CubeSat Downlink Communications Enhanced by Movable Antennas

In this work, we propose to use the emerging movable antenna (MA) technology for enhancing the performance of a CubeSat downlink communication system. Specifically, one surface of the CubeSat is considered as the transmit region for antenna movement. Meanwhile, solar panels, which are deployed above the CubeSat body, are regarded as reflectors that lead to multi-path signals and may intensify channel gains. This phenomenon is exploited in this work to maximize the downlink channel gain by adjusting MA positions in the transmit region. The continuous orbital movement of the CubeSat alters the angle of departure (AoD) of each transmitted signal, which may potentially affect channel gains across numerous positions in the transmit region. Therefore, the maximum channel gain is achieved for different elevation angles of the CubeSat via moving the antenna across the entire transmit region. Numerical results confirm that the optimal position of the MA could be different for different CubeSat elevation angles. In addition, our examinations shows that the maximum average channel gain achieved by MA is higher by more than 3 dB compared to the fixed antenna case. This demonstrates that the emerging MA technology can significantly enhance the CubeSat communication performance (e.g., extending the communication coverage of the CubeSat), especially when the CubeSat is near the horizon relative to a ground receiver.