# Intelligent Beam-Hopping-Based Grant-Free Random Access in Secure IoT-Oriented Satellite Networks
## 1 Introduction
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Category** & **Grant-Based Access** & **Grant-Free Access** & **Conventional Packet Diversity/Segmentation Approach for Satellite Communication** \\ \hline \multirow{7}{*}{Advantage} & Reduces access collision by & & In DVB-RCS2, IoT devices which have low activity, limited energy resources, and short data packets can use the ALOHA protocol and its variants. IoT devices can randomly begin to access an RO (random access occasion) and frequency resources at the same time [31] \\  & Time–frequency resources are & & The lack of coordination leads to increased conflicts, challenges in blind data detection, difficulties in identifying activated devices, issues with channel estimation, and synchronization problems in the uplink [32; 33] \\ \hline \multirow{7}{*}{Limit} & A large number of accesses & & The lack of coordination leads to increased conflicts, challenges in blind data detection, difficulties in identifying activated devices, issues with channel estimation, and synchronization problems in the uplink [32; 33] \\  & & & \\ \cline{1-1}  & Adjusts access resources & & Collision resolution can be achieved with NOMA or \\ \cline{1-1}  & according to load and solves & & Enhanced Competitive \\ \cline{1-1}  & the continuous collision & & Resolution Diversity Slotted \\ \cline{1-1}  & problem after user collision & & \\ \cline{1-1}  & through user avoidance and & & \\ \cline{1-1}  & retransmission & & \\ \cline{1-1}  & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The advantages versus disadvantages of grant-based access and grant-free access. protocol is specifically designed to address the challenges of IoT-oriented satellite networks by enhancing access capacity, reducing latency, and ensuring high reliability. It achieves high access capacity by optimizing resource allocation and scheduling, allowing multiple IoT devices to connect and transmit data concurrently. To meet the low latency requirement, BH-GFRA employs a time-slot-based scheduling strategy, minimizing waiting times for devices, while prioritizing latency-sensitive data for faster transmission. Furthermore, high reliability is ensured through advanced channel estimation, error detection, and correction techniques, which mitigate the impact of signal attenuation and interference, ensuring robust data transmission even in challenging network conditions. In the proposed BH-GFRA, satellite and IoT devices access the network according to a time-sequenced beam-hopping pattern. This is achieved by transmitting their pre-allocated preamble to announce their activities. We also note that different types of terminals in the IoT initiate access at different times, so we reduce the impact of resource collisions between terminals by controlling the admission of different types of users in the time slots of the frequency-hopping pattern based on the constraints of the spatial and temporal distribution of users and satellites. The satellite transmits a data packet in the same slot as the beam-hopping pattern that is associated with the preamble. The probability of a collision in the frequency-hopping pattern is subjected to mathematical analysis, as is the capacity of the BH-GFRA protocol, to accommodate a specified maximum data transmission delay requirement. The remainder of the work is organized as follows: Section 2 presents the system model of this thesis and the procedure of the proposed beam-hopping-based grant-free random access; in Section 3, the resource-hopping mechanism is analyzed; Section 4 describes the performance metrics; Section 5 offers some simulation of this algorithm; and finally, Section 6 concludes this work.