Operating Point Sensitivity Study to Turbo Coded Satellite Communication Systems

The availability of spectrum at Ka-Band frequencies has become a compelling reason for communication satellite operators to develop systems using Ka-band links. A disadvantage is that the required transmit power must overcome significant propagation loss at Ka-band frequencies. Forward error correcting (FEC) codes with channel interleaving are essential to higher data rate satellite communication applications, where coding gain is necessary to achieve the desired link performance with limited transmit power. FEC codes selection is a critical decision in satellite communication system design. In this paper, we develop a methodology for evaluating code performance sensitivity to downlink transmit power variation. A typical space-to-ground link budget derives the required effective isotropic radiating power (EIRP) under the constraints of current high power amplifier and antenna technology. serial and parallel turbo codes are chosen for the analysis. The trade-offs for performance sensitivity are decoder implementation complexity and decoder power consumption. Simulated performance results are incorporated in the link analysis. A summary of the relative FEC codes sensitivities to energy-per-bit to noise-density ratio (E_b/N_o) variation is provided. From the performance comparison, we have characterized the satellite link operating point sensitivity