The continuous development of cellular communication technology has come to the fifth-generation (5G). In Indonesia, 5G is predicted to be officially launched and operated in 2025. To make it possible, the government already has a 5G-spectrum outlook; 3.5 GHz (3.3 - 4.2 GHz), 15 GHz (14.5 - 15.35 GHz), 26 GHZ (24.25 - 27.5 GHz), and 28 GHz (26.5 - 29.5 GHz). Unfortunately, these frequencies have already been filled in or have an existing spectrum, respectively. As a result, one way to overcome is by a co-channel frequency between 5G and the existing frequency, such as 27.5 - 28.5 GHz, which is dedicated for Fixed Satellite Service (FSS) services. The developed technology by the government is High Throughput Satellite (HTS). HTS is a satellite with a higher throughput level than conventional satellite services, and HTS can work on C, Ku, and Ka-Band bands. With the government's development of 5G and HTS simultaneously, mitigation is required so that it does not cause interference if the frequency co-channel occurs. The simulation has been done for co-channel 28 GHz between HTS and 5G by SPECTRAemc. Hence, the mitigation is proposed to be used for both services.