In a CDMA environment, the knowledge of the users' signature sequences can be exploited to design blind adaptive schemes for the antenna arrays. Two such schemes have been proposed for the adaptation of the combining as well as cancelling stages, the performances of these schemes are compared and it is shown that without requiring any additional spatial information, this receiver achieves better error performance than its single-element counterpart.; These schemes are extended to provide multipath diversity by constructively combining the replicas of the desired signal arriving from different directions and delays. The performance of one of the blind methods is shown to be close to that of the optimum spatio-temporal multipath combining receiver.
機(jī)譯：本文的重點(diǎn)是針對(duì)CDMA信號(hào)的低復(fù)雜度多用戶接收方案。介紹了幾種干擾消除接收機(jī)，并且表明具有多個(gè)天線的接收機(jī)可以利用用戶的空間分布來提高性能。開發(fā)了一種單天線多級(jí)并行干擾消除器，其在不增加顯著復(fù)雜性的情況下改善了常規(guī)匹配濾波器接收機(jī)的性能，并且在極限上，隨著級(jí)數(shù)的無限增加，其變得近乎抗拒。它為解相關(guān)檢測(cè)器的近似實(shí)現(xiàn)提供了一種簡(jiǎn)單的結(jié)構(gòu)，其中級(jí)數(shù)可以由系統(tǒng)的性能要求確定。隨著帶寬有限的系統(tǒng)中用戶數(shù)量的增長(zhǎng)，有必要分配具有相對(duì)較大相關(guān)性的簽名波形。這激發(fā)了在接收器處使用多個(gè)天線，以通過利用用戶的空間間隔在用戶之間提供更大的區(qū)分度。另外，波束成形技術(shù)可以用來減少來自不同于期望用戶的方向的方向的多址干擾。制定了具有多個(gè)接收天線的連續(xù)干擾消除方案，并演示了使用天線陣列可潛在提高性能。由于蜂窩通信的動(dòng)態(tài)特性和嚴(yán)重的多徑衰落條件，陣列響應(yīng)向量變化很快，從而使接收器無法在給定時(shí)間知道其確切值。在CDMA環(huán)境中，可以利用用戶簽名序列的知識(shí)來設(shè)計(jì)天線陣列的盲自適應(yīng)方案。已經(jīng)提出了兩種這樣的方案用于組合和抵消階段的適應(yīng)，比較了這些方案的性能，并且表明，不需要任何額外的空間信息，該接收機(jī)就比其單元素接收機(jī)具有更好的差錯(cuò)性能。 ;通過構(gòu)造性地組合從不同方向和延遲到達(dá)的所需信號(hào)的副本，擴(kuò)展了這些方案以提供多徑分集。盲法之一的性能顯示出接近最佳時(shí)空多徑組合接收機(jī)的性能。

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  • 作者

    Ghazi-Moghadam, Vafa.;

  • 作者單位

    University of Minnesota.;

  • 授予單位 University of Minnesota.;
  • 學(xué)科 Engineering Electronics and Electrical.
  • 學(xué)位 Ph.D.
  • 年度 1997
  • 頁碼 118 p.
  • 總頁數(shù) 118
  • 原文格式 PDF
  • 正文語種 eng
  • 中圖分類 無線電電子學(xué)、電信技術(shù);
  • 關(guān)鍵詞

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