Fractional Fourier Transform Based Secure Communication System

2010 ◽  
Author(s):  
Xin Qiu ◽  
Xue-jun Sha ◽  
Qing-hua Shen ◽  
Xuan-li Wu
Keyword(s):  
Fourier Transform ◽  
Communication System ◽  
Secure Communication ◽  
Fractional Fourier Transform

scholarly journals A fractional Fourier transform–based channel estimation algorithm in single-carrier direct sequence code division multiple access underwater acoustic communication system

2019 ◽  
Vol 15 (1) ◽  
pp. 155014771982600 ◽  
Author(s):  
Lin Zhou ◽  
Qingsheng Zhao ◽  
Shukai Chi ◽  
Yanlong Li ◽  
Lanjun Liu ◽  
...  
Keyword(s):  
Fourier Transform ◽  
Communication System ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Fractional Fourier Transform ◽  
Direct Sequence ◽  
Underwater Acoustic ◽  
Single Carrier ◽  
Sequence Code ◽  
Code Division Multiple

Due to the complexity and variability of the underwater acoustic channel, the communication signal is affected by multi-path, time delay, and Doppler frequency shift. Based on the advantageous characteristics of fractional Fourier transform on chirp signal processing, a fractional Fourier transform–based algorithm using combined linear frequency–modulated signal is proposed, which can estimate parameters of underwater acoustic channel and has a better performance than the existing methods. To distinguish multi-user in underwater acoustic communication system, a single-carrier direct sequence code division multiple access communication system combined with the fractional Fourier transform–based algorithm is proposed. Thus, a preliminary study on underwater multi-target identification is carried out. The simulation and experimental results show that the fractional Fourier transform–based algorithm is simple and effective, and the energy can be focused at the “best” fractional order, which can directly determine the multi-path number and complete the channel estimation. The proposed single-carrier direct sequence code division multiple access communication system has good performance on bit error rate when we use corresponding spreading code to distinguish multi-user.

scholarly journals PHY-Aided Secure Communication via Weighted Fractional Fourier Transform

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Lei Ni ◽  
Xinyu Da ◽  
Hang Hu ◽  
Yuan Liang ◽  
Ruiyang Xu
Keyword(s):  
Fourier Transform ◽  
Secure Communication ◽  
Fractional Fourier Transform ◽  
Satellite Communications ◽  
Unitary Matrix ◽  
Secret Key ◽  
Security Enhancement ◽  
System A ◽  
Signal Characteristics ◽  
Encryption Method

A weighted fractional Fourier transform (WFRFT) based on channel state information (CSI), aiming to safeguard the physical (PHY) layer security of wireless communication system, is proposed. With the proposed scheme, WFRFT is first applied to satellite communications such that the transmitted signal is distorted and can only be neutralized by inverse-WFRFT with the same parameter. Moreover, by exploiting the physical properties of wireless channels, the CSI matrix is transformed as a secret key. In addition, by adding phase rotation (PR) factors to each branch of the WFRFT system, a new unitary matrix with the encryption properties is constructed, and hence, the satellite communications secrecy is reliably guaranteed due to the variation in signal characteristics. Finally, the efficacy of the security enhancement is evaluated in terms of the average bit error rate (BER) and the secrecy capacity. Simulation results show that the proposed encryption method can make the detection and demodulation more difficult for the eavesdropper.

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