# Design of an Integrated System for Spaceborne SAR Imaging and Data Transmission
###### Abstract  
In response to the conflicting demands between real-time satellite communication and high-resolution synthetic aperture radar (SAR) imaging, we propose a method that aligns the data transmission rate with the imaging data volume. This approach balances SAR performance with the requirements for real-time data transmission. To meet the need for mobile user terminals to access real-time SAR imagery data of their surroundings without depending on large traditional ground data transmission stations, we developed an application system based on filter bank multicarrier offset quadrature amplitude modulation (FBMC-OQAM). To address the interference problem with SAR signals' transmission and reception, we developed a signal sequence based on spaceborne SAR echo and data transmission and reception. This system enables SAR and data transmission signals to share the same frequency band, radio frequency transmission system, and antenna, creating an integrated sensing and communication system. Simulation experiments showed that, compared to the equal power allocation scheme for subcarriers, the echo image signal-to-noise ratio (SNR) improved by 2.79 dB and the data transmission rate increased by 24.075 Mbps. s 2024 24 6375 10.3390/s24196375 10.3390/s24196375 10.  
load, which is an X-band VOD communication payload for back-supportable application terminals [6]. Users in the satellite coverage areas would be able to control the SAR satellite in real time and to place mission instructions on the satellite. After the satellite completes remote sensing and graphics data in-orbit processing, it can transmit image data to users in real time, thus delivering an \"ordering, watching, and transmitting\" service. Given the commonality between the SAR satellite microwave payload and the VOD communication payload, the DFRC system can be used to reduce the number of single sets on the satellite, boost system integration and miniaturization, and improve spectrum utilization. The results verify the feasibility of the DFRC integrated system in space. Dual-functional radar and communication (DFRC) technology, which combines radar and communication functions into one, has significant potential for a variety of applications [7]. This technology allows a single system to perform detection and SAR tasks while also executing functions like communication, data transmission, and navigation simultaneously. DFRC systems enable the transmission of radar and communication signals using one device at the same time with the same frequency band. This integration reduces the need for extra communication payload equipment and eliminates the requirement for additional communication frequency allocations, enhancing the efficiency of electromagnetic spectrum utilization [8; 9]. The current DFRC research mainly focuses on studying joint modulation waveforms and radar application scenarios. [PERSON] et al. [10] suggested using continuous phase modulation and polyphase-coded frequency-modulated radar waveforms for transmitting information sequences. However, the efficiency of the communication signal is constrained by the radar's constant envelope waveform, limiting the amount of information that can be transmitted. [PERSON] et al. [11] and [PERSON] et al. [12] proposed a method using frequency division matrices for multi-input multi-output (MIMO) signals and adaptive MIMO signals. This approach utilizes a sidelobe modulation of communication signals to enable target tracking and communication functions within an integrated radar-communication system. However, the radar beams cannot cover all exploration areas simultaneously, leading to low energy efficiency. [PERSON] et al. [13] proposed using a chirp-based multicarrier frequency division waveform for efficient radar detection and communication on the same frequency band. However, the simultaneous use of radar and communication signals causes co-channel interference, requiring additional research on interference suppression methods. [PERSON] et al.