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

【摘要】：隨著無線通信技術(shù)的飛速發(fā)展,相關(guān)的設(shè)備和應(yīng)用也與日俱增,同時(shí),有限的無線頻譜資源也變得日趨緊張,越來越難以滿足日益增長的用戶需求。另一方面,在現(xiàn)有的機(jī)制下,許多無線頻譜資源被授權(quán)給了特定的用戶卻并沒有得到很好的利用,大量的授權(quán)頻譜由于授權(quán)用戶的不存在或是不活動(dòng)被閑置從而造成了頻譜資源的浪費(fèi)。為了解決這一矛盾,Mitola博士于1999年提出了認(rèn)知無線電的概念,通過動(dòng)態(tài)頻譜接入使得感知用戶可以使用閑置的授權(quán)頻段的頻譜資源,從而提升頻譜的利用率,緩解頻譜資源緊張問題。 頻譜感知在認(rèn)知無線電系統(tǒng)中是一種基礎(chǔ)且重要的功能,認(rèn)知無線電系統(tǒng)的正常工作依賴于可靠的頻譜感知結(jié)果,因此如何提升頻譜感知的可靠性一直以來都是研究領(lǐng)域的重點(diǎn)。干擾是無線通信領(lǐng)域中的一個(gè)常見共性問題,在認(rèn)知無線電系統(tǒng)中若存在無線干擾則授權(quán)用戶和感知用戶的正常通信均會(huì)受到影響。為保證系統(tǒng)能夠應(yīng)對(duì)復(fù)雜的無線通信環(huán)境,一個(gè)完整的認(rèn)知無線電系統(tǒng)需要具備檢測當(dāng)前是否存在干擾的能力。圍繞上述內(nèi)容,本論文從以下三個(gè)方面開展相關(guān)的研究工作： 1.在認(rèn)知無線電系統(tǒng)進(jìn)行聯(lián)合頻譜感知時(shí),如果忽視當(dāng)前的網(wǎng)絡(luò)參數(shù)而刻板地使用固定的數(shù)據(jù)融合規(guī)則常常造成感知可靠性不足或是系統(tǒng)開銷過大。針對(duì)這一問題,本文提出了一種聯(lián)合頻譜感知數(shù)據(jù)融合規(guī)則選擇方案。該方案從常用的數(shù)據(jù)融合規(guī)則中選出典型方案組成規(guī)則庫,首先仿真分析在不同網(wǎng)絡(luò)條件下規(guī)則庫中各數(shù)據(jù)融合規(guī)則的性能,再根據(jù)上述結(jié)果設(shè)計(jì)一種能夠根據(jù)當(dāng)前的網(wǎng)絡(luò)環(huán)境選擇感知可靠性最高(若多個(gè)規(guī)則性能相近則選擇響應(yīng)更快的規(guī)則)的數(shù)據(jù)融合規(guī)則的算法。其中,上述算法中的待定參數(shù)通過遺傳算法得出。仿真結(jié)果表明,相比較于使用單一的數(shù)據(jù)融合規(guī)則,利用此數(shù)據(jù)融合規(guī)則選擇方案可以提供更高的頻譜感知可靠性。此外,只需輔以低復(fù)雜度的信任值計(jì)算方法,本方案可以以更短的系統(tǒng)響應(yīng)時(shí)間輸出與其他高復(fù)雜度的方案相似的頻譜感知正確率。 2.基于信任機(jī)制的聯(lián)合頻譜感知中,當(dāng)一個(gè)感知用戶匯報(bào)錯(cuò)誤的本地感知結(jié)果時(shí),數(shù)據(jù)融合中心通常是不分具體原因進(jìn)行統(tǒng)一處理去降低一個(gè)節(jié)點(diǎn)的可信度,這種可信度計(jì)算方法并不能真實(shí)地反映一個(gè)節(jié)點(diǎn)的惡意程度。針對(duì)這一問題,本文提出了一種新的基于信任機(jī)制的聯(lián)合頻譜感知方案。該方案首先依據(jù)各節(jié)點(diǎn)的網(wǎng)絡(luò)環(huán)境估算出相應(yīng)的感知能力值,在此基礎(chǔ)上結(jié)合感知結(jié)果歷史數(shù)據(jù)使用最大似然估計(jì)的方法估算出用戶的可信度,在數(shù)據(jù)融合中心進(jìn)行數(shù)據(jù)融合時(shí)綜合考慮用戶的能力值和可信度輸出最終的聯(lián)合感知結(jié)果。根據(jù)仿真結(jié)果,使用此方案所計(jì)算出的用戶可信度能夠很好地捕捉感知用戶的主觀惡意程度,并且可以有效地提升存在篡改感知數(shù)據(jù)攻擊情況下的頻譜感知正確率。相較于傳統(tǒng)的基于信任機(jī)制的聯(lián)合頻譜感知方案,本方案能提供更高的感知正確率,在最優(yōu)情況下感知正確率最大可以提升約38%。 3.在所有的干擾類型中,學(xué)界普遍認(rèn)為最難以檢測的是被動(dòng)型干擾。若存在被動(dòng)型干擾對(duì)認(rèn)知無線電系統(tǒng)進(jìn)行干擾將對(duì)其正常運(yùn)行帶來極大的危害。針對(duì)這一問題,本文提出了一種針對(duì)被動(dòng)型干擾源的聯(lián)合檢測與定位方案。該方案利用多個(gè)授權(quán)用戶之間的協(xié)作,根據(jù)干擾對(duì)鄰近授權(quán)小區(qū)中授權(quán)用戶的影響建立常態(tài)檔案,然后根據(jù)當(dāng)前測量值與常態(tài)檔案的相似度進(jìn)行被動(dòng)干擾源的檢測,并且在檢測出干擾源存在的情況下可以基于同樣的輸入進(jìn)行對(duì)干擾源的實(shí)時(shí)定位。通過仿真驗(yàn)證,該方案檢測速度較快,并且在最佳狀況下可以實(shí)現(xiàn)被動(dòng)干擾源檢測的虛警概率和漏警概率同時(shí)低于10%,在干擾源定位方面,該方案最差情況下也有70%以上的概率保證干擾源定位誤差在一跳之內(nèi)。 綜上所述,本文以提升認(rèn)知無線電中聯(lián)合頻譜感知的可靠性以及對(duì)干擾源的檢測和定位能力為目標(biāo),從三個(gè)方面對(duì)相關(guān)領(lǐng)域的研究進(jìn)行了補(bǔ)充,其中前兩項(xiàng)研究針對(duì)認(rèn)知無線電中的頻譜感知,后一項(xiàng)研究針對(duì)認(rèn)知無線電中的干擾檢測。
[Abstract]:With the rapid development of wireless communication technology, the related equipment and applications are increasing. At the same time, the limited wireless spectrum resources are becoming increasingly tense, and more and more difficult to meet the growing user needs. On the other hand, under the existing mechanism, many wireless spectrum sources have been authorized to specific users but not very good. In order to solve this contradiction, Dr. Mitola proposed the concept of cognitive radio in 1999. Through dynamic spectrum access, the user can use the spectrum resources of the idle authorized band, from the dynamic spectrum access. And improve the utilization of spectrum, alleviate the problem of spectrum resource shortage.
Spectrum sensing is a fundamental and important function in cognitive radio systems. The normal work of cognitive radio systems depends on reliable spectrum sensing results. Therefore, how to improve the reliability of spectrum sensing has been the focus of the research field. Interference is a common common problem in the field of wireless communication. If there is wireless interference in a wire system, the normal communication between the authorized user and the perceived user will be affected. In order to ensure that the system can cope with the complex wireless communication environment, a complete cognitive radio system needs to have the ability to detect whether there is interference at present. The following three aspects are carried out in this paper. Related research work:
1. when the cognitive radio system is aware of the joint spectrum sensing, if the current network parameters are ignored, the fixed data fusion rules are often used to cause insufficient perceived reliability or excessive system overhead. In this paper, a combination rule selection scheme is proposed in this paper. In the data fusion rules, a typical scheme is selected to form a rule base. First, the performance of the data fusion rules in the rule base under different network conditions is simulated and analyzed. Then a kind of rules which can select the highest perceived reliability according to the current network environment is designed according to the current network environment (if the performance of multiple rules is similar, the rule of faster response is chosen). An algorithm for data fusion rules. Among them, the undetermined parameters in the above algorithm are obtained by genetic algorithm. The simulation results show that compared with the use of a single data fusion rule, this data fusion rule selection scheme can provide higher spectrum sensing reliability. In addition, the method of trust value calculation with low complexity is only necessary. The case can output a shorter system response time and similar spectrum sensing accuracy with other high complexity schemes.
2. in the joint spectrum sensing based on trust mechanism, when a perceived user reports the local perceived result of the error, the data fusion center is usually handled without a specific reason to reduce the credibility of a node. This credibility calculation method does not truly reflect the malicious degree of a node. In this paper, a new spectrum sensing scheme based on trust mechanism is proposed. This scheme first estimates the corresponding perception ability according to the network environment of each node. On this basis, the user's reliability is estimated by using the maximum likelihood estimation method based on the historical data of the perception results, and the data fusion center is used in the data fusion center. According to the simulation results, the user credibility can capture the subjective malicious degree of the perceived user well, and can effectively improve the spectrum perception accuracy in the case of tamper sensing data attack. In the traditional spectrum sensing scheme based on trust mechanism, this scheme can provide higher perception accuracy. In the optimal case, the maximum perception accuracy can be improved by about 38%.
3. among all the types of interference, the most difficult to detect is the passive interference. If there is a passive interference jamming to the cognitive radio system, it will bring great harm to its normal operation. In this paper, a joint detection and location scheme for passive interference source is proposed. Cooperation between multiple authorized users, based on the impact of interference on the influence of authorized users in the neighbouring authorized community, a normal file is set up, then the passive interference source is detected based on the similarity between the current measured value and the normal file, and the real-time determination of the interference source can be carried out based on the same input in the presence of the presence of the interference source. By simulation, it is proved that the detection speed is faster, and the false alarm probability and the leakage probability of the passive interference source detection can be lower than 10% at the best condition. In the worst case of the interference source, the scheme also has more than 70% probability to guarantee the interference source localization error in one jump.
To sum up, in order to improve the reliability of spectrum sensing in cognitive radio and the ability to detect and locate interference sources, the research in the related fields is supplemented from three aspects. The first two studies are aimed at spectrum sensing in cognitive radio, and the latter research is aimed at interference detection in cognitive radio.
【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1條

1 ZENG Kun;PENG QiHang;TANG YouXi;;Mitigating spectrum sensing data falsification attacks in hard-decision combining cooperative spectrum sensing[J];Science China(Information Sciences);2014年04期

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本文編號(hào)：2056120