Joint Access Control and Pilot Design to Minimize Average AoI in Cell-Free Massive MIMO System With Grant-Free Random Access

As one of the most critical tasks currently, it is essential to excavate the status update performance. In this article, we combine access control and pilot design to minimize average Age of Information (AoI) in cell-free (CF) massive multiple–input multiple-output (MIMO) system with grant-free (GF) random access, where the positions of both the access points (APs) and machine-type communication devices (MTCDs) are geographically distributed as independent Poisson point processes (PPPs). Based on the establish two-disk computation model, we first formulate the access successful probability by leveraging the stochastic geometry for GF transmission. Then, the closed-form expression of the average AoI is approximately derived. The derived results enable us precisely quantify the impact of network parameters on the system-level performance. To minimize the average AoI, a joint access control and pilot design scheme is proposed. Finally, simulation results are provided to furnish invaluable insight into system performance and certificate the validity of the proposed algorithm.