Pointing error statistics

Optical wireless communication transceivers use in many cases very narrow laser beam divergence and very narrow field of view receiver telescope. The laser transmitter uses narrow laser beam divergence in order to minimize the transmitter power while the receiver uses very narrow field of view telescope in order to reduce background radiation noise [1-7]. As a result the pointing between the transmitter and the receiver is complicated and in order to establish optical communication between two transceivers, the line of sight of their optics must be aligned during the entire communication time. Optical acquisition and tracking system is used to keep line of sight of the transceivers. However, from time to time due to electronic noise, and mechanical vibration (e.g. wind in an urban system [2, 3] or jitter of antenna of a satellite [8, 9]) error in pointing direction occurs. In the following we present a simple model that describes the effect of the statistic of the pointing error on the performance of the communication system. We assume that the orthogonal direction of error pointing angle models are based on a normal distribution [1]. In that case the elevation pointing error angle is normally distributed with a probability density.