Embedding WFRFT Signals Into TDCS for Secure Communications

Da, Xinyu; Liang, Yuan; Hu, Hang; Xu, Ruiyang; Ni, Lei; Zhai, Dong; Pan, Yu

doi:10.1109/access.2018.2872936

Cited by 12 publications

(6 citation statements)

References 20 publications

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“…The WFRFT-based system can be regarded as the convergence of Multi-Carrier (MC) and Single Carrier (SC) systems, and can be compatible with the current communication systems [2], [3], such as Single Carrier with Frequency Domain Equalization (SC-FDE), Orthogonal Frequency Division Multiplex(OFDM) and Long Term Evolution (LTE) [4]. The WFRFT-based system has the property to make the original signal bit energy distributed in frequency-time domain [2], and exhibits better performance on anti-interference [5]- [8] and anti-interception abilities [9]- [13] than other MC or SC systems. Since WFRFT-based system can be regarded as a novel hybrid carrier scheme that can converge the current SC and MC schemes [2], it's difficult to recognize the WFRFT signals by using the traditional recognition methods that apply to the SC and MC modulation recognitions.…”

Section: Introductionmentioning

confidence: 99%

Novel Modulation Recognition for WFRFT-Based System Using 4th-Order Cumulants

et al. 2019

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We present a novel modulation recognition for weighted-type fractional Fourier transform (WFRFT)-based systems using the fourth-order cumulants. First, the constellation characteristics of the basic digital modulations ASK, PSK, and QAM are analyzed, and the corresponding relationships between the neighboring constellation points' distance and the constellation size are deduced. Second, the closed-form expressions of the fourth-order cumulants (C 42) for the WFRFT-based systems with ASK, PSK, and QAM are derived. Finally, through the first-and second-order derivatives of the C 42 , we prove that the optimal WFRFT order α r can be obtained through the minimization of the C 42. The simulation results show that the novel recognition for the WFRFT-based system is feasible and can reach an accuracy of almost 90% when energy per bit-to-noise power spectrum density ratio (E b /N 0) is greater than 6. INDEX TERMS Weighted-type fractional Fourier transform (WFRFT), modulation recognition, order optimization using 4th-order cumulants.

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Section: Introductionmentioning

confidence: 99%

Novel Modulation Recognition for WFRFT-Based System Using 4th-Order Cumulants

et al. 2019

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“…Эти операции выполняются БПФ-процессорами. Сегодня наблюдается заметный всплеск интереса к CCSK: для вышеназванных применений [12], для перспективной технологии TDCS [13] и в системах спутниковой навигации [14].…”

Section: модуляция циклическим сдвигом кода и многопользовательский п...unclassified

M-Ary Cdma Scheme With CCSK Modulation and Parallel Interference Cancellation Technique

Гепко¹

2022

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In this paper, we tackle the problem of implementation a parallel interference cancellation scheme for multi-user detection (MUD) in M-ary CCSK-modulated CDMA system. Complexity remains the main obstacle to the practical implementation of MUD and a factor limiting, if not the very possibility, then the feasibility of using high order M-ary modulation formats for applications such as low-probability-of-intercept systems with a large spreading factor or, myriads of small self-powered IoT devices. The design of MUD algorithms for M-ary systems leads to a new round of growth in the receiver complexity comparing with the binary modulation. Demodulator has a major impact on the complexity of CDMA system. Cyclic code-shift keying (CCSK) is a modulation technique which is designed to reduce the complexity of M-ary signaling. In this, each symbol is a circularly shifted version of a single code sequence. Assuming synchronization, the receiver cyclically correlates the input signal plus noise with the base sequence and estimates the position of the correlation peak. The preliminary stage of the proposed scheme is a conventional multi-channel CDMA receiver. The preliminary estimates of the data is multiplied by user codes and amplitude estimates in the spreader, and then fed to the adder to generate the MAI estimates. After the latter are subtracted from the group signal, K-dimensional vector of cleared user signals is passed to the matched filter bank to form the refined estimates of the data. At each subsequent stage, the estimates of the output data of the previous stage are used as input data. The complexity gain is the ratio of the number of computations for finding cyclic convolution and, the amount of computations for finding M linear convolutions, i.e., M/log2M. Since the performance of the algorithm is sensitive to the reliability of the preliminary decisions, there are strict criteria for the selection of spreading codes: the length which must be an integer power of 2, the large family size, good periodic autocorrelation and good cross-correlation properties. To examine the proposed algorithm using computer simulation, we selected minimax periodic and odd-periodic complementary codes, the properties of which are close to the properties of the codes used in the CCSK scheme implemented in Link-16 protocol tactical data networks JTIDS and MIDS. Our study shows that the gain over the conventional receiver increases as the SNR increases, achieving 15 dB for BER 10-5. The system with complementary codes outperform system based on minimax PN-codes, achieving a target bit error rate at a lower SNR.

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“…Equations (23), (24), (25), and (30) can be used to construct an accurate estimator of the Doppler rate. Again, proposed…”

Section: B Frft Gainmentioning

confidence: 99%

“…The digital computation of the FRFT was published by Ozaktas et al [15]. The FRFT was a widely used tool in radar [16]- [20], image processing [21], [22], communications [23], [24], in which the signal is formed with linear frequency modulation (LFM), and it is still currently a powerful tool for different applications [25]- [28].…”

Section: Introductionmentioning

confidence: 99%

A Novel Doppler Rate Estimator Based on Fractional Fourier Transform for High-Dynamic GNSS Signal

Luo

Chen

et al. 2019

IEEE Access

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When the fractional Fourier transform (FRFT) is introduced into the weak and high-dynamic global navigation satellite system (GNSS) signal acquisition, the 2-D search cell will be transferred to a 3-D one with respect to the code chip, the Doppler shift, and the Doppler rate. The proper determinations of the code bin and Doppler shift bin in the acquisition process have already been covered in the previous researches. The aim of this paper is to provide an exhaustive analysis of the approach to specify an optimal FRFT order bin, in terms of the Doppler shift rate. The lower and upper bound of FRFT order ranges is determined by the incoming signal dynamics. Then, we propose a precise model to yield an optimal FRFT order bin. Besides, a novel and fast Doppler estimator based on the non-linear least square (NLS) method is presented to improve the performance of the digital FRFT implementation. Finally, an alternate search procedure is proposed to reduce the singular estimations of the NLS method. The simulating examples demonstrate the performance of the proposed algorithms. It has been verified that the computation efficiency and the estimation accuracy have been significantly improved by proposed techniques. INDEX TERMS Global navigation satellite system (GNSS) signal, linear frequency modulation (LFM), fractional Fourier transform (FRFT) order, acquisition, Doppler rate, non-linear least square (NLS).

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Embedding WFRFT Signals Into TDCS for Secure Communications

Cited by 12 publications

References 20 publications

Novel Modulation Recognition for WFRFT-Based System Using 4th-Order Cumulants

Novel Modulation Recognition for WFRFT-Based System Using 4th-Order Cumulants

M-Ary Cdma Scheme With CCSK Modulation and Parallel Interference Cancellation Technique

A Novel Doppler Rate Estimator Based on Fractional Fourier Transform for High-Dynamic GNSS Signal

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