Integrated Terrestrial-Wired and LEO Satellite With Offline Bidirectional Cooperation for 6G IoT Networks

This article presents a novel framework for integrating low-Earth orbit satellites (LEOSs) with terrestrial-wired networks to improve coverage, throughput, and transmission reliability of sixth generation (6G) Internet of Things (IoT) networks. The proposed framework utilizes the synergy of nonorthogonal multiple access (NOMA), automatic repeat request (ARQ), and cooperative communications to maximize the data downloaded from a LEOS to multiple terrestrial users. More specifically, we propose a novel offline packets repair and recovery (PRR) technique to reduce the number of dropped packets, where the wired-terrestrial connection is used to enable efficient bidirectional cooperation, to improve the reliability of the received data by reducing the multiuser interference inherent to NOMA. Moreover, by exchanging the acknowledgment messages used with ARQ, efficient chase combining (CC) is applied to improve the signal to noise ratio (SNR) of the received packets. Extensive Monte Carlo simulation experiments are used to evaluate and quantify the advantages of the proposed system. The results obtained show that the proposed system can repair a significant number of dropped packets, which reduces the packet drop rate and improves the network throughput. In several scenarios, the proposed PRR managed to repair and recover more than 90% of the dropped packets.