Ildız, Muhammed Emrullah
We study a pull-based status update communication model where a source node submits update packets to a channel with random transmission delay, at times requested by a remote destination node. The objective is to minimize the average query-age-of-information (QAoI), defined as the age of information (AoI) measured at query instants that occur at the destination side according to a stochastic arrival process. In reference to a push-based problem formulation defined in the literature where the source decides to update or wait at will, with the objective of minimizing the time average AoI at the destination, we name this problem the Pull-or-Wait (PoW) problem. We provide a comparison of the two formulations: (i) Under Poisson query arrivals and random transmission delay, an optimal policy that minimizes the time average AoI also minimizes the average QAoI, and these minimum values are equal; and (ii) the optimal average QAoI is shown to be less than or equal to the optimal time average AoI under the following two cases: (1) Periodic query arrivals and random transmission delay and (2) general query arrivals and constant transmission delay. We identify the PoW problem in the case of a single query as a stochastic shortest path (SSP) problem with uncountable state and action spaces, which has been not solved in previous literature. We derive an optimal solution for this SSP problem and use it as a building block for the solution of the PoW problem under periodic query arrivals.


An Inequality for Query Age of Information and Age of Information Sorgu Ani Bilgi Yaşi (QAoI) ve Ortalama Bilgi Yaşi (AoI) Arasinda bir Eşitsizlik
Ildiz, M. Emrullah; Avsar, Semanur; Uysal, Elif (2022-01-01)
We study a status update system where a destination node requests from a source node to submit update packets to a channel. The update packets incur a constant transmission delay in the channel. The update packets sent from the source node will be utilized by the destination node at certain query instants generated toward a computation. The query instants are modeled as a stochastic arrival process. The Age of Information (AoI) at the query instants is called as the Query Age of Information (QAoI). The pull...
Update or Wait: How to Keep Your Data Fresh
Sun, Yin; Uysal, Elif; Yates, Roy D.; Koksal, C. Emre; Shroff, Ness B. (2017-11-01)
In this paper, we study how to optimally manage the freshness of infimmation updates sent from a source node to a destination via a channel. A proper metric for data freshness at the destination is the age-of-information, or simply age, which is defined as how old the freshest received update is, since the moment that this update was generated at the source node (e.g., a sensor). A reasonable update policy is the zero wait policy, i.e., the source node submits a fresh update once the previous update is deli...
Age-aware scheduling in communication networks
Beytur, Hasan Burhan; Uysal, Elif; Department of Electrical and Electronics Engineering (2020-10-30)
In next-generation communication networks, various types of data traffic with different requirements will coexist. This type of coexistence requires new techniques based on new metrics to distinguish the various types of data traffic based on their value. The emerging metric Age of Information (AoI) quantifying the timeliness of the communication flow is a promising metric to prepare future networks for new technologies such as the Internet of Things and Autonomous Driving. In this thesis, we studied s...
Cooperative Network Coded ARQ Strategy for Broadcast Networks
Tutgun, Rasit; AKTAŞ, EMRE (2015-06-12)
A novel cooperative automatic repeat request (ARQ) method with network coding is proposed for broadcast networks where single source node broadcasts multiple packets to multiple destinations. Upon a failed transmission, multiple relays cooperate with the source node at the retransmission phase, where network coding is used to combine multiple lost packets. A random access mechanism is employed where retransmission is done according to back-off counters. The proposed method employs the back-off mechanism to ...
Relay Selection for Efficient HARQ-IR Protocols in Relay-Assisted Multisource Multicast Networks
Quoc-Tuan Vien, Quoc-Tuan Vien; Nguyen, Huan X.; Shah, Purav; Ever, Enver; Duc To, Duc To (2014-05-21)
This paper investigates relay selection for reliable data transmission in relay-assisted multisource multicast networks (RMMNs) where multiple source nodes distribute information to a set of destination nodes with the assistance of multiple relay nodes. Hybrid automatic repeat request with incremental redundancy (HARQ-IR) is used and supported by either a physical-layer network coding (PNC) or an analog network coding (ANC) technique employed at the relays. By deriving efficiency metrics of the HARQ-IR prot...
Citation Formats
M. E. Ildız, “QUERY AGE OF INFORMATION IN COMMUNICATION NETWORKS,” M.S. - Master of Science, Middle East Technical University, 2002.