https://jjcit.org/paper/290 10.5455/jjcit.71-1769912165 Nguyen Van Toan,Nguyen Ngoc Lan,Tran Trung Duy,Pham Ngoc Son,Nguyen Trung Hieu Hybrid satellite-terrestrial relay multicast networks,Fountain codes,Co-channel interference,Outage probability,Joint time and power allocation 8 2 1-Feb.-2026 2-Apr.-2026 and 29-Apr-2026 29-Apr.-2026 In this paper, we study outage performance of hybrid satellite-terrestrial relay multicast schemes employing Fountain codes. In the considered schemes, a satellite attempts to transmit its data to a group of ground users with the assistance of a terrestrial relay station. In the conventional scheme (referred to as ConV), the relay station forwards each Fountain packet to the ground users using decode-and-forward (DF). In the proposed scheme (referred to as ProP), the relay station stores Fountain packets received from the satellite and replaces the satellite in transmitting new Fountain packets to the ground users once it has collected a sufficient number of Fountain packets for data recovery. We derive exact closed-form expressions of outage probability (OP) at each user and system outage probability (SOP) for the ConV and ProP schemes, considering the impact of co-channel interference. Computer simulations are realized to validate the derived formulas. Moreover, a joint time and power allocation problem is formulated and solved to optimize the SOP performance for the two considered schemes.