OFDM SAR成像方法综述

张天贤; 夏香根

doi:10.12000/JR19116

OFDM SAR成像方法综述

DOI: 10.12000/JR19116

张天贤^1, ,,
夏香根^2, ,

1.
电子科技大学信息与通信工程学院成都 611731
2.
美国特拉华大学电子与计算机工程系纽瓦克市 DE 19716

基金项目: 国家自然科学基金 (61971109)，中央高校基本业务费 (2672018ZYGX2018J009)

详细信息

作者简介:
张天贤(1985–)，男，广东云浮人，博士，电子科技大学副教授，硕士生导师。主要研究方向包括：博弈进化、多功能一体资源管控、任务规划、多功能波形设计等。E-mail: txzhang@uestc.edu.cn

夏香根(1963–)，男，江苏高淳人，美国特拉华大学教授，IEEE Fellow，曾担任过IEEE Trans. SP, IEEE Trans. WC, IEEE Trans. MC和IEEE Trans. VT等国际期刊副主编。主要研究方向包括：无线通信和雷达信号处理。E-mail: xxia@ee.udel.edu

通讯作者:
张天贤 txzhang@uestc.edu.cn

夏香根 xxia@ee.udel.edu

责任主编：梁兴东 Corresponding Editor: LIANG Xingdong
中图分类号: TN958
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出版历程
- 收稿日期: 2019-12-22
- 修回日期: 2020-04-22
- 网络出版日期: 2020-04-01

An Overview of OFDM SAR Imaging Methods

ZHANG Tianxian^{1
, ,},
XIA Xiang-Gen^{2
, ,}

1.
School of Information and Communication Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China
2.
Department of Electrical and Computer Engineering, University of Delaware, Newark DE 19716, USA

Funds: The National Natural Science Foundation of China (61971109), The Fundamental Research Funds for the Central Universities (2672018ZYGX2018J009)

More Information

Corresponding author: ZHANG Tianxian, txzhang@uestc.edu.cn; XIA Xiang-Gen, xxia@ee.udel.edu

摘要

摘要: 近年来，正交频分复用(OFDM)信号由于具有正交性以及大带宽特性被广泛应用于合成孔径成像(SAR)研究中。相比传统SAR成像，由于其信号的独特性，OFDM SAR在成像上具有一定优势，但也面临着很多挑战。该文根据天线配置的不同，分别对单天线OFDM SAR成像和多天线MIMO OFDM SAR成像所面临的问题进行了梳理与总结，重点讨论了基于OFDM信号和基于循环前缀(CP)OFDM信号的SAR/MIMO SAR成像方法，并分析了OFDM SAR未来的可能发展方向。
- 正交频分复用 /
- 合成孔径成像 /
- 循环前缀-正交频分复用
Abstract: In recent years, Orthogonal Frequency Division Multiplexing (OFDM) signal has been widely used in Synthetic Aperture Radar (SAR) imaging research due to its orthogonality and large bandwidth. Compared with the traditional SAR, OFDM SAR has certain advantages in imaging applications because of its unique signal characteristics. Nevertheless, OFDM SAR faces many challenges. In this paper, on the basis of different antenna configurations, the problems and studies of single-antenna OFDM SAR imaging and multi-antenna MIMO OFDM SAR imaging are reviewed. The imaging methods of SAR/MIMO SAR based on OFDM and cyclic prefix OFDM signals are discussed, and some possible future research directions of OFDM SAR are presented.
- Orthogonal frequency division multiplexing (OFDM) /
- Synthetic aperture imaging /
- CP-OFDM

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图 1 单站正侧视条带SAR几何关系图

Figure 1. Monostatic stripmap SAR geometric diagram

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图 2 传统SAR成像流程图

Figure 2. Traditional SAR imaging flow chart

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图 3 雷达距离向分辨单元分割示意图

Figure 3. Illustration diagram of a range line

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图 4 归一化目标距离向点扩展函数

Figure 4. Normalized range profiles of a point spread function

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图 5 坦克形状目标的SAR成像结果

Figure 5. Imaging results of simulated reflectivity profile for a tank

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图 6 MIMO SAR示意图

Figure 6. MIMO SAR sketch map

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图 7 算法实现框图^[51]

Figure 7. Algorithm implementation block diagram^[51]

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图 8 不同发射-接收对距离像恢复效果

Figure 8. Range reconstruction results of target for different transmitter and receiver pairs

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表 1 OFDM SAR和CP-OFDM SAR成像的研究重点

Table 1. Research focus of OFDM SAR and CP-OFDM SAR

	研究重点	技术细节
OFDM SAR 成像方法	干扰与杂波抑制方法	利用混沌编码的信号优化设计实现干扰抑制；通过频域编码，增加频率多样性，改善强杂波环境下的成像效果。
	多普勒频移处理方法	采用多普勒补偿技术缓解频移对OFDM SAR成像的影响；采用低多普勒敏感信号(FBMC)，抑制频移的影响。
	距离模糊抑制方法	利用遗传算法优化设计发射信号实现距离模糊抑制；发射子脉冲独立编码、独立匹配滤波，实现子条带无模糊且高分辨，通过子条带拼接实现无模糊宽幅成像。
	相位历程提取方法	采用最小二乘估计(LSE)和MUSIC-LSE的方法提取相位历程，提高单/多目标方位向成像的抗干扰和抗噪声性能。
CP-OFDM SAR 成像方法	不采用SAR成像中的传统匹配滤波算法，而是通过引入CP来实现IRCI-free距离像重构，大大改善传统匹配滤波算法的高旁瓣问题。

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表 2 MIMO OFDM SAR和MIMO CP-OFDM SAR成像的研究重点

Table 2. Research focus of MIMO OFDM SAR and MIMO CP-OFDM SAR

	研究重点	技术细节
MIMO OFDM 成像研究	OFDM-LFM正交发射波形设计	基于交错正交频分复用(I-OFDM)原理结合LFM对信号进行优化设计，实现恒模、大且稳定的发射功率，研究其在MIMO SAR中调制解调以及成像方法；基于OFDM-LFM信号，结合空时编码相关理论，保证子阵列间的相互正交，通过匹配滤波及多波束形成算法实现宽测绘带与高分辨成像。
MIMO OFDM 成像研究	OFDM正交发射波形设计	提出随机子载波正交信号集设计方法，通过优化设计得到子载波的频谱分布结构和加权方案，保证发射端各通道具有较低相关性，改善峰值模糊等问题。
MIMO CP-OFDM 成像研究	MIMO CP-OFDM雷达是在共享频谱的情况下，实现不同天线发射信号在离散频域里的正交性，提出脉冲压缩和脉冲相干积累协同方法，理论上可消除不同发射信号的同频串扰，消除距离旁瓣串扰，且达到多天线的空间分集。

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