發(fā)布時(shí)間：2019-05-08 23:03

【摘要】：波束成形作為智能天線(xiàn)中的關(guān)鍵技術(shù),可以有效地解決頻譜資源匱乏的問(wèn)題。它在通信系統(tǒng)中引入了空時(shí)處理的自由度,利用用戶(hù)信號(hào)到達(dá)方向的不同,采用空分多址,將同時(shí)、同頻、同碼的信號(hào)區(qū)分開(kāi)了,大幅度地提高了頻譜利用率,擴(kuò)展了系統(tǒng)容量。然而波束成形的精度會(huì)受到噪聲的干擾,在低信噪比下,陣列的性能和輸出信噪比會(huì)大幅度下降,陣列天線(xiàn)形成的波束已經(jīng)不能準(zhǔn)確地對(duì)準(zhǔn)期望用戶(hù)的方向,波束成形就失去了在空域上分離用戶(hù),并且抑制干擾的作用。因此,在低信噪比下提高波束成形的準(zhǔn)確度就成為一個(gè)值得研究的課題。針對(duì)以上問(wèn)題,本論文將研究基于隨機(jī)共振波束成形結(jié)構(gòu)和算法。在提出的結(jié)構(gòu)中,接收信號(hào)先經(jīng)過(guò)隨機(jī)共振系統(tǒng)的處理,將淹沒(méi)在強(qiáng)噪聲背景中的微弱信號(hào)提取出來(lái),然后進(jìn)行自適應(yīng)的波束成形算法。針對(duì)隨機(jī)共振系統(tǒng)對(duì)采樣率較高的要求,本文主要研究在高頻段(3~30M)的波束成形問(wèn)題。本文的主要內(nèi)容為以下幾個(gè)方面:1本文先詳細(xì)介紹了基于朗之萬(wàn)方程的隨機(jī)共振系統(tǒng)模型,并對(duì)隨機(jī)共振的理論分析做了詳細(xì)介紹。2由于絕熱近似理論下的非線(xiàn)性隨機(jī)共振系統(tǒng)(參數(shù)a=1 b=1)在檢測(cè)微弱信號(hào)時(shí)受小頻率參數(shù)的約束,給實(shí)際應(yīng)用帶來(lái)很大困難。針對(duì)這一情況,提出二次采樣方法和調(diào)整系數(shù)法來(lái)檢測(cè)任意大頻率的微弱信號(hào)。以調(diào)節(jié)參數(shù)雙穩(wěn)態(tài)系統(tǒng)的基礎(chǔ)上,研究了雙穩(wěn)態(tài)系統(tǒng)參數(shù)和信號(hào)頻率之間的相互關(guān)系。對(duì)于淹沒(méi)在噪聲中的不同頻率的輸入信號(hào),提出一種自適應(yīng)調(diào)節(jié)參數(shù)的方法,使輸入信號(hào)頻率和雙穩(wěn)態(tài)系統(tǒng)達(dá)到最佳共振效果。3本文詳細(xì)介紹了自適應(yīng)波束成形的概念、算法準(zhǔn)則和常用算法。重點(diǎn)介紹并推導(dǎo)了兩種CDMA系統(tǒng)中的多目標(biāo)自適應(yīng)解擴(kuò)重?cái)U(kuò)波束成形算法。4在以上研究的基礎(chǔ)上,本文提出了一種自適應(yīng)的陣列天線(xiàn)信號(hào)處理結(jié)構(gòu),將自適應(yīng)隨機(jī)共振應(yīng)用在多目標(biāo)自適應(yīng)解擴(kuò)重?cái)U(kuò)波束成形算法中,通過(guò)仿真在極低信噪比下使算法性能得到大幅度提高。
[Abstract]:Beamforming, as the key technology of smart antenna, can effectively solve the problem of lack of spectrum resources. It introduces the degree of freedom of space-time processing in the communication system, makes use of the different direction of arrival of the user signal, adopts the space division multiple access, distinguishes the signals of the same frequency and the same code at the same time, and greatly improves the spectrum utilization. The system capacity is expanded. However, the precision of beamforming will be interfered by noise. At low SNR, the performance and output signal-to-noise ratio (SNR) of the array will be greatly reduced, and the beam formed by the array antenna will no longer be able to accurately target the direction of the desired user. Beamforming loses the role of separating users in spatial space and suppressing interference. Therefore, improving the accuracy of beamforming at low signal-to-noise ratio becomes a subject worth studying. In order to solve the above problems, this paper will study the structure and algorithm based on stochastic resonance beamforming. In the proposed structure, the received signal is processed by stochastic resonance system, and the weak signal submerged in the strong noise background is extracted, and then an adaptive beamforming algorithm is carried out. In order to meet the requirement of high sampling rate for stochastic resonance system, the beamforming problem in high frequency band (3 鈮，

本文編號(hào)：2472292