AoI-Aware Power Control and Subcarrier Assignment in D2D-Aided Underlaying Cellular Networks for High-Speed Railways
Difei Jia, Fengye Hu, Zhuang Ling, Shun Na
Abstract
This paper investigates a high-speed railway (HSR) network with device-to-device (D2D)-aided underlaying cellular communications, where cellular-based train-to-infrastructure (T2I) and D2D-supported train-to-train (T2T) transmissions co-exist. Considering the diverse quality-of-service (QoS) requirements of different types of links, age of information (AoI) is adopted as a new metric to evaluate the information freshness performance of T2T links. With the objective to maximize the sum data rate of T2I links, we formulate a resource allocation problem under the minimum data rate constraints of T2I links and the maximum average AoI constraint of T2T links. As the problem with a set of binary variables, it is intractable to be solved directly. Thus, we propose an AoI-aware power control and subcarrier assignment (AoI-PCSA) scheme, which decomposes the optimization problem into a power control subproblem and a subcarrier assignment subproblem. More specifically, we derive the optimal analytical solutions of power control for each T2I-T2T subcarrier reusing pair with algebraic methods. Then, we transform the subcarrier assignment subproblem into a weighted bipartite matching problem and obtain the optimal reusing pattern based on the Kuhn-Munkres algorithm. Simulation results demonstrate that our proposed scheme can achieve a sum data rate gain of up to 19.94% on average for T2I links as compared with other benchmark schemes.