Scheduling and queue management for information freshness in multi-source status update systems
| buir.advisor | Akar, Nail | |
| dc.contributor.author | Gamgam, Ege Orkun | |
| dc.date.accessioned | 2023-10-05T08:36:30Z | |
| dc.date.available | 2023-10-05T08:36:30Z | |
| dc.date.copyright | 2023-09 | |
| dc.date.issued | 2023-09 | |
| dc.date.submitted | 2023-10-04 | |
| dc.description | Cataloged from PDF version of article. | |
| dc.description | Thesis (Ph.D.): Bilkent University, Department of Electrical and Electronics Engineering, İhsan Doğramacı Bilkent University, 2023. | |
| dc.description | Includes bibliographical references (leaves 118-129). | |
| dc.description.abstract | Timely delivery of information to its intended destination is essential in many ex-isting and emerging time-sensitive applications. While conventional performance metrics like delay, throughput, or loss have been extensively studied in the literature, research concerning the management of age-sensitive traffic is relatively immature. Recently, a number of information freshness metrics have been intro-duced for quantifying the timeliness of information in networked systems carrying age-sensitive traffic, primarily the Age of Information (AoI) and peak AoI (PAoI) metrics as well as their alternatives including Age of Synchronization (AoS), ver-sion age, binary freshness, etc. The focus of this thesis is the development and performance modeling of age-agnostic scheduling and queue management policies in various multi-source status update systems carrying age-sensitive traffic, using the recently introduced information freshness metrics. In this thesis, first, the exact distributions of the AoI and PAoI for the probabilistic Generate-At-Will (GAW) and Random Arrival with Single Buffer (RA-SB) servers are studied with general number of heterogeneous information sources with phase-type (PH-type) service time distributions for which an absorbing Continuous-Time Markov Chains (CTMC) based analytical modeling method, namely AMC (Absorbing Markov Chains) method, is proposed. Secondly, a homogeneous multi-source status update system with Poisson information packet arrivals and exponentially distributed service times is studied for which the server is equipped with a queue holding the freshest packet from each source referred to as Single Buffer Per-Source Queueing (SBPSQ). For this case, two SBPSQ-based scheduling policies are studied, namely First Source First Serve (FSFS) and the Earliest Served First Serve (ESFS) policies, using the AMC method, and it is shown that ESFS presents a promising scheduler for this special setting. Third, a general status update system with two heterogeneous information sources is studied, i.e., sources have different priorities and generally distributed service times, for Deterministic GAW (D-GAW) and Deterministic RA-SB (D-RA-SB) servers. The aim in both servers is to minimize the system AoI/AoS that is time-averaged and weighted across the two sources. For the D-GAW server, the optimal update policy is obtained in closed form. A packet replacement policy, referred to as Pattern-based Replacement (PR) policy, is then proposed for the D-RA-SB server based on the optimal policy structure of the D-GAW server. Finally, scheduling in a cache update system is investigated where a remote server delivers time-varying contents of multiple items with heterogeneous popularities and service times to a local cache so as to maximize the weighted sum binary freshness of the system, and the server is equipped with a queue that holds the most up-to-date content for each item. A Water-filling based Scheduling (WFS) policy and its extension, namely Extended WFS (E-WFS) policy, are proposed based on convex optimization applied to a relaxation of the original system, with low computational complexity and near optimal weighted sum binary freshness performance. | |
| dc.description.provenance | Made available in DSpace on 2023-10-05T08:36:30Z (GMT). No. of bitstreams: 1 B162548.pdf: 2606725 bytes, checksum: 8e836b39f8b86fbb12359ac4f7e84b0c (MD5) Previous issue date: 2023-10 | en |
| dc.description.statementofresponsibility | by Ege Orkun Gamgam | |
| dc.format.extent | xiv, 229 leaves : illustrations, charts ; 30 cm. | |
| dc.identifier.itemid | B162548 | |
| dc.identifier.uri | https://hdl.handle.net/11693/113920 | |
| dc.language.iso | English | |
| dc.rights | info:eu-repo/semantics/openAccess | |
| dc.subject | Status update systems | |
| dc.subject | Age of information | |
| dc.subject | Binary freshness | |
| dc.subject | Scheduling | |
| dc.subject | Queue management | |
| dc.subject | Absorbing Markov chains | |
| dc.subject | Markov decision processes | |
| dc.subject | Convex optimization | |
| dc.title | Scheduling and queue management for information freshness in multi-source status update systems | |
| dc.title.alternative | Çok kaynaklı bilgi güncelleme çok kaynaklı bilgi güncelleme tazelliği için çizelgeleme ve kuyruk yönetimi | |
| dc.type | Thesis | |
| thesis.degree.discipline | Electrical and Electronic Engineering | |
| thesis.degree.grantor | Bilkent University | |
| thesis.degree.level | Doctoral | |
| thesis.degree.name | Ph.D. (Doctor of Philosophy) |