Outage Probability Analysis of Relay Communication Systems for Semantic Transmission

This paper focuses on relay semantic communication systems and deeply investigates their outage probability performance under different conditions. First, a three-point, two-link communication transmission model is constructed, which includes the source node, relay node, and destination node. The relay operates in half-duplex mode and is based on the DeepSC communication transmission model, with semantic and channel encoding/decoding implemented at both the source and relay nodes. Next, depending on the computational capabilities of the destination node, background knowledge, and channel conditions, the channel transmission strategies are classified into four scenarios: 1) Both the SR and RD links use semantic transmission, with the source and destination nodes having either the same or different background knowledge; 2) Both the SR and RD links use semantic transmission, but the signal is impaired, preventing the destination node from decoding; 3) The SR link uses semantic transmission, while the RD link performs bit transmission. For each scenario, the channel capacity formula and outage probability expressions are derived. In calculating the outage probability, the results are obtained by analyzing and deriving the distributions and conditions of relevant variables. Finally, Monte Carlo simulations are used to validate the theoretical analysis. The research results provide a theoretical basis for comprehensively understanding the performance of relay semantic communication systems and are of significant importance for advancing semantic communication technology.