Performance evaluation of low-earth-orbit (LEO) land mobile satellite channel using N-dimensional central moment technique (CMT)

Performance evaluation of a signal transmitted through a Low Earth Orbit (LEO) Land Mobile Satellite (LMS) channel involves a great degree of difficulty due to the system's complexity. It is particularly impossible to evaluate error performance in a direct manner using a closed form solution because of the fading effect and time-varying elevation angles (ELs) of the satellite.; Although modeling and verification of fading effects have been a long time subject of research in any mobile communication environment, there exists little information on the time-varying fading model for the LEO communication. To evaluate the system performance of the LEO system, techniques using computer simulation models based on the statistical analysis can provide a reasonable degree of accuracy. However, the process takes a great deal of time, especially when it is required to predict lower probability of bit error rate. Instead of the computer simulation, this research presents the mathematical formulation to calculate the error probability using numerical method.; In this dissertation, the LEO satellite channel is modeled by including most of the practical channel elements such as the nonlinearity of Traveling Wave Tube Amplifier (TWTA), fading effect, intersymbol interference (ISI), and adjacent channel interference (ACI) in addition to the conventional Additive White Gaussian Noise (AWGN) in up and down link. In this stage, focus is on the development and analysis of the time-varying fading model under different elevation angles (ELs) of the LEO satellite to derive an analytic form of error probability of the LEO satellite system. To evaluate this error probability function, numerical analysis method is employed by applying an N-dimensional central moment technique (CMT), where the discrete probability density functions of various degradation factors are constructed and used to evaluate probability of error. By using this method, the overall system performance of the LEO can be calculated in an effective manner.; Results of numerical analysis show that the system performance in the LEO environment is mainly affected by the different elevation angles of the LEO satellite. The system experiences great performance degradation when the LEO satellite is located at a low degree of elevation angle.