Agile Beaconless Laser Beam Alignment with Adaptive Mm-Wave Beamforming for Inter CubeSat Communication

Inter small satellite/CubeSat communication (C2C) plays a key role in configuring mega low earth orbit satellite constellation. Highly directional laser links for C2C allows high-data-rate communication to enable massive data transmission with low delay and power consumption. However, the pointing loss from imperfect acquisition and tracking between satellites with different relative velocities prevent the optical links from achieving desired ultra-reliable link capacity. In this paper, we propose an agile beaconless laser beam alignment (ABLBA) method that requires less scanning time for pre-alignment between CubeSats. Mm-wave beamforming with uniform phased array (UPA) antennas is used to find the optimal half power beam width (HPBW) to guide the laser beam to achieve mutual alignment. Various HPBW with different transmitter configu-rations are considered for more power efficient and low delay C2C optical communication. The trade off between UPA antenna design and acquisition time is discussed. Based on studies of various parameter settings and corresponding laser beam width values, we conclude that ABLBA is capable of reducing the delay of laser beam pre-acquisition time in the presence of the CubeSat rigid body perturbation. Accuracy of mutual alignment is measured based on rating intersection surface in a geometric coverage model, which provides a direct mapping from the platform distance uncertainty to the performance of free space optical beam alignment.