This paper deals with the follower jamming(FJ)resistance for the frequency hopping(FH)communication system over additive white Gaussian noise(AWGN)channel.Conventional FH systems are susceptible to be jammed by FJ,and...This paper deals with the follower jamming(FJ)resistance for the frequency hopping(FH)communication system over additive white Gaussian noise(AWGN)channel.Conventional FH systems are susceptible to be jammed by FJ,and multi-pattern frequency hopping(MPFH)has good resistance to FJ.To further improve the FJ rejection capability of MPFH,we propose a wide gap multi-pattern frequency hopping(WGMPFH)scheme.WGMPFH uses channels to represent messages,and the data channel and complementary channel are hopping on orthogonal frequency slots according to wide gap FH patterns.The transmitted signal lures FJ to aim at the data channel and the complementary channel is away from FJ by adopting wide gap frequency patterns.FJ does not affect the complementary channel but increases the signal energy in the data channel,thus the effect of FJ is reduced.Its bit error rate(BER)is derived under FJ and the effects of three FJ parameters(tracking success probability,jamming duration ratio and jamming bandwidth ratio)on the BER performance of WGMPFH are investigated versus the co nventional FH/BFSK and MPFH system.Numerical and simulation results show that when under the worst-case FJ,the proposed WGMPFH outperforms the MPFH by about 1-3 dB and outperforms the conventional FH/BFSK by more than 4 dB.The proposed WGMPFH shows superior jamming rejection performance under FJ especially in severe signal-to-jamming ratio(SJR).展开更多
Coherent fast frequency hopping(CFFH)is attracting growing attention owing to its good antijamming performance and the coherent combining ability.However,compared with the conventional non-coherent fast frequency hopp...Coherent fast frequency hopping(CFFH)is attracting growing attention owing to its good antijamming performance and the coherent combining ability.However,compared with the conventional non-coherent fast frequency hopping,CFFH requires a more precise system synchronization.In this paper,we propose a new fine synchronization algorithm for CFFH.This algorithm consists two stages,namely,open-loop stage and closed-loop stage.In the openloop stage,a grid-based search parameter estimation method is proposed.In the closed-loop stage,we construct a fully coherent phase-locked loop(PLL)and a delay-locked loop(DLL)with decoding feedback structure to perform further fine estimation of the system clock skew and time delay,respectively.Moreover,we analyze the effect of the search parameter settings on the estimation error and derive the root mean squared error(RMSE)of estimates in the steady state of the closed-loop stage.Finally,through simulation,the RMSE performance are compared with the corresponding Cramer-Rao low bound(CRLB)and conventional code loop estimation to show the effectiveness of proposed algorithm.展开更多
We propose an encryption technique for underwater visible light communication[UVLC]based on chaotic phase scrambling[PS]and conjugate frequency hopping[CFH].The technique is experimentally tested using an 8-level puls...We propose an encryption technique for underwater visible light communication[UVLC]based on chaotic phase scrambling[PS]and conjugate frequency hopping[CFH].The technique is experimentally tested using an 8-level pulse amplitude modulation[PAM-8]and a 1.2 m underwater link.The security key of the phase scrambling code is generated according to a logistic map,and the frequency hopping is achieved by adding the same zero frequency points to the signal spectrum.The maximum transmission rate of 2.1 Gbit/s is measured with bit-error-rate[BER]below 7%the hard-decision forward error correction[HD-FEC]threshold of 3.8×10^(-3).展开更多
To improve the data rate of underwater acoustic frequency-hopped communications, frequency hopping is applied to different orders of fractional Fourier domain (FrFD), to enable non-intrusive, bandwidth-limited acousti...To improve the data rate of underwater acoustic frequency-hopped communications, frequency hopping is applied to different orders of fractional Fourier domain (FrFD), to enable non-intrusive, bandwidth-limited acoustic communications. An FrFD frequency-hopped communication method based on chirp modulation, namely multiple chirp shift keying-FrFD hopping (MCSK-FrFDH), is proposed for underwater acoustic channels. Validated by both simulations and experimental results, this method can reach a bandwidth efficiency twice more than conventional frequency-hopped methods with the same data rate and anti-multipath capability, suggesting that the proposed method achieves a better performance than the traditional frequency hopped communication in underwater acoustic communication channels. Results also show that in practical scenarios, the MCSK-FrFDH system with longer symbol length performs better at the low signal-to-noise ratio (SNR), while the system with larger frequency sweeping range performs better at a high SNR.展开更多
Attacking time-sensitive targets has rigid demands for the timeliness and reliability of information transmission, while typical Media Access Control（MAC） designed for this application works well only in very light-...Attacking time-sensitive targets has rigid demands for the timeliness and reliability of information transmission, while typical Media Access Control（MAC） designed for this application works well only in very light-load scenarios; as a consequence, the performances of system throughput and channel utilization are degraded. For this problem, a feedback-retransmission based asynchronous FRequency hopping Media Access（FRMA） control protocol is proposed. Burst communication, asynchronous Frequency Hopping（FH）, channel coding, and feedback retransmission are utilized in FRMA. With the mechanism of asynchronous FH, immediate packet transmission and multi-packet reception can be realized, and thus the timeliness is improved.Furthermore, reliability can be achieved via channel coding and feedback retransmission. With theories of queuing theory, Markov model, packets collision model, and discrete Laplace transformation, the formulas of packet success probability, system throughput, average packet end-to-end delay, and delay distribution are obtained. The approximation accuracy of theoretical derivation is verified by experimental results. Within a light-load network, the proposed FRMA has the ability of millisecond delay and 99% reliability as well as outperforms the non-feedback-retransmission based asynchronous frequency hopping media access control protocol.展开更多
By using d-form function, a new construction of frequency hopping sequence with optimal Hamming correlation is presented in this article, which generalizes the results presented by Ding （2007）. Furthermore, a new cl...By using d-form function, a new construction of frequency hopping sequence with optimal Hamming correlation is presented in this article, which generalizes the results presented by Ding （2007）. Furthermore, a new class of non-power function style d-form function is proposed and an upper bound of the Hamming autocorrelation of the corresponding sequence is also derived.展开更多
Many properties of frequency-hopped spread-spectrum multiple access （FH/SSMA）, such as, robustness against frequency selective fading and jamming make it a preferred multiple access communication scheme. But cochann...Many properties of frequency-hopped spread-spectrum multiple access （FH/SSMA）, such as, robustness against frequency selective fading and jamming make it a preferred multiple access communication scheme. But cochannel interference （CCI） can seriously harm the system＇s performance. On the basis of the analysis of the CCI pattern of frequency hopped multiple access signal, a new multiuser detection algorithm for canceling the CCI in frequency hopped multiple access systems is proposed. In the proposed scheme, the CCI is canceled by first detecting the frequency hopping slot, and then classifying and regenerating the candidates of the interference pattern from the time-frequency matrix. Both the theoretical analysis and computer simulation results show that compared to the conventional detector and Mabuchi＇s detector, this new multiuser detector has lower complexity, better convergence stability, and is suitable for both additive white Gaussian noise （AWGN） channels and Rayleigh fading channels.展开更多
基金The National Natural Science Foundation of China(No.61531009,No.61471108)The National Major Projects of China(No.2016ZX03001009)。
文摘This paper deals with the follower jamming(FJ)resistance for the frequency hopping(FH)communication system over additive white Gaussian noise(AWGN)channel.Conventional FH systems are susceptible to be jammed by FJ,and multi-pattern frequency hopping(MPFH)has good resistance to FJ.To further improve the FJ rejection capability of MPFH,we propose a wide gap multi-pattern frequency hopping(WGMPFH)scheme.WGMPFH uses channels to represent messages,and the data channel and complementary channel are hopping on orthogonal frequency slots according to wide gap FH patterns.The transmitted signal lures FJ to aim at the data channel and the complementary channel is away from FJ by adopting wide gap frequency patterns.FJ does not affect the complementary channel but increases the signal energy in the data channel,thus the effect of FJ is reduced.Its bit error rate(BER)is derived under FJ and the effects of three FJ parameters(tracking success probability,jamming duration ratio and jamming bandwidth ratio)on the BER performance of WGMPFH are investigated versus the co nventional FH/BFSK and MPFH system.Numerical and simulation results show that when under the worst-case FJ,the proposed WGMPFH outperforms the MPFH by about 1-3 dB and outperforms the conventional FH/BFSK by more than 4 dB.The proposed WGMPFH shows superior jamming rejection performance under FJ especially in severe signal-to-jamming ratio(SJR).
基金funded by National Scientific Foundation of China under grants(No.62101050 and No.62001022).
文摘Coherent fast frequency hopping(CFFH)is attracting growing attention owing to its good antijamming performance and the coherent combining ability.However,compared with the conventional non-coherent fast frequency hopping,CFFH requires a more precise system synchronization.In this paper,we propose a new fine synchronization algorithm for CFFH.This algorithm consists two stages,namely,open-loop stage and closed-loop stage.In the openloop stage,a grid-based search parameter estimation method is proposed.In the closed-loop stage,we construct a fully coherent phase-locked loop(PLL)and a delay-locked loop(DLL)with decoding feedback structure to perform further fine estimation of the system clock skew and time delay,respectively.Moreover,we analyze the effect of the search parameter settings on the estimation error and derive the root mean squared error(RMSE)of estimates in the steady state of the closed-loop stage.Finally,through simulation,the RMSE performance are compared with the corresponding Cramer-Rao low bound(CRLB)and conventional code loop estimation to show the effectiveness of proposed algorithm.
基金supported by the National Key Research and Development Program of China(No.2022YFB2802803)the National Natural Science Foundation of China(Nos.61925104,62031011,and 62201157)the Major Key Project of PCL。
文摘We propose an encryption technique for underwater visible light communication[UVLC]based on chaotic phase scrambling[PS]and conjugate frequency hopping[CFH].The technique is experimentally tested using an 8-level pulse amplitude modulation[PAM-8]and a 1.2 m underwater link.The security key of the phase scrambling code is generated according to a logistic map,and the frequency hopping is achieved by adding the same zero frequency points to the signal spectrum.The maximum transmission rate of 2.1 Gbit/s is measured with bit-error-rate[BER]below 7%the hard-decision forward error correction[HD-FEC]threshold of 3.8×10^(-3).
基金supported by the National Natural Science Foundation of China(4137604041676024)
文摘To improve the data rate of underwater acoustic frequency-hopped communications, frequency hopping is applied to different orders of fractional Fourier domain (FrFD), to enable non-intrusive, bandwidth-limited acoustic communications. An FrFD frequency-hopped communication method based on chirp modulation, namely multiple chirp shift keying-FrFD hopping (MCSK-FrFDH), is proposed for underwater acoustic channels. Validated by both simulations and experimental results, this method can reach a bandwidth efficiency twice more than conventional frequency-hopped methods with the same data rate and anti-multipath capability, suggesting that the proposed method achieves a better performance than the traditional frequency hopped communication in underwater acoustic communication channels. Results also show that in practical scenarios, the MCSK-FrFDH system with longer symbol length performs better at the low signal-to-noise ratio (SNR), while the system with larger frequency sweeping range performs better at a high SNR.
基金supported by the National Natural Science Foundation of China(No.61501496)
文摘Attacking time-sensitive targets has rigid demands for the timeliness and reliability of information transmission, while typical Media Access Control（MAC） designed for this application works well only in very light-load scenarios; as a consequence, the performances of system throughput and channel utilization are degraded. For this problem, a feedback-retransmission based asynchronous FRequency hopping Media Access（FRMA） control protocol is proposed. Burst communication, asynchronous Frequency Hopping（FH）, channel coding, and feedback retransmission are utilized in FRMA. With the mechanism of asynchronous FH, immediate packet transmission and multi-packet reception can be realized, and thus the timeliness is improved.Furthermore, reliability can be achieved via channel coding and feedback retransmission. With theories of queuing theory, Markov model, packets collision model, and discrete Laplace transformation, the formulas of packet success probability, system throughput, average packet end-to-end delay, and delay distribution are obtained. The approximation accuracy of theoretical derivation is verified by experimental results. Within a light-load network, the proposed FRMA has the ability of millisecond delay and 99% reliability as well as outperforms the non-feedback-retransmission based asynchronous frequency hopping media access control protocol.
基金supported by the Key Project of Fujian Provincial Universities-Information Technology Research Based on Mathematics,Natural Science Foundation of Fujian Province (2010J01319)the Excellent Young Teacher Developing Program of Fujian Normal University (2008100211)
文摘By using d-form function, a new construction of frequency hopping sequence with optimal Hamming correlation is presented in this article, which generalizes the results presented by Ding （2007）. Furthermore, a new class of non-power function style d-form function is proposed and an upper bound of the Hamming autocorrelation of the corresponding sequence is also derived.
基金the National Natural Science Foundation of China (60372055)National Doctoral Foundation of China (20030698027).
文摘Many properties of frequency-hopped spread-spectrum multiple access （FH/SSMA）, such as, robustness against frequency selective fading and jamming make it a preferred multiple access communication scheme. But cochannel interference （CCI） can seriously harm the system＇s performance. On the basis of the analysis of the CCI pattern of frequency hopped multiple access signal, a new multiuser detection algorithm for canceling the CCI in frequency hopped multiple access systems is proposed. In the proposed scheme, the CCI is canceled by first detecting the frequency hopping slot, and then classifying and regenerating the candidates of the interference pattern from the time-frequency matrix. Both the theoretical analysis and computer simulation results show that compared to the conventional detector and Mabuchi＇s detector, this new multiuser detector has lower complexity, better convergence stability, and is suitable for both additive white Gaussian noise （AWGN） channels and Rayleigh fading channels.
