Improving the Timeliness of Two-Source Status Update Systems in Internet of Vehicles With Source-Dedicated Buffer: Resource Allocation

Abstract

Age of information (AoI) is a pertinent metric for characterizing the timeliness of status updates in Internet of Vehicles (IoV). Resources allocated to update transmission would significantly affect the timeliness of status update observed at the receiver end. This work investigates the sum average AoI of a two-source wireless updating system in IoV by modeling the system as a non-preemptive queue with a size-two source-dedicated buffer. Two bandwidth allocation schemes, i.e., an asynchronous time division multiplexing (ATDM) scheme and a dynamic bandwidth allocation (DBA) scheme, are proposed for the system. In the ATDM scheme, status updates are transmitted using all available bandwidth sequentially while in the DBA scheme, the server fractionally allocates the available bandwidth for transmitting the arrived update based on the buffer state. By analyzing the age evolution of each update stream based on stochastic hybrid systems, the closed-form per-source average AoI and the sum average AoI of the two proposed schemes are derived. In particular, the per-source average AoI when the system provides priority for serving one update stream is also given. It is demonstrated that by employing the ATDM scheme and the DBA scheme with optimized bandwidth allocation factor, the system can achieve a significant improvement in terms of sum average AoI, enhancing the update freshness.