摘要
为利用同一信号同时实现雷达探测与通信传输,设计了一种恒包络OFDM雷达通信一体化信号。首先,对信号相位进行调制,将其分为通信调制项与雷达调制项;其次,设计通信调制项为OFDM相位乘以加权系数,并利用矢量合成的方法定量分析了其对雷达的影响,确定了通信加权系数的取值标准;然后,设计雷达调制项为一组余弦函数的和,并通过设置各余弦函数的调制系数,改变信号的模糊函数使雷达适用于不同场景;最后,利用三角函数的正交性及雷达波形确定性确立了解调步骤。仿真结果表明,当调制系数为随机序列时,能够得到图钉状模糊函数;在相同参数设置下,相比于传统恒包络OFDM信号,脉压后设计信号的第一旁瓣降低了25dB,主瓣宽度降低了7倍,利于实现雷达高分辨率、高检测概率探测,且随着序列长度增加,距离分辨率提高;通过控制通信加权系数的大小,可在雷达和通信性能之间取得最佳折中。
An extended constant envelope OFDM signal for an integrated radar and communi-cation system is proposed to perform radar detection and communication simultaneously. Phase modulations are performed to divide a phase into two parts, i.e., communication modulation and radar modulation. Communication modulation function is the real part of OFDM with a weighted coefficient. A vertical resultant theorem is introduced to quantitatively analyze the effect of embedded communication symbols on radar waveform performance and to ascertain the weighted coefficient of the communication modulation function. Radar modulation term is designed to be a sum of a series of cosine functions, and the modulation coefficient of each cosine function is set to change the ambiguity function shape of the signal and to make the radar suitable for different scenes. Orthogonality of trigonometric functions and certainty of radar waveforms are employed to establish the demodulation procedure. Simulation results show that a thumbtack-like ambiguity function is obtained by setting the modulation coefficient as a random sequence. The first side lobe of the designed signal is 25 dB lower than that of the original constant envelope OFDM signal, and the main lobe width is reduced by a factor of seven under the same setting parameters of a given context. Thus, high range resolution and Doppler resolution are achieved. The range resolution improves when the length of the random sequence increases. The best balance between radar performance and the communication bit error rate can be achieved through controlling the size of weighted coefficient of communication.
作者
张秋月
张林让
谷亚彬
周宇
ZHANG Qiuyue;ZHANG Linrang;GU Yabin;ZHOU Yu(National Laboratory of Radar Signal Processing,Xidian University,Xi’an 710071,China)
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
2019年第6期77-84,共8页
Journal of Xi'an Jiaotong University
基金
国家自然科学基金资助项目(61671361,61601343,61731023)
关键词
雷达通信一体化
OFDM信号
模糊函数
误码率
integration of radar and communication
OFDM signal
ambiguity function
bit error rate
