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Yayın Improving age of information in random access channels(Institute of Electrical and Electronics Engineers Inc., 2020-07) Atabay, Doğa Can; Uysal, Elif; Kaya, OnurWe study Age of Information (AoI) in a random access channel where a number of devices try to send status updates over a common medium. Assuming a time-slotted scenario where multiple transmissions result in collision, we propose a threshold-based lazy version of Slotted ALOHA and derive the time average AoI achieved by this policy. We demonstrate that the average AoI performance of the lazy policy is significantly better than Slotted ALOHA, and close to the ideal round robin benchmark.Yayın When to pull data for minimum age penalty(IEEE, 2021-10-18) Yavaşcan, Orhan Tahir; Ceran, Elif Tuğçe; Cakir, Zeynep; Uysal, Elif; Kaya, OnurA communication receiver that wants to pull data from a remote sensor by exploiting wireless energy transfer is considered. The receiver has a long-term average energy budget for this operation, and its goal is to keep the time average of a general age penalty function as small as possible. The channel from the source to the receiver is a two-state (ON/OFF) communication link whose state is IID or Markovian, and known instantaneously by the receiver. Modeling the problem as a constrained Markov decision problem, we obtain a randomized threshold-based decision policy that achieves the minimum possible average age penalty. We determine the optimal time average Age of Information and age violation probabilities by exploiting the optimality of the derived policy.Yayın Optimizing peak age under intermittent satellite connectivity and store-and-forward(IEEE Computer Society, 2025-10-29) Arı, Çağrı; Kartal, Özkan Tuğberk; Munari, Andrea; Badia, Leonardo; Uysal, Elif; Kaya, OnurWe consider a real-time task-oriented application operating over an intermittently available satellite-based communication network, aiming to collect status updates generated by a remote sensing device. The system is modeled as a scheduling problem over a finite horizon, corresponding to the duration of the task, to minimize the peak Age of Information at the destination. The number of updates that can be transmitted is constrained by a transmission budget. Moreover, the status updates are subject to delays caused by the store-and-forward operation of the satellites, which may vastly vary depending on the network conditions. We investigate three levels of awareness regarding the connectivity conditions of the satellite network: (i) scheduling without any information about connectivity conditions, (ii) scheduling based solely on the current conditions, and (iii) scheduling based on full connectivity knowledge. The first case admits a relatively simple structure, for which a periodic transmission strategy is adopted. The latter two cases are formulated as semi-Markov decision processes and solved to obtain the optimal transmission scheduling policy. Simulation results demonstrate the impact of connectivity awareness on the application performance at the destination. Through a simple modeling approach, we provide first insights into the practically relevant setting of store-and-forward satellite architectures.
