Study of Mobile Satellite Communications Employing PDMA with SIC

The number of terminals connected to the satellite network is expected to increase, influenced by the recent increase in communication requirements. Since the delay time cannot be ignored in links between geostationary orbit satellites and ground stations, a multiple access scheme that can accommodate many stations while minimizing retransmissions is required. In this paper, we propose a protocol for mobile satellite communications that aims to achieve low latency and high reliability by applying Successive Interference Cancellation (SIC) to Power Level Division Multiple Access (PDMA) using power and time domains. As one of the use cases, an urban model with traffic signals and buses as relay stations was assumed. First, we conducted a theoretical evaluation of communication quality and confirmed that PDMA achieves higher spectrum efficiency than conventional schemes. Then, we conducted simulations assuming the actual urban environment based on the Line of Sight duration and other factors to compare the performance of the proposed method with that of other multiple access schemes. The results showed that the proposed method reduced the delay by about 70% and reached higher throughput compared to the conventional scheme, even when using a lower level primary modulation scheme.