發(fā)布時間：2018-05-26 18:18

  本文選題：數(shù)字信號 + 語音信道　； 參考：《西安電子科技大學》2014年碩士論文

【摘要】：由于語音通話安全防范措施的缺失,近年來移動端到端的語音通信安全問題已受到越來越多的關(guān)注。通過加密技術(shù)對語音信號進行加密保證了語音信息在移動端到端間通信的安全性以及直接性,由于加解密過程中的操作容易性、加密速度性以及加密穩(wěn)定性等原因,對于數(shù)字語音信號的加密技術(shù)是主要的語音信息的加密方式。需要說明的是,將模擬信號轉(zhuǎn)換成數(shù)字信號是進行數(shù)字語音信號加密前的必要工作。由于通信系統(tǒng)中的數(shù)據(jù)信道無法保證數(shù)字信號傳輸?shù)亩虝r性和實時性,并且會與國際網(wǎng)絡(luò)出現(xiàn)互通問題,因而需要借助語音信道來進行數(shù)字信號的傳輸。語音信道是多用來傳輸話音信號的模擬信道,模擬話音信號與數(shù)字信號在內(nèi)容組成、頻帶范圍等方面存在很大差異,尤其是,模擬語音信號有數(shù)字語音信號所沒有的類似真實語音的特征。語音信道的關(guān)鍵部分是聲碼器,只有具備類語音特征的信號才能較好的通過聲碼器。因此,如果一般的數(shù)字語音信號沒有類似真實語音的特征,那么這種數(shù)字語音信號在通過語音信道的聲碼器時就有可能被當作噪聲而丟棄,從而在接收端對數(shù)字信號進行恢復時產(chǎn)生較大的誤碼,進而對合成語音造成嚴重失真。所以說,如何進行調(diào)制傳輸使數(shù)字信號在語音信道上可靠傳輸,并且保證語音信號的安全性,這才是移動端到端語音信號保密通信的關(guān)鍵技術(shù)。對于在語音信道中傳輸數(shù)字信號過程中出現(xiàn)的問題,我們主要做了以下幾方面的貢獻:(1)利用混合激勵線性預測,也就是MELP(Mixed Excitation Linear Prediction)方式,我們可以通過語音壓縮編碼的方式來對語音信號進行語音壓縮的編碼,在編碼完成后,再進行SM2橢圓曲線公鑰密碼算法方法的加密,這樣便保證了語音信號傳輸過程中的安全性。(2)對于類似真實語音調(diào)制過程中存在的各種各樣的問題,我們提出了在發(fā)送端對所需要發(fā)送的數(shù)字信號進行信道編碼、正交頻分復用(OFDM,Orthogonal Frequency Division Multiplexing)類語音調(diào)制和快速傅里葉變換(FFT,Fast Fourier Transform)插值這三個模塊的處理,通過以上三個模塊的處理,我們便可以優(yōu)化類似真實語音信號調(diào)制的過程,從而使所需傳輸?shù)臄?shù)字語音信號可以具備類似真實語音的特征。也就使語音信號可以在GSM語音信道中可以可靠、穩(wěn)定、安全的傳輸。特別地,本文對OFDM類語音調(diào)制和FFT插值所需要的參數(shù)設(shè)置方法進行了設(shè)計和取值分析。(3)在此基礎(chǔ)上,本文給出了在GSM語音信道中抗聲碼器壓縮的數(shù)字信號安全傳輸?shù)南到y(tǒng)實現(xiàn)方案,并討論了該系統(tǒng)應(yīng)用于3G和4G系統(tǒng)的理論可行性。(4)最后,在MATLAB仿真環(huán)境下對本文所設(shè)計的系統(tǒng)分別在GSM語音信道中和3G語音信道中進行了仿真,并對仿真結(jié)果進行了分析。從我們仿真的結(jié)果可以看出,在GSM語音信道的仿真環(huán)境中,我們利用MELP語音信號壓縮編碼技術(shù)將模擬語音信號轉(zhuǎn)換為數(shù)字語音信號,與此同時將轉(zhuǎn)換后的數(shù)字語音信號通過SM2加密以及類似真實語音的調(diào)制,最后該數(shù)字語音信號能夠以近似真實語音信號的形式在GSM語音信道中傳輸,接收端收到的語音信號的誤碼率也非常小。同樣,在3G語音信道中,采用相同的方法同樣可以將數(shù)字語音信號轉(zhuǎn)換為近似真實語音的信號形式,而且在接收端收到的信號的誤碼率同樣非常小。因此,我們對數(shù)字信號在GSM語音信道中安全可靠的傳輸提供了一種非常可行的算法,并且也同樣適用于3G語音信道。
[Abstract]:In recent years, the security of voice communication in mobile end to end has been paid more and more attention due to the lack of security precautions for voice calls. Encryption technology to encrypt the voice signal to ensure the security and immediacy of the voice information in the mobile end to end communication. Because of the easy operation and encryption in the process of encryption and decryption, the encryption technology is easy to encrypt and encrypt The encryption technology for digital voice signals is the main way to encrypt the main voice information. It is necessary to explain that converting analog signals into digital signals is a necessary work before encrypting digital voice signals. Because the data channel in the communication system can not guarantee the short transmission of digital signals, the data channel in the communication system can not guarantee the short transmission of the digital signal. It is time and real-time, and interworking with international network, so the voice channel is needed to transmit the digital signal. The voice channel is the analog channel used to transmit voice signals, and the analog voice signal and the digital signal are very different in content composition, frequency range and so on, especially, analog voice signal The key part of the voice channel is the characteristic of the real voice. The key part of the speech channel is the vocoder, only the signal with the class voice feature can pass the vocoder. Therefore, if the general digital voice signal is not similar to the true voice, then the digital voice signal is in the voice channel sound. The code device may be discarded as noise, resulting in a larger error in the recovery of the digital signal at the receiving end, and thus causing serious distortion to the synthetic speech. So, how to transmit the digital signal reliably on the voice channel and ensure the security of the voice signal, which is the end to end of the mobile phone. The key technology of the speech signal secret communication is the following contributions: (1) we can use the hybrid excitation linear prediction, that is, the MELP (Mixed Excitation Linear Prediction) mode, and we can use the voice compression coding to make the speech sound. The signal is encoded by the speech compression. After the coding is completed, the SM2 elliptic curve public key algorithm is encrypted, which ensures the security of the speech signal transmission. (2) we propose a digital letter to be sent at the transmitter to the various problems in the similar real voice modulation process. Channel coding, OFDM, Orthogonal Frequency Division Multiplexing class speech modulation and fast Fourier transform (FFT, Fast Fourier Transform) interpolation, the processing of these three modules, through the processing of the above three modules, we can optimize the process of similar real voice signal modulation, thus making it necessary The transmitted digital voice signal can have the characteristics similar to the real voice. It also makes the speech signal reliable, stable and secure in the GSM voice channel. In particular, this paper designs and analyzes the parameter setting methods needed for the OFDM class speech modulation and FFT interpolation. (3) this paper gives the article in this paper In the GSM voice channel, a system implementation scheme for secure transmission of digital signals compressed by a vocoder is proposed, and the theoretical feasibility of the system used in the 3G and 4G systems is discussed. (4) finally, the system designed in this paper is simulated in the GSM voice channel and 3G voice channel under the MATLAB simulation environment, and the simulation results are carried out. From the simulation results, we can see that in the simulation environment of the GSM voice channel, we use the MELP speech signal compression coding technology to convert the analog speech signal to the digital voice signal. At the same time, the converted digital voice signal is encrypted by SM2 and similar to the real voice modulation. Finally, the digital voice signal is used. It can be transmitted in the GSM voice channel in the form of approximate real speech signal, and the error rate of the speech signal received by the receiver is also very small. Similarly, in the 3G voice channel, the same method can be used to convert the digital voice signal to the form of the approximate true voice, and the error rate of the signal received at the receiving end is the same. The sample is very small. Therefore, we provide a very feasible algorithm for the secure and reliable transmission of digital signals in the GSM voice channel, and it also applies to the 3G voice channel.
【學位授予單位】：西安電子科技大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：TN912.3

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本文編號：1938366