Signal constellation design for intensity modulated free-space optical communications

Free-space optical (FSO) communications is a promising candidate for future high-speed wireless communications. Signal constellation design is an important problem for all kinds of communications. In this paper, we try to design the signal constellation for the intensity modulated FSO communications. A channel model is first established, which includes atmospheric loss, atmospheric turbulence and pointing error. Under the constraints of non-negativity, peak power and average power, a signal space is obtained. Then, a distance measure based on the non-coherent maximum likelihood detection is introduced. By maximizing the minimum distance, the signal constellation optimization problem is formulated. After that, an interior point method based algorithm is given to solve the optimization problem. Simulation results are presented to show the derived signal constellation.