發(fā)布時間：2018-05-29 17:07

  本文選題：無線物理層安全 + 人工噪聲�。� 參考：《國防科學技術大學》2014年博士論文

【摘要】：無線物理層安全技術利用發(fā)送端到合法用戶的信道和到竊聽者的信道之間的隨機性、差異性和互易性等特性從物理層上實現(xiàn)信息的安全傳輸。它從信息論意義上確保竊聽者無法獲取信源發(fā)送的信息,在抗竊聽、低截獲和無線通信系統(tǒng)設計等領域具有廣闊的應用前景。多天線技術通過利用豐富的空間資源,不僅能夠獲得傳輸?shù)目煽啃院陀行詢煞矫娴膬?yōu)勢,而且自然增加了信道間差異性,為無線物理層安全技術研究提供了廣闊的空間。然而,多天線系統(tǒng)的物理層安全傳輸性能很大程度上依賴于發(fā)送端獲取的信道狀態(tài)信息(Channel State Information,CSI),不同信道信息條件和應用場景下的安全傳輸成為物理層安全技術研究中的關鍵和難點問題,論文圍繞這些關鍵和難點問題展開研究。首先,針對多輸入單輸出(Multiple-input Single-output,MISO)系統(tǒng)中發(fā)送端已知竊聽信道統(tǒng)計信息的情況,論文研究了人工噪聲輔助安全傳輸?shù)墓β史峙鋯栴},提出了一種最小化系統(tǒng)保密中斷概率的最優(yōu)功率分配算法。已有研究證明,在僅有竊聽信道統(tǒng)計信息的情況下,人工噪聲的設計應當正交于主信道,而且系統(tǒng)的安全性能取決于有用信號和人工噪聲間的功率分配。論文推導了保密中斷概率的閉合表達式,并以最小化保密中斷概率為目標設計了最優(yōu)功率分配算法。針對單個具有多天線的竊聽者情況,提出了一種基于Golden搜索的最優(yōu)功率分配算法。針對多個具有單天線的竊聽者情況,提出了一種閉合的最優(yōu)功率分配算法,并將最優(yōu)功率分配算法轉化為一個確定性方程求解,從而推導得到其閉合解。針對上述兩種場景的仿真結果表明所提出的最優(yōu)功率分配算法性能明顯優(yōu)于傳統(tǒng)波束成形算法和等功率分配算法。其次,針對多輸入多輸出多竊聽(Multiple-input Multiple-output Multi-antenna Eavesdropper,MIMOME)模型中發(fā)送端未知竊聽信道信息的情況,論文提出了一種發(fā)送天線選擇(Transmit Antenna Selection,TAS)和最大比合并(Maximal Ratio Combining,MRC)相結合的安全傳輸算法。在這種場景下的安全傳輸設計中,發(fā)送端需要得到合法接收端反饋的最優(yōu)天線系數(shù)。在理想反饋時,系統(tǒng)能夠獲得與未考慮安全性傳輸?shù)膫鹘y(tǒng)多天線系統(tǒng)相同的分集階數(shù),且該分集階數(shù)與竊聽者天線數(shù)目無關。在實際系統(tǒng)中,由于信道反饋延時、信道估計誤差等因素影響,理想反饋幾乎是不可能的。論文分別研究了時延反饋、錯誤反饋以及聯(lián)合時延和錯誤反饋對發(fā)送天線選擇和最大比合并算法安全性能的影響,推導了獲得非零保密傳輸速率的概率和保密中斷概率的閉合表達式。通過分析高信噪比(Signal-to-Noise Ratio,SNR)下的漸近保密中斷概率發(fā)現(xiàn),當出現(xiàn)時延或錯誤等非理想反饋時,來自天線選擇的分集增益將消失,系統(tǒng)僅僅獲得接收端的最大比合并分集增益。所得分析結果更具有一般性,可直接擴展到已有文獻中研究的理想反饋情況。論文通過仿真驗證了理論分析結論的正確性。再次,針對多輸入單輸出的感知無線電網(wǎng)絡(MISO Cognitive Radio Network,MISO-CRN)中發(fā)送端未知竊聽信道信息的情況,論文提出了一種人工噪聲輔助安全傳輸算法。假定網(wǎng)絡中主用戶和次用戶工作于Underlay模式。該算法從用戶服務質(zhì)量(Quality of Service,Qo S)的角度,在保證次用戶(Secondary User,SU)的接收信干噪比(Signal-to-Interference-plus-Noise Ratio,SINR)和主用戶(Primary User,PU)的干擾溫度約束下,最大化人工噪聲的發(fā)送功率。當次用戶發(fā)送端已知主用戶信道信息和次用戶信道信息時,理論證明了波束成形是最優(yōu)的有用信號傳輸策略,此時輸入方差矩陣的秩為1。然而,當次用戶發(fā)送端獲取的信道信息存在誤差時,理想信道條件下設計的人工噪聲策略將產(chǎn)生噪聲泄漏,嚴重影響合法用戶的接收性能。論文假定次用戶發(fā)送端獲取的主用戶信道信息和次用戶信道信息均存在誤差,分別將信道誤差建模為信道矢量誤差模型、信道方差誤差模型和統(tǒng)計信道誤差模型。在信道矢量誤差模型和信道方差誤差模型下,論文提出了一種基于最差性能的魯棒人工噪聲算法,相應的優(yōu)化問題是一個NP-hard(Nondeterministic Polynomial hard)問題�；赟-Procedure引理和凸優(yōu)化理論,論文推導了等效的約束條件,并將原始問題轉化為一個半正定規(guī)劃(Semidefinite Program,SDP)問題,從而得到了最優(yōu)的人工噪聲輸入方差設計。針對統(tǒng)計信道誤差模型,論文提出了一種基于中斷概率約束的魯棒人工噪聲算法,相應的優(yōu)化問題簡化為一個機會約束的非凸問題。借助于Bernstein型不等式,論文將復雜的概率約束條件轉化為一系列確定性不等式,從而獲得了人工噪聲輸入方差的一個近似解。仿真結果表明,提出的魯棒人工噪聲算法在三種信道誤差模型下均有效地降低了信道誤差的影響。最后,針對單向中繼竊聽系統(tǒng)、雙向中繼竊聽系統(tǒng)和MIMO非信任中繼竊聽系統(tǒng)中發(fā)送端已知理想的信道信息情況,論文分別提出了相關的最優(yōu)中繼波束成形算法、中繼聊天安全傳輸算法和目的端干擾輔助安全傳輸算法。在出現(xiàn)單天線竊聽者的單向中繼系統(tǒng)中,目前并沒有合適的算法來計算放大轉發(fā)(Amplifyand-Forward,AF)模式下最大化保密傳輸速率的中繼波束成形矢量。論文首先提出了一種基于分支定界(Branch-and-Bound)的中繼波束成形算法,并理論證明該算法能夠獲得全局最優(yōu)解。考慮到最優(yōu)算法的計算復雜度高,進一步提出了一種基于廣義功率迭代(General Power Iteration,GPI)的次優(yōu)中繼波束成形算法。次優(yōu)算法在每次迭代過程中僅需要計算三個矩陣值,有效地降低了計算復雜度。在雙向中繼竊聽系統(tǒng)中,已有文獻提出的聯(lián)合中繼和干擾節(jié)點選擇算法存在著保密中斷概率隨著信噪比增加而并不趨近于零的問題。為了解決這一問題,論文提出了一種中繼聊天(Relay Chatting,RC)安全傳輸算法。該算法結合了機會中繼選擇和協(xié)作干擾兩方面的優(yōu)勢,通過選擇多個中繼使用分布式波束成形能夠消除對合法接收端的干擾影響,而僅降低竊聽者的接收性能。理論分析和仿真結果表明在高信噪比下,所提中繼聊天安全傳輸算法的保密中斷概率將趨近于零。進一步,在實際系統(tǒng)中,中繼可能是非信任的(即中繼試圖破譯信源發(fā)送信息),此時沒有直傳路徑的MIMO中繼系統(tǒng)并不能進行安全傳輸。針對此場景,論文提出了兩種目的端干擾輔助的安全傳輸算法,即聯(lián)合信源、中繼和目的端的預編碼算法和基于非信任中繼天線選擇算法。在聯(lián)合信源、中繼和目的端的預編碼算法中,提出了一種基于交替迭代的最優(yōu)信源、中繼和目的端預編碼矩陣設計方案來最大化系統(tǒng)保密傳輸速率。其中,最優(yōu)的信源和目的端預編碼矩陣分別通過求解一個凸優(yōu)化問題獲得,而最優(yōu)的中繼預編碼矩陣具有閉合解。在基于非信任中繼天線選擇算法中,根據(jù)不同的應用場景,提出了最優(yōu)策略(Optimal)、最大化非信任中繼SINR策略(Suboptimal I)和最小化非信任中繼SINR策略(Suboptimal II)等多種天線選擇策略。仿真結果表明,提出的聯(lián)合預編碼算法和非信任中繼天線選擇算法極大地提高了系統(tǒng)安全性能。
[Abstract]:The wireless physical layer security technology uses the randomness, diversity and reciprocity between the channel of the legitimate user and the channel of the eavesdropper to secure the safe transmission of information from the physical layer. It ensures that the listener can not obtain the information sent by the source from the information theory, in the anti eavesdropping, low interception and wireless communication system. Design and other fields have broad application prospects. By using rich space resources, multi antenna technology can not only gain the advantages of two aspects of transmission reliability and effectiveness, but also naturally increase the difference between channels and provide a wide space for the research of wireless physical layer security technology. However, the physical layer security of multi antenna systems is also available. The performance of full transmission depends largely on the channel state information obtained by the transmitter (Channel State Information, CSI). Different channel information conditions and secure transmission in the application scene are the key and difficult problems in the research of the physical layer security technology. The thesis focuses on these key and difficult problems. In the single output (Multiple-input Single-output, MISO) system, the information of the eavesdropping channel is known by the transmitter. The paper studies the power allocation problem of the artificial noise assisted security transmission, and proposes an optimal power allocation algorithm to minimize the probability of the system's secrecy interruption. In this case, the design of artificial noise should be orthogonal to the main channel, and the security performance of the system depends on the power allocation between the useful signal and the artificial noise. The paper derives the closed expression of the secrecy interruption probability, and designs the optimal power allocation algorithm for minimizing the secrecy interruption probability. In the case of the eavesdropper, an optimal power allocation algorithm based on Golden search is proposed. A closed optimal power allocation algorithm is proposed for multiple eavesdropper with single antenna. The optimal power allocation algorithm is converted to a deterministic equation and its closed solution is derived. For the two scenarios mentioned above, the optimal power allocation algorithm is derived. The simulation results show that the performance of the proposed optimal power allocation algorithm is obviously superior to the traditional beamforming algorithm and equal power allocation algorithm. Secondly, the paper proposes an unknown eavesdropping channel information for the transmitting terminal in the Multiple-input Multiple-output Multi-antenna Eavesdropper (MIMOME) model. A secure transmission algorithm combined with Transmit Antenna Selection (TAS) and the maximum ratio combination (Maximal Ratio Combining, MRC). In this scenario, the transmitter needs to obtain the optimal antenna coefficients of the legitimate receiver feedback. In ideal feedback, the system can obtain and unconsider security transmission. The traditional multi antenna system has the same diversity order, and the diversity order has nothing to do with the number of eavesdropper antennas. In the actual system, the ideal feedback is almost impossible because of the influence of channel feedback delay, channel estimation error and so on. The effect of antenna selection and the maximum ratio combination algorithm on the security performance is derived. The closed expression of the probability of obtaining non zero secrecy transmission rate and the probability of secrecy interruption is derived. By analyzing the asymptotically secrecy interruption probability under the high signal to noise ratio (Signal-to-Noise Ratio, SNR), the antenna selection is derived from the antenna when there are non ideal feedback such as time delay or error. The diversity gain will disappear and the system only obtains the maximum ratio of the merge diversity of the receiver. The results of the analysis are more general and can be extended directly to the ideal feedback in the existing literature. The correctness of the theoretical analysis is verified by simulation. Thirdly, the perceptual radio network with multiple input and single output (MISO In the case of Cognitive Radio Network, MISO-CRN), an unknown eavesdropping channel information is transmitted at the sending end. This paper proposes an artificial noise assisted security transmission algorithm. It assumes that the primary and secondary users in the network work in the Underlay mode. The algorithm guarantees the secondary user (Secondary User) from the Perspective of the quality of service (Quality of Service, Qo S). Under the interference temperature of the Signal-to-Interference-plus-Noise Ratio (SINR) and the main user (Primary User, PU), the transmission power of the artificial noise is maximized. When the secondary user has known the main user channel information and the sub user channel information, the theory proves that the beamforming is the best useful signal transmission strategy. At this time, the rank of the input variance matrix is 1., however, when the channel information obtained by the secondary user is error, the artificial noise strategy designed under the ideal channel condition will produce a noise leakage, which seriously affects the receiving performance of the legitimate user. The channel error is modeled as the channel vector error model, the channel variance error model and the statistical channel error model respectively. Under the channel vector error model and the channel variance error model, a robust artificial noise algorithm based on the worst performance is proposed, and the corresponding optimization problem is a NP-hard (Nondeterministic Polynomial hard). Based on the S-Procedure lemma and convex optimization theory, the paper derives the equivalent constraint conditions, and transforms the original problem into 1.5 positive definite programming (Semidefinite Program, SDP), thus the optimal artificial noise input variance design is obtained. The robust artificial noise algorithm with the interruption of probability constraints, the corresponding optimization problem is simplified as a non convex problem with a chance constraint. With the help of the Bernstein type inequality, the paper transforms the complex probability constraint conditions into a series of deterministic inequalities, thus obtaining an approximate solution of the input variance of artificial noise. The simulation results show that the proposed method is an approximate solution. The robust artificial noise algorithm can effectively reduce the influence of channel error under three channel error models. Finally, the optimal relay beamforming algorithm is proposed for one way relay eavesdropping system, two-way relay eavesdropping system and MIMO untrusted relay eavesdropping system. In the unidirectional relay system of single antenna eavesdropper, there is no suitable algorithm to calculate the relay beamforming vector maximizing the secure transmission rate in the Amplifyand-Forward (AF) mode. In the branch and bound (Branch-and-Bound) relay beam forming algorithm, it is proved that the algorithm can obtain the global optimal solution. Considering that the computational complexity of the optimal algorithm is high, a suboptimal relay beamforming algorithm based on the generalized power iteration (General Power Iteration, GPI) is proposed. In the process, only three matrix values are calculated, and the computational complexity is effectively reduced. In the bi-directional relay eavesdropping system, there is a problem that the joint relay and interference node selection algorithm proposed in the literature has the problem that the probability of secrecy interrupts is not close to zero with the increase of signal to noise ratio. (Relay Chatting, RC) secure transmission algorithm. This algorithm combines the advantages of two aspects of opportunity relay selection and cooperative interference. By selecting multiple relays, distributed beamforming can eliminate the interference effect on the legitimate receiver, and only reduce the receiver performance of the eavesdropper. In the actual system, the relay may be untrustworthy (that is, the relay is trying to break the message from the source), and the MIMO relay system without direct path can not be transmitted safely at this time. In this scenario, two kinds of destination interference assistance are proposed in this paper. The secure transmission algorithm, namely, the precoding algorithm of the joint source, relay and destination and the algorithm based on the untrusted relay antenna selection. In the precoding algorithm of the joint source, relay and destination, an alternative iterative optimal source, relay and destination precoding matrix are proposed to maximize the secure transmission of the system. Rate. Among them, the optimal source and destination precoding matrix are obtained by solving a convex optimization problem, and the optimal relay precoding matrix has closed solutions. Based on the different application scenarios, the optimal strategy (Optimal) and the maximization of the untrusted relay SINR strategy (Suboptim) are proposed. Al I) and the minimization of a variety of antenna selection strategies such as the untrusted relay SINR strategy (Suboptimal II). The simulation results show that the proposed joint precoding algorithm and the untrusted relay antenna selection algorithm greatly improve the system security performance.
【學位授予單位】：國防科學技術大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：TN915.08

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