针对Chirp基调制信号在分数阶傅里叶变换域特征明显,信号周期易被检测等问题,提出一种能够实现多域隐蔽的低检测概率(low probability of detection,LPD)波形构造方法。该方法采用分数阶傅里叶变换跳频(fractional Fourier transform-fr...针对Chirp基调制信号在分数阶傅里叶变换域特征明显,信号周期易被检测等问题,提出一种能够实现多域隐蔽的低检测概率(low probability of detection,LPD)波形构造方法。该方法采用分数阶傅里叶变换跳频(fractional Fourier transform-frequency hopping,FrFT-FH)架构,在不改变Chirp信号扩频增益的前提下,通过时宽分割和重组(time width division and reorganization,TDR),降低信号在分数阶傅里叶变换域和周期域的能量聚敛特性。仿真结果表明,相较于现有LPD波形只能实现单一特征域隐蔽的问题,所提波形在不影响系统通信性能的前提下,面对频域检测、分数阶傅里叶变换域检测、周期域检测多种检测手段,在10 dB信噪比条件下的信号检测概率均低于0.2,满足系统在不同特征域下的LPD需求。展开更多
Recently,a weighted fractional Fourier transform(WFRFT)based hybrid carrier(HC)system has been proposed,which can converge single-carrier(SC)and multi-carrier(MC)systems.The cost and power dissipation of analog compon...Recently,a weighted fractional Fourier transform(WFRFT)based hybrid carrier(HC)system has been proposed,which can converge single-carrier(SC)and multi-carrier(MC)systems.The cost and power dissipation of analog components often dominate in practical HC systems.Therefore,in this paper,we analyze the baseband HC signal characteristics,including average signal power,power spectral density(PSD),probability density function(PDF),peak-to-average power ratio(PAPR),and complementary cumulative distribution function(CCDF),using a continuous-time HC signal approximation method.Through theoretical analysis and simulation validation,it is proved that the approximation method does not change the average signal power,bandwidth and out-of-band emission(OOBE).The theoretical PDF expression of HC signal with the approximation method is then proposed.Furt her more,the PDF can also explain why the PAPR of baseband continuous-time HC signal is higher than that of discrete-time HC signal.The PAPR performance and the power amplifier(PA)efficiency of HC systems in different conditions are analyzed.Through the PDF analysis of HC signal envelope and the numerical computations of PAPR.it is shown that the approximation method can offer a precise characteristic description for HC signal,which can help to improve the system PAPR performance and the PA efficiency.展开更多
文摘针对Chirp基调制信号在分数阶傅里叶变换域特征明显,信号周期易被检测等问题,提出一种能够实现多域隐蔽的低检测概率(low probability of detection,LPD)波形构造方法。该方法采用分数阶傅里叶变换跳频(fractional Fourier transform-frequency hopping,FrFT-FH)架构,在不改变Chirp信号扩频增益的前提下,通过时宽分割和重组(time width division and reorganization,TDR),降低信号在分数阶傅里叶变换域和周期域的能量聚敛特性。仿真结果表明,相较于现有LPD波形只能实现单一特征域隐蔽的问题,所提波形在不影响系统通信性能的前提下,面对频域检测、分数阶傅里叶变换域检测、周期域检测多种检测手段,在10 dB信噪比条件下的信号检测概率均低于0.2,满足系统在不同特征域下的LPD需求。
文摘以二进制正交键控(binary orthogonal keying,BOK)为传统方法调制Chirp信号的检测手段日益丰富,针对常用时频分析手段分数阶傅里叶变换和短时傅里叶变换对Chirp信号的高破译性问题,提出了一种将信息映射到Chirp信号时域的新型调制方式,即时变信息映射(time varying-information mapping,TVIM)调制,通过构建时域携带信息的调制模式,解决了周期能量聚敛特性,增加了以BOK为检测思想的信息干扰,加强了波形的低截获概率(low probability of intercept,LPI)。以数学推导和仿真分析的方法,探究了新型调制方式的误码特性、时频分析下LPI特性及先验信息抗破译性。理论分析和仿真验证表明,TVIM调制架构下,可保证比特信噪比在13 dB前误码率达到10-4,并提高了波形LPI性能。
基金the National Natural Science Foundation of China(No.61671179)the National Basic Research Program of China(No.2013CB329003)the Funding of Science and Technology on Communication Networks Laboratory。
文摘Recently,a weighted fractional Fourier transform(WFRFT)based hybrid carrier(HC)system has been proposed,which can converge single-carrier(SC)and multi-carrier(MC)systems.The cost and power dissipation of analog components often dominate in practical HC systems.Therefore,in this paper,we analyze the baseband HC signal characteristics,including average signal power,power spectral density(PSD),probability density function(PDF),peak-to-average power ratio(PAPR),and complementary cumulative distribution function(CCDF),using a continuous-time HC signal approximation method.Through theoretical analysis and simulation validation,it is proved that the approximation method does not change the average signal power,bandwidth and out-of-band emission(OOBE).The theoretical PDF expression of HC signal with the approximation method is then proposed.Furt her more,the PDF can also explain why the PAPR of baseband continuous-time HC signal is higher than that of discrete-time HC signal.The PAPR performance and the power amplifier(PA)efficiency of HC systems in different conditions are analyzed.Through the PDF analysis of HC signal envelope and the numerical computations of PAPR.it is shown that the approximation method can offer a precise characteristic description for HC signal,which can help to improve the system PAPR performance and the PA efficiency.
