LTP Performance Evaluation Based on PHY Characteristics for Earth-Moon Satellite Links

As the growth in satellite applications and the Internet is projected to extend beyond Earth into the solar system, satellite networks operating beyond Earth's orbit are becoming a major point of interest. These satellite networks are expected to implement the Delay Tolerant Networking (DTN) architecture, which is specifically designed for networks with frequent intermittency, large delays, and high packet loss. The Licklider Transmission Protocol (LTP) is a specialized transport layer protocol used in space internetworking, providing reliability through retransmissions of the lost packets, with lower overhead compared to Transmission Control Protocol (TCP). This paper presents an analysis of LTP performance for satellite-to-satellite Earth-to-Moon links, based on the physical layer parameters of these radio links. Specifically, we defined the link budget for such links and, using two different modulation methods, calculated the segment error probability (SER). Given the SER, LTP performance was evaluated in terms of transmission time for varying block sizes. Our results show that a lower modulation order leads to a lower SER, which in turn reduces transmission time and increases throughput.