Transmission Control Considering Different Available Channels for CRDSA/IRSA in Satellite IoT Systems

In satellite Internet-of-Things (IoT) systems using the 920-MHz band Low Power Wide Area, available channels for each terminal are limited to avoid interference with terrestrial networks. Since this limitation depends on the location of the terminal, the available channels are different, resulting in throughput degradation. This paper proposes a transmission control scheme that reduces throughput degradation due to different available channels in the Contention Resolution Diversity Slotted ALOHA (CRDSA)/Irregular-Repetition Slotted ALOHA (IRSA) system. The proposed transmission control uses constraints that consider the characteristics of CRDSA/IRSA, as well as an objective function that considers fairness of throughput among terminals. Under these constraints and objective function, the transmission probability was calculated using an objective function that maximized the transmitting load. The computer simulation showed that it could achieve high throughput by preventing the influence of difference in the available channels.