Flexible Multiple Access Technology for Satellite Internet of Things
Access latency and complexity in the satellite Internet of Things(IoT)are significantly reduced by the grant-free uplink random access based on Slotted ALOHA(S-ALOHA).However,with the increase of the number of IoT users,the collision probability of S-ALOHA is markedly increased,thereby impacting the performance of the system.This paper addresses the scenario of massive device uplink access in satellite IoT,focusing on the investigation of power resource control for IoT terminals to achieve maximization of system rate.A flexible multiple access scheme based on S-ALOHA is proposed.In the presence of collisions in the system,transmission is carried out using non-orthogonal multiple access technology,which mitigates the issue of repeated transmission of user information and reduces transmission latency.The sequential decision problem of maximizing system rate under the constraint of terminal power is modeled as a Markov process,and the Advantage Actor-Critic(A2C)method is employed to solve it.The simulation results indicate that the success rate of terminal access in scenarios with a massive number of IoT terminals is effectively ensured by the proposed flexible multiple access technology.Additionally,the resource allocation algorithm based on A2C is shown to outperform traditional resource allocation algorithms.
Satellite Internet of Things(IoT)Flexible multiple accessResource allocationAdvantage Actor-Critic(A2C)