本文選題：認(rèn)知無(wú)線電 + 頻譜感知��； 參考：《華中科技大學(xué)》2014年博士論文

【摘要】：在過(guò)去的幾十年,無(wú)線通信技術(shù)飛速發(fā)展,涌現(xiàn)出越來(lái)越多的新技術(shù),同時(shí)對(duì)頻譜資源的需求也越來(lái)越高。隨著頻譜資源的短缺狀況越來(lái)越明顯,認(rèn)知無(wú)線電技術(shù)越來(lái)越受到人們的關(guān)注。通過(guò)允許認(rèn)知無(wú)線電用戶租用授權(quán)用戶的頻譜資源,或者授權(quán)用戶將其頻譜資源共享給認(rèn)知無(wú)線電用戶使用,認(rèn)知無(wú)線電技術(shù)將大大提高頻譜的利用效率。在認(rèn)知無(wú)線電技術(shù)中,關(guān)鍵技術(shù)之一是頻譜感知技術(shù)。本論文研究如何利用循環(huán)平穩(wěn)特征進(jìn)行授權(quán)用戶信號(hào)檢測(cè),其主要貢獻(xiàn)如下： (1)由于具備恒虛警率性質(zhì)以及低信噪比狀況下仍保持較好的檢測(cè)性能,Dandawate-Giannakis算法在許多循環(huán)平穩(wěn)頻譜感知方法中得到廣泛的應(yīng)用。這是一種廣義似然比檢驗(yàn)算法,其假定循環(huán)自相關(guān)估計(jì)的分布在無(wú)效假設(shè)和備擇假設(shè)上具有相同的漸近協(xié)方差。事實(shí)上,本論文通過(guò)研究揭示：在頻譜感知領(lǐng)域這樣的假設(shè)并不完全正確。本文推導(dǎo)了在頻譜感知中的廣義似然比檢驗(yàn)統(tǒng)計(jì)量,并給出其漸近分布,證明其依然具備恒虛警率的特性。仿真結(jié)果表明,本文提出的廣義似然比算法在檢測(cè)性能上優(yōu)于Dandawate-Giannakis算法。 (2)本文將所提出的廣義似然比檢驗(yàn)算法擴(kuò)展到多天線頻譜感知。通過(guò)將各個(gè)天線自身的循環(huán)自相關(guān)以及任意一對(duì)天線間的循環(huán)互相關(guān)納入檢驗(yàn)算法,使其檢驗(yàn)性能較單天線環(huán)境有明顯提高。仿真結(jié)果證實(shí)了該方法的有效性。本文還將多天線廣義似然比算法和直接多天線擴(kuò)展Dandawate-Giannakis算法進(jìn)行了對(duì)比,驗(yàn)證了本文所提方法的優(yōu)勢(shì)。 (3)大部分通信調(diào)制信號(hào)(如BPSK、QPSK)的循環(huán)自相關(guān)在正負(fù)循環(huán)頻率上是共軛的,由于它們?cè)趯?shí)際的通信環(huán)境中所受到的噪聲和多徑衰落影響一般相互獨(dú)立,因此可以將這一特性運(yùn)用于頻譜感知以提高檢驗(yàn)性能。本文給出了多徑衰落情況下雙循環(huán)頻率的循環(huán)自相關(guān)函數(shù),并將Dandawate-Giannakis算法擴(kuò)展到雙循環(huán)頻率循環(huán)平穩(wěn)特征頻譜感知中,以獲得頻率分集效果。仿真結(jié)果表明,本文提出的方法較單頻率循環(huán)平穩(wěn)頻譜感知性能有明顯提高。 (4)本文提出了一種在正交頻分復(fù)用信號(hào)中采用跳頻子載波的循環(huán)平穩(wěn)特征簽名方法,在頻率選擇性衰落信道中具有高可檢測(cè)性,并具備很低的開(kāi)銷。
[Abstract]:In the past few decades, wireless communication technology has developed rapidly, and more and more new technologies have emerged. At the same time, the demand for spectrum resources is becoming more and more high. As the shortage of spectrum resources becomes more and more obvious, cognitive radio technology is getting more and more attention. By allowing users to rent the spectrum resources of authorized users. Source, or authorizing users to share their spectrum resources to cognitive radio users, cognitive radio technology will greatly improve the efficiency of spectrum utilization. In cognitive radio technology, one of the key technologies is spectrum sensing technology. This paper studies how to use cyclostationary features to carry out authorized user signal detection, the main contributions of this paper are as follows: Below:
(1) the Dandawate-Giannakis algorithm has been widely used in many cyclostationary spectrum sensing methods because of the constant false alarm rate and good detection performance under low SNR conditions. This is a generalized likelihood ratio test algorithm, which assumes that the distribution of the cyclic autocorrelation estimator is on the invalid hypothesis and the alternative hypothesis. The same asymptotic covariance. In fact, this paper reveals that the hypothesis in the domain of spectrum sensing is not completely correct. This paper derives the generalized likelihood ratio test statistics in spectrum sensing, and gives its asymptotic distribution, proving that it still possesses the characteristic of constant false alarm rate. The simulation results show that the generalized similarity of this paper is shown in this paper. The algorithm is superior to the Dandawate-Giannakis algorithm in terms of detection performance.
(2) this paper extends the proposed generalized likelihood ratio test algorithm to multi antenna spectrum sensing. By incorporating the cyclic autocorrelation of each antenna itself and the cyclic cross correlation of any pair of antennas into the test algorithm, the test performance is significantly higher than that of the single antenna environment. The simulation results confirm the effectiveness of the method. This paper will also prove the validity of the method. The multi antenna generalized likelihood ratio algorithm is compared with the direct multi antenna extended Dandawate-Giannakis algorithm, which verifies the advantages of the proposed method.
(3) the cyclic autocorrelation of most communication modulation signals (such as BPSK, QPSK) is conjugated on the positive and negative cycle frequency. Because of their noise and multipath fading in the actual communication environment, they are generally independent. Therefore, this characteristic can be applied to spectrum sensing to improve the performance of the test. This paper gives the multipath fading situation. The cyclic autocorrelation function of the lower double cycle frequency and the Dandawate-Giannakis algorithm are extended to the frequency spectrum sensing of the double loop frequency cyclostationary feature to obtain the frequency diversity effect. The simulation results show that the proposed method is better than the stationary frequency spectrum sensing performance of the single frequency cycle.
(4) this paper proposes a cyclostationary signature scheme using frequency hopping subcarriers in orthogonal frequency division multiplexing (fwdm) signals, which has high detectability in frequency selective fading channels and has very low overhead.
【學(xué)位授予單位】：華中科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN925

【參考文獻(xiàn)】

相關(guān)期刊論文 前2條

1 陳星;賀志強(qiáng);吳偉陵;;基于循環(huán)平穩(wěn)的多天線感知無(wú)線電頻譜檢測(cè)[J];北京郵電大學(xué)學(xué)報(bào);2008年02期

2 楊小牛;;從軟件無(wú)線電到認(rèn)知無(wú)線電,走向終極無(wú)線電——無(wú)線通信發(fā)展展望[J];中國(guó)電子科學(xué)研究院學(xué)報(bào);2008年01期

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本文編號(hào)：2043922