Adaptive Transmission Control Considering Available Channels Difference Among Terminals in Satellite IoT Systems Using CRDSA/IRSA

The use of Low Power Wide Area (LPWA) networks in the 920-MHz band, which are compatible with terrestrial network devices, is being explored for a satellite Internet-of-Things (IoT) system. In this system, terminals cannot use the channels the terrestrial networks use to avoid contention with them. Thus, terminals are limited to different channels depending on their location, resulting in throughput degradation. This study proposes an adaptive transmission control scheme to mitigate throughput degradation caused by different available channels for the Contention Resolution Diversity Slotted ALOHA (CRDSA)/Irregular Repetition Slotted ALOHA (IRSA). The proposed scheme reduces the estimation error of transmitting load at the base station, updates the transmission probability at the terminal to maximize the throughput by considering the characteristics of CRDSA/IRSA, and introduces smoothing of the transmission probability. This proposed scheme enables adaptive transmission control without the base station knowing the terminals’ available channels. We evaluated the proposed transmission control through simulation and clarified that it can achieve high throughput by preventing the influence of the available channel difference.