MIMO同频正交信号的构造及处理

同频正交波形即正交编码分集波形(orthogonal code division waveform , OCDW)由于各子阵发射载频相同,相对于正交频率分集波形(orthogonal frequency division waveform, OFDW)更适用于多输入多输出(multiple-input multiple-output, MIMO)雷达。而现有的同频正交序列的相关性能很差。为此,提出了一种同频正交相位编码信号的构造方法,通过使序列的互相关函数在单位元上周期性等间隔分布实现序列正交。进一步地,研究了多普勒频率对信号正交性的影响,分析了通道模糊现象和无模糊测速范围变窄现象,并根据回波特性给出了多普勒补偿以及距离多普勒(range-Doppler,RD)谱映射处理方法,以消除多普勒因素对处理结果的影响。仿真实验表明,该信号具有良好的正交性,给出的处理方法可消除多普勒对处理结果的影响。

Coding and processing of an orthogonal code division waveformset for MIMO radar system

The orthogonal code division waveform (OCDW) set, due to the same carries transmitted from each arrays, is more suitable for multiple-input multiple-output (MIMO) radar, compared with the orthogonal frequency division waveform (OFDW) set. However, the OCDW sets’ correlation property are far from being good. To address this, a method of coding orthogonal phase-code is proposed. This method achieves orthogonality by forcing the value of cross-correlation function cyclical located equidistantly on the unit circle. Further, the influence of Doppler frequency on the proposed waveform’s orthogonality is studied and the channel-ambiguity and narrowing of no-folding in Doppler domain are analyzed. To eliminate the undesired effect caused by Doppler shift, Doppler-compensation and range Doppler (RD) mapping are suggested, according to the characteristic of backscattered wave. Simulation results show that the proposed waveform set enjoys good orthogonality, and the proposed processing approach would eliminate the undesired effect caused by Doppler shift.