基于壓縮感知和指數(shù)熵的頻譜感知技術(shù)研究
發(fā)布時(shí)間：2019-07-03 15:51
【摘要】：隨著無線通信業(yè)務(wù)的發(fā)展,可利用的頻帶資源變得日益緊張。然而在另一方面,很多已被授權(quán)的頻譜資源的實(shí)際利用率是非常低的。認(rèn)知無線電技術(shù)正是針對這一狀況提出并發(fā)展起來的。在保證授權(quán)用戶的正常通信不被干擾的前提條件下,通過使認(rèn)知用戶動(dòng)態(tài)地接入授權(quán)頻段來提高授權(quán)頻譜的利用率。其中,頻譜感知技術(shù)是認(rèn)知無線電得以實(shí)現(xiàn)的必要條件。首先對認(rèn)知無線電技術(shù)的提出背景以及相關(guān)發(fā)展研究狀況進(jìn)行了介紹,然后分別詳細(xì)討論了基于發(fā)射機(jī)以及基于接收機(jī)的頻譜感知算法的理論模型,并分別對基于匹配濾波器檢測、能量檢測、協(xié)方差矩陣檢測以及循環(huán)平穩(wěn)特征檢測的頻譜感知原理進(jìn)行了詳細(xì)闡述,總結(jié)了其各自的適用場合及優(yōu)缺點(diǎn)。然后針對單用戶頻譜感知的不足,介紹了認(rèn)知無線電系統(tǒng)多用戶合作頻譜感知技術(shù),分別對基于硬判決合作和軟判決合作的融合原理進(jìn)行了分析并討論了其各自優(yōu)缺點(diǎn),給出了相應(yīng)的檢測性能分析。針對在寬帶頻譜感知中按照傳統(tǒng)采樣方式時(shí)數(shù)據(jù)量較大的問題,提出了一種基于壓縮感知和匹配濾波器理論的頻譜感知模型。當(dāng)原始信號(hào)的帶寬很大且可壓縮時(shí),為了節(jié)約信道資源,可以先將原始信號(hào)進(jìn)行壓縮采樣然后再在信道中傳輸。然而在認(rèn)知無線電系統(tǒng)中,認(rèn)知用戶可能不具有很高采樣速率的能力而傳輸?shù)男盘?hào)仍然數(shù)據(jù)量很大,此時(shí)在認(rèn)知用戶處再進(jìn)行二次壓縮采樣,然后根據(jù)匹配濾波器原理生成判決統(tǒng)計(jì)量并進(jìn)行判決。仿真實(shí)驗(yàn)給出了提出算法與傳統(tǒng)能量檢測算法的檢測性能對比,并分別分析了壓縮矩陣參數(shù)對該算法檢測性能與檢測時(shí)效性的影響。另外,針對目前頻譜感知技術(shù)對噪聲功率不確定性的魯棒性較差、在低信噪比情況下的檢測性能不佳等問題,提出了一種基于指數(shù)熵的頻譜感知算法。該方法根據(jù)H0和H1條件下接收信號(hào)頻域幅值分布特性的不同,估計(jì)接收信號(hào)的指數(shù)熵,然后通過與預(yù)設(shè)的門限進(jìn)行比較,進(jìn)而判斷授權(quán)用戶信號(hào)存在與否。該方法具有不需要信號(hào)的先驗(yàn)知識(shí)、抗噪聲功率不確定性以及在低信噪比下可以得到較高檢測概率等優(yōu)點(diǎn)。最后,受基于能量檢測的等增益合并算法的啟發(fā),本文還提出了一種基于軟判決的指數(shù)熵合作檢測方案。仿真實(shí)驗(yàn)表明,提出的基于指數(shù)熵的頻譜感知算法對噪聲功率不確定性具有魯棒性,同時(shí),在低信噪比情況下也具有較好的檢測性能;提出的基于軟判決的多用戶合作指數(shù)熵頻譜感知方案較傳統(tǒng)的硬判決合作頻譜感知方案也具有更好的檢測性能。
[Abstract]:With the development of wireless communication services, the available frequency band resources become increasingly tense. On the other hand, however, many authorized spectral resources have a very low actual utilization. The cognitive radio technology is proposed and developed for this situation. Under the precondition that the normal communication of the authorized user is not disturbed, the utilization rate of the authorized frequency spectrum is improved by dynamically accessing the authorized frequency band by the cognitive user. In which the spectrum sensing technology is a necessary condition for realizing the realization of the cognitive radio. Firstly, the background of the cognitive radio technology and the related development research situation are introduced, then the theoretical model of the frequency spectrum sensing algorithm based on the transmitter and the receiver is discussed in detail, and the detection and the energy detection based on the matched filter are respectively discussed. The spectrum sensing principle of the detection of the covariance matrix and the detection of the smooth characteristic of the loop is described in detail, and their respective application and advantages and disadvantages are summarized. Then, aiming at the shortage of single-user spectrum sensing, the multi-user cooperative spectrum sensing technology of the cognitive radio system is introduced, the fusion principle based on the hard decision cooperation and the soft decision cooperation is analyzed and the respective advantages and disadvantages are discussed, and the corresponding detection performance analysis is given. A spectrum-aware model based on the theory of compression-aware and matched-filter is proposed for the problem of the large amount of data in the wide-band spectrum sensing according to the traditional sampling method. When the bandwidth of the original signal is large and compressible, in order to save the channel resources, the original signal can be compressed and then transmitted in the channel. In the cognitive radio system, however, the signal transmitted by the cognitive user may not have a high sampling rate still has a large amount of data, at which time the secondary compression sampling is performed at the cognitive user, and then the decision statistic is generated and the decision is made according to the matched filter principle. In this paper, the detection performance of the proposed algorithm and the traditional energy detection algorithm is compared, and the influence of the compression matrix parameters on the detection performance and the time-effectiveness of the algorithm is analyzed. In addition, aiming at the problem of poor robustness of the current spectrum sensing technology to the noise power uncertainty, the detection performance under the condition of low signal-to-noise ratio is not good, and the spectrum sensing algorithm based on the index entropy is proposed. The method estimates the index entropy of the received signal according to the difference of the frequency domain amplitude distribution characteristic of the received signal under the condition of H0 and H1, and then judges whether the authorized user signal exists or not by comparing with a preset threshold. The method has the advantages of no prior knowledge of signals, uncertainty of anti-noise power and high detection probability under low signal-to-noise ratio. Finally, an exponential entropy cooperation detection scheme based on soft decision is presented in this paper. The simulation experiment shows that the proposed spectrum-sensing algorithm based on the index entropy is robust to the noise power uncertainty, and also has better detection performance in the case of low signal-to-noise ratio; The proposed soft-decision-based multi-user cooperation index entropy spectrum sensing scheme has better detection performance than the traditional hard-decision cooperative spectrum sensing scheme.
【學(xué)位授予單位】：哈爾濱工程大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN925
本文編號(hào)：2509503
[Abstract]:With the development of wireless communication services, the available frequency band resources become increasingly tense. On the other hand, however, many authorized spectral resources have a very low actual utilization. The cognitive radio technology is proposed and developed for this situation. Under the precondition that the normal communication of the authorized user is not disturbed, the utilization rate of the authorized frequency spectrum is improved by dynamically accessing the authorized frequency band by the cognitive user. In which the spectrum sensing technology is a necessary condition for realizing the realization of the cognitive radio. Firstly, the background of the cognitive radio technology and the related development research situation are introduced, then the theoretical model of the frequency spectrum sensing algorithm based on the transmitter and the receiver is discussed in detail, and the detection and the energy detection based on the matched filter are respectively discussed. The spectrum sensing principle of the detection of the covariance matrix and the detection of the smooth characteristic of the loop is described in detail, and their respective application and advantages and disadvantages are summarized. Then, aiming at the shortage of single-user spectrum sensing, the multi-user cooperative spectrum sensing technology of the cognitive radio system is introduced, the fusion principle based on the hard decision cooperation and the soft decision cooperation is analyzed and the respective advantages and disadvantages are discussed, and the corresponding detection performance analysis is given. A spectrum-aware model based on the theory of compression-aware and matched-filter is proposed for the problem of the large amount of data in the wide-band spectrum sensing according to the traditional sampling method. When the bandwidth of the original signal is large and compressible, in order to save the channel resources, the original signal can be compressed and then transmitted in the channel. In the cognitive radio system, however, the signal transmitted by the cognitive user may not have a high sampling rate still has a large amount of data, at which time the secondary compression sampling is performed at the cognitive user, and then the decision statistic is generated and the decision is made according to the matched filter principle. In this paper, the detection performance of the proposed algorithm and the traditional energy detection algorithm is compared, and the influence of the compression matrix parameters on the detection performance and the time-effectiveness of the algorithm is analyzed. In addition, aiming at the problem of poor robustness of the current spectrum sensing technology to the noise power uncertainty, the detection performance under the condition of low signal-to-noise ratio is not good, and the spectrum sensing algorithm based on the index entropy is proposed. The method estimates the index entropy of the received signal according to the difference of the frequency domain amplitude distribution characteristic of the received signal under the condition of H0 and H1, and then judges whether the authorized user signal exists or not by comparing with a preset threshold. The method has the advantages of no prior knowledge of signals, uncertainty of anti-noise power and high detection probability under low signal-to-noise ratio. Finally, an exponential entropy cooperation detection scheme based on soft decision is presented in this paper. The simulation experiment shows that the proposed spectrum-sensing algorithm based on the index entropy is robust to the noise power uncertainty, and also has better detection performance in the case of low signal-to-noise ratio; The proposed soft-decision-based multi-user cooperation index entropy spectrum sensing scheme has better detection performance than the traditional hard-decision cooperative spectrum sensing scheme.
【學(xué)位授予單位】：哈爾濱工程大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TN925
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