Many assumptions must be made when simulating a communication link, including the modulation format, channel coding, multiantenna transmission scheme, receiver processing, and channel modeling. In this episode, Emil Björnson and Erik G. Larsson are visited by Jakob Hoydis, Principal Research Scientist at NVIDIA, to discuss the fundamentals of linklevel simulations. Jakob has led the development of the new opensource simulator Sionna, which is particularly well suited for machine learning research. The conversation covers the needs and means for making accurate simulations, channel modeling, reproducibility, and how machine learning can be used to improve standard algorithms. Other topics that are discussed are MIMO decoding and technical debt. Sionna can be downloaded from https://nvlabs.github.io/sionna/ and the white paper that is mentioned in the episode is found here: https://arxiv.org/pdf/2203.11854.pdf Music: On the Verge by Joseph McDade. Visit Erik’s website https://liu.se/en/employee/erila39 and Emil’s website https://ebjornson.com/