Implementation of a satellite channel simulator- 1- Implementation of a Real-Time Satellite Channel Simulator

This paper is focused upon implementation aspects of a real-time simulator applicable to narrowband land mobile satellite channels. The satellite channel is mainly affected by shadowing. If a direct signal component exists (line of sight (LOS) conditions), the channel is in a so-called good/clear state and the probability density function (pdf) of the signal amplitude is Rician distributed. The shadowed state (bad/blocked state) is modeled by a Rayleigh distribution of the signal amplitude whereat, with respect to the relative slow shadowing process, the mean power of the Rayleigh fading component is lognormal dis-tributed. The transitions between blocked and LOS periods modeled by a two state Markov chain. In order to regard the multipath propagation, the core software procedure of the simulator is a Rayleigh fading generator incorpo-rating a flexible (user definable) spectrum shaping to take into account Dop-pler effects due to mobility of the user and movements of the satellite. The real-time channel simulator is a useful tool to demonstrate the influence of the channel on mobile communication in laboratory or teaching purposes. In re-sponse to experimenters concerns, arbitrary RF-modules can be connected to the I/Q connectors of the simulator. The baseband channel simulator soft-ware runs on a high-performance TMS320C6701 DSP platform 1