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
The chaotic frequency hopping (FH) communication systems have been presented so far. The chaotic sequences possesses good randomness and sensitive dependence on initial conditions, which is quite advantageous to run t...The chaotic frequency hopping (FH) communication systems have been presented so far. The chaotic sequences possesses good randomness and sensitive dependence on initial conditions, which is quite advantageous to run the FH codes in code-division multiple access (CDMA) systems. But the finite precision of computation and the fact of the low-dimensional chaos predicted easily cause difficulty in chaotic application. In this paper, some disadvantages associated with the conventional FH codes and the chaotic code scrambled by m-sequences are reviewed briefly. In order to overcome these drawbacks to some extents, a new higher performance FH code called cipher quasi-chaotic (CQC) code is proposed, which is generated by combining the clock-controlled stream cipher technique and chaotic dynamics. Performance analysis applying in FH communication systems of this kind of code is given. The privacy of the CQC sequence is also analyzed.展开更多
In this paper, we investigate the issues of initialization and deployment of wireless sensor networks（WSNs） under IEEE 802.11 b/g interference and fading channels using frequency hopping（FH）. We propose an FH algo...In this paper, we investigate the issues of initialization and deployment of wireless sensor networks（WSNs） under IEEE 802.11 b/g interference and fading channels using frequency hopping（FH）. We propose an FH algorithm for WSNs, which is implemented and tested with a pair of nodes employing IPv6 over low power wireless personal area networks（6 LoWPAN） standard.The merits and demerits of the proposed FH scheme in WSNs are studied under strong IEEE 802.11 b/g interference and frequency selective fading channels. We compare the performance results of the proposed FH scheme with those obtained by single-channel radio in WSNs, and show that FH maintains very reliable data rates in the presence of adverse conditions where the single-channel radio fails. We determine a minimum center frequency offset of channels between IEEE 802.15.4 and IEEE 802.11 b/g-based networks, which guarantees the error free network operation of IEEE802.15.4 using a single channel. We design a second FH procedure comprising only four free channels（15, 20, 25, and 26） of IEEE 802.15.4 standard, and show that in the presence of nearby IEEE 802.11 b/g interference, the IEEE 802.15.4 data rate using this method is always 98% and more.展开更多
针对传统跳频网台分选技术在低信噪比条件下检测效果不佳且实时性差的问题,本文提出一种基于YOLOv8(You Only Look Once version 8)的跳频信号分选算法.首先,对接收到的混叠信号进行短时傅里叶变换生成灰度时频图作为YOLOv8网络模型的输...针对传统跳频网台分选技术在低信噪比条件下检测效果不佳且实时性差的问题,本文提出一种基于YOLOv8(You Only Look Once version 8)的跳频信号分选算法.首先,对接收到的混叠信号进行短时傅里叶变换生成灰度时频图作为YOLOv8网络模型的输入.其次,针对混叠信号中扫频、定频信号以及跳频信号之间发生频率碰撞对检测精度的影响,在C2f层中引入可变形卷积核(Deformable Convolutional Net-works v2,DCNv2)提高网络特征提取的泛化能力.再次,在Backbone层中加入SimAM注意力机制,解决低信噪比下背景噪声易与跳频信号混淆影响检测精度的问题.最后,将Detect检测头的卷积核替换为局部卷积核(Partial Convolution,PConv),在mAP@0.5精度损失不超过0.37%的情况下使网络计算复杂度降低32.18%,提高网络模型的推理速度.实验结果表明,本文所提算法在信噪比为-5 dB时分选率达到97.68%,且模型收敛快,鲁棒性强.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
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This project was supported by the National High Technology Research and Development Program of China (2002AA144110)the National Natural Science Foundation of China (60272082) the Postdoctoral Science Foundation of China(2003033304).
文摘The chaotic frequency hopping (FH) communication systems have been presented so far. The chaotic sequences possesses good randomness and sensitive dependence on initial conditions, which is quite advantageous to run the FH codes in code-division multiple access (CDMA) systems. But the finite precision of computation and the fact of the low-dimensional chaos predicted easily cause difficulty in chaotic application. In this paper, some disadvantages associated with the conventional FH codes and the chaotic code scrambled by m-sequences are reviewed briefly. In order to overcome these drawbacks to some extents, a new higher performance FH code called cipher quasi-chaotic (CQC) code is proposed, which is generated by combining the clock-controlled stream cipher technique and chaotic dynamics. Performance analysis applying in FH communication systems of this kind of code is given. The privacy of the CQC sequence is also analyzed.
基金supported by the Important National Science and Technology Specific Project of China(2018ZX03001020-0052016ZX03001022-006)+2 种基金the National Natural Science Foundation of China(61771308)the Shanghai Science and Technology Committee(16DZ1100402)the Special Project of Military and Civilian Integration of Shanghai Economic and Information Committee with the name"Ultra High Sensitivity UAV Communication System Based on Radar Related Technology"
文摘In this paper, we investigate the issues of initialization and deployment of wireless sensor networks（WSNs） under IEEE 802.11 b/g interference and fading channels using frequency hopping（FH）. We propose an FH algorithm for WSNs, which is implemented and tested with a pair of nodes employing IPv6 over low power wireless personal area networks（6 LoWPAN） standard.The merits and demerits of the proposed FH scheme in WSNs are studied under strong IEEE 802.11 b/g interference and frequency selective fading channels. We compare the performance results of the proposed FH scheme with those obtained by single-channel radio in WSNs, and show that FH maintains very reliable data rates in the presence of adverse conditions where the single-channel radio fails. We determine a minimum center frequency offset of channels between IEEE 802.15.4 and IEEE 802.11 b/g-based networks, which guarantees the error free network operation of IEEE802.15.4 using a single channel. We design a second FH procedure comprising only four free channels（15, 20, 25, and 26） of IEEE 802.15.4 standard, and show that in the presence of nearby IEEE 802.11 b/g interference, the IEEE 802.15.4 data rate using this method is always 98% and more.
文摘针对传统跳频网台分选技术在低信噪比条件下检测效果不佳且实时性差的问题,本文提出一种基于YOLOv8(You Only Look Once version 8)的跳频信号分选算法.首先,对接收到的混叠信号进行短时傅里叶变换生成灰度时频图作为YOLOv8网络模型的输入.其次,针对混叠信号中扫频、定频信号以及跳频信号之间发生频率碰撞对检测精度的影响,在C2f层中引入可变形卷积核(Deformable Convolutional Net-works v2,DCNv2)提高网络特征提取的泛化能力.再次,在Backbone层中加入SimAM注意力机制,解决低信噪比下背景噪声易与跳频信号混淆影响检测精度的问题.最后,将Detect检测头的卷积核替换为局部卷积核(Partial Convolution,PConv),在mAP@0.5精度损失不超过0.37%的情况下使网络计算复杂度降低32.18%,提高网络模型的推理速度.实验结果表明,本文所提算法在信噪比为-5 dB时分选率达到97.68%,且模型收敛快,鲁棒性强.
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.
