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Semantic-Communication-Oriented Transmission Policy in Random Access Environment

Babaei, Alireza | 2025

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 58153 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Ashtiani, Farid
  7. Abstract:
  8. As the global demand for data has continued to increase exponentially, researchers have begun exploring the concept of semantic communication as an effective tool to meet this demand. Semantic communication transcends the boundaries of conventional telecommunication systems, focusing on the transmission as well as accurate retrieval of meaning at the source and destination, respectively, rather than transmitting and recovering merely symbols. One approach in semantic communication emphasizes the significance of information, rather than its meaning, to achieve efficient and goal-oriented communication. One key metric in goal-oriented communication is the Age of Information (AoI). AoI is a measure of freshness for an information stream, defined as the time elapsed since the generation of the most recent sample available at the destination. Another metric is the Age of Incorrect Information (AoII). AoII is a recently introduced metric for real-time remote monitoring systems. Specifically, this metric quantifies the duration for which the information at the monitor is incorrect, weighted by the magnitude of the inaccuracy, thereby combining the concepts of freshness and distortion. This research proposes a method for deriving near-optimal transmission policies based on either AoI or AoII in a resource-constrained discrete-time communication system operating over an unreliable channel with a random access protocol. First, we analyze a system in which a single transmitter with a single user or data source aims to exchange information, focusing on the average AoI metric. We then extend this system to a scenario involving a single transmitter with two users or data sources, each attempting to transmit their respective samples. Finally, we examine a remote monitoring system with a Markovian source process based on the average AoII metric. In all these scenarios, we model the problem as a constrained Markov decision process (CMDP), which is subsequently transformed into a linear programming (LP) problem. We present a method for determining a near-optimal policy. Our results demonstrate that the proposed policy closely approaches the optimal policy. Furthermore, we compare our findings with conventional slotted-ALOHA policies and some related works
  9. Keywords:
  10. Constrained Markov Decision Process ; Information Age ; Information Value ; Incorrect Information Age ; Information freshness ; Semantic Communication

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