Optimizing Information Freshness in a Multiple Access Channel With Heterogeneous Devices

• Published in: IEEE open journal of the Communications Society Vol. 2; pp. 456 - 470
• Main Authors: Chen, Zheng, Pappas, Nikolaos, Bjornson, Emil, Larsson, Erik G.
• Format: Journal Article
• Language: English
• Published: New York IEEE 2021; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Age of information; Algorithms; Batteries; Electric power grids; Energy harvesting; Lyapunov optimization; Multiple access; multiple access channel; Nodes; Optimization; Packets (communication); Power system stability; Queueing analysis; Random access; Receivers; Scheduling; Signal to noise ratio; Stability; Statistical analysis; Stochastic processes; Wireless sensor networks
• ISSN: 2644-125X; 2644-125X
• DOI: 10.1109/OJCOMS.2021.3062678

In this work, we study age-optimal scheduling with stability constraints in a multiple access channel with two heterogeneous source nodes transmitting to a common destination. The first node is connected to a power grid and it has randomly arriving data packets. Another energy harvesting (EH) sensor monitors a stochastic process and sends status updates to the destination. We formulate an optimization problem that aims at minimizing the average age of information (AoI) of the EH node subject to the queue stability condition of the grid-connected node. First, we consider a Probabilistic Random Access (PRA) policy where both nodes make independent transmission decisions based on some fixed probability distributions. We show that with this policy, the average AoI is equal to the average peak AoI, if the EH node only sends freshly generated samples. In addition, we derive the optimal solution in closed form, which reveals some interesting properties of the considered system. Furthermore, we consider a Drift-Plus-Penalty (DPP) policy and develop AoI-optimal and peak-AoI-optimal scheduling algorithms using the Lyapunov optimization theory. Simulation results show that the DPP policy outperforms the PRA policy in various scenarios, especially when the destination node has low multi-packet reception capabilities.