A Topology Optimization Algorithm for Minimizing Information Age in Two-hop Wireless Networks

Age of Information (AoI) has been proposed as a new metric to quantify data freshness from the point of destination. In this research, the problem of minimizing AoI in orthogonal frequency division multiplexing (OFDM) wireless networks is focused on. Since all existing works assume that the network topology is given and then propose the efficient scheduling algorithms on the basis of given topology, a study is focused on the work for AoI optimization with topology control in a two-hop OFDM-based wireless networks. Firstly, under the Poisson arrival service model, the mathematical expressions of AoI from the source node to the relay node and from the relay node to the aggregation node are derived, revealing the nonlinear relationship between AoI and network load rate. The lower bound of the average AoI of whole network is theoretically analyzed, and the optimal load rate is proved to be 0.457. Furthermore, a two-stage relay node selection algorithm is designed in the OFDM scenario, taking into account key parameters such as packet size, transmission distance, and channel rate, in which the optimal relay node is selected based on the load rate and theoretical optimal threshold. The simulation results show that the algorithm is significantly better than the baseline strategies under various network density, load, and data size conditions, with an average AoI reduction of 32 percentage point.