Control System Analysis for Ground/Air-to-Air Laser Communications Using Simulation

Abstract

Laser communication using free-space optics is an important element of the proposed US Department of Defense (DoD) Transformational Communication System. It offers data rates on the order of several Gigabits per second, resists electromagnetic jamming and interference, and enjoys low probability of intercept and detection. This paper describes an investigation, carried out using a computer simulation, to analyze the performance of the laser beam steering control system consisting of two gimbals, a fast steering mirror, the global positioning system (GPS), and attitude sensors. Two different application scenarios were simulated: ground-to-air and air-to-air. The simulation evaluated several control system parameters such as pointing accuracy, tracking capabilities and bandwidth requirements. The results of the simulation elucidated the impact of the system bandwidth on the performance and functionality of the ground or air-to-air laser communication system. The results also showed close correlation between pointing and tracking error with the uncertainties of the system due to GPS and attitude sensor measurements.

Integrated topology control and routing in wireless optical mesh networks

“…We assume that a node can transmit to another node within its transmission range by aligning its transmitter with the other node's receiver. The steering of the optical beam can be performed in a variety of ways [43,32,11]. Coarse steering of the beams can be done using gimbals, and finer alignment can be done using Fast Steering Mirrors (FSMs), electro-optic devices or acousto-optic devices [43].…”

Short-Length Raptor Codes for Mobile Free-Space Optical Channels

“…For the ground-to-UAV system in Fig. 1, a practical tracking system has been developed which includes a gimbal for rotating the laser transmitter in two dimensions and GPS for UAV position information [3]. In this paper, we use the experimentally measured properties of this tracking system and include the effects of atmospheric scintillation [3], [11].…”

“…Define the plane X Y to be transverse to the optical axis. It is assumed, as in [3], that initial acquisition between UAV and base station has been completed before tracking. As in [3], the tracking process is performed periodically by updating the UAV position by GPS at a tracking interval T tr = 50 ms and orienting the gimbal accordingly.…”

“…Although most FSO links are stationary, they have also been considered for mobile applications. Applications such as ship-to-ship [2], ground-to-air and airto-air FSO communication systems have been studied [3], [4]. FSO links satisfy the needs of long-range deep-space communications [6] and have also been considered for military wireless communications [7].…”

“…1 where the speed of the UAV can reach several hundred meters per second [9]. In this scenario, tracking is typically accomplished by mechanical components such as a 2-dimensional rotating gimbal which is oriented based on fed back global positioning system (GPS) data from the UAV [3], [4]. Tracking is made more difficult due to the use of FSO transmitters with a small divergence angle to minimize geometric loss.…”