In this paper, a digital transmission scheme protected by a packet-level forward error correction (FEC) coding technique is proposed for optical feeder links in a satellite communication system. The architectures of the gateway and the satellite are defined, including the building blocks of the interface between the radio frequency (RF) front-end and the optical front-end, as well as the digital signal processor. The system is designed to cater for Terabit/s high-throughput satellite (HTS) applications. In addition, the turbulent atmospheric optical channel is modeled for different elevation setups and optical ground station (OGS) altitudes in untracked and tracked beam scenarios. The performance of the digital transmission scheme is evaluated in the forward and return link channels. It is shown that fade mitigation techniques such as packet-level FEC coding in the forward link, as well as beam tracking, and large-aperture OGS telescope in the return link are essential to close the link budget of a Terabit/s satellite transmission link.