Browsing by Subject "Semantic signal processing"

Now showing 1 - 4 of 4

Open Access
Enhancing reliability in semantic communication: a stochastic approach to semantic-graph modeling
(2023-09) Yetim, Sadık Yağız
Semantic communication is expected to play a critical role in reducing traffic load in future intelligent large-scale sensor networks. With advances in Machine Learning (ML) and Deep Learning (DL) techniques, design of semantically-aware systems has become feasible in recent years. This thesis focuses on improving the reliability of the semantic information represented in a graph-based language that was previously developed. Inaccuracies in the representation of the semantic information can arise due to multiple factors, such as algorithmic shortcomings or sensory errors, deteriorating the performance of the semantic extractor. This thesis aims to model the temporal evolution of semantic information, represented using the graph language, to enhance its reliability. Each unique graph configuration is treated as a distinct state, leading to a Hidden Semi-Markov Model (HSMM) defined over the state space of the graph configurations. The HSMM formulation enables the integration of prior knowledge on the semantic signal into the graph sequences, enhancing the accuracy in identifying semantic innovations. Within the HSMM framework, algorithms designed for graph smoothing, semantic information fusion, and model learning are introduced. The efficacy of these algorithms in improving the reliability of the extracted semantic-graphs is demonstrated through simulations and video streams generated in the CARLA simulation environment.
Open Access
Reliable extraction of semantic information and rate of innovation estimation for graph signals
(Institute of Electrical and Electronics Engineers , 2022-12-19) Kalfa, Mert ; Yetim, Sadık Yağız ; Atalik, Arda ; Gök, Mehmetcan; Ge, Y.; Li, R.; Tong, W.; Duman, Tolga Mete; Arıkan, Orhan
Semantic signal processing and communications are poised to play a central part in developing the next generation of sensor devices and networks. A crucial component of a semantic system is the extraction of semantic signals from the raw input signals, which has become increasingly tractable with the recent advances in machine learning (ML) and artificial intelligence (AI) techniques. The accurate extraction of semantic signals using the aforementioned ML and AI methods, and the detection of semantic innovation for scheduling transmission and/or storage events are critical tasks for reliable semantic signal processing and communications. In this work, we propose a reliable semantic information extraction framework based on our previous work on semantic signal representations in a hierarchical graph-based structure. The proposed framework includes a time integration method to increase fidelity of ML outputs in a class-aware manner, a graph-edit-distance based metric to detect innovation events at the graph-level and filter out sporadic errors, and a Hidden Markov Model (HMM) to produce smooth and reliable graph signals. The proposed methods within the framework are demonstrated individually and collectively through simulations and case studies based on real-world computer vision examples.
Open Access
Semantic and goal-oriented signal processing: semantic extraction
(2022-08) Gök, Mehmetcan
Advances in machine learning technology have enabled real-time extraction of semantic information in signals, which has the potential to revolutionize signal processing techniques and drastically improve their performance for next-generation applications. A graph-based semantic language and a goal-oriented semantic signal processing framework are adopted for structured and universal representation and efficient processing of semantic information. In the adopted framework, preprocessing of input signals is followed by a semantic extractor which identifies components from a set of application-specific predefined classes where the states, actions, and relations among the identified components are described by another application-specific predefined set called predicates. For additional information, the resulting semantic graph is also embedded with a hierarchical set of attributes. In this thesis, we focus on the crucial semantic extractor block, and to illustrate the proposed framework’s applicability, we present a real-time computer vision application on video-stream data where we adopt a tracking by detection paradigm for the identification of semantic components. Next, we show that with the adopted semantic representation and goal-filtering, the semantic signal processing framework can achieve an extremely high reduction in data rates compared to traditional approaches. Finally, we demonstrate a way to identify points of significant innovation over extended periods of time by tracking the evolution of multi-level attributes and discussing future research directions.
Open Access
Towards goal-oriented semantic signal processing: Applications and future challenges
(Elsevier, 2021-06-15) Kalfa, Mert; Gök, Mehmetcan; Atalık, Arda; Tegin, Büşra; Arıkan, Orhan; Duman, Tolga Mete
Advances in machine learning technology have enabled real-time extraction of semantic information in signals which can revolutionize signal processing techniques and improve their performance significantly for the next generation of applications. With the objective of a concrete representation and efficient processing of the semantic information, we propose and demonstrate a formal graph-based semantic language and a goal filtering method that enables goal-oriented signal processing. The proposed semantic signal processing framework can easily be tailored for specific applications and goals in a diverse range of signal processing applications. To illustrate its wide range of applicability, we investigate several use cases and provide details on how the proposed goal-oriented semantic signal processing framework can be customized. We also investigate and propose techniques for communications where sensor data is semantically processed and semantic information is exchanged across a sensor network.