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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
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Publication Metadata only Frequency-domain model of microfluidic molecular communication channels with graphene BioFET-based receivers(Institute of Electrical and Electronics Engineers Inc., 2024) Department of Electrical and Electronics Engineering; Kuşcu, Murat; Abdalı, Ali; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and EngineeringMolecular Communication (MC) is a bio-inspired communication paradigm utilizing molecules for information transfer. Research on MC has largely transitioned from theoretical investigations to practical testbed implementations, harnessing microfluidics and sensor technologies. Accurate models for input-output relationships on these platforms are crucial for optimizing MC methods and understanding the impact of physical parameters on performance. Our study focuses on a practical microfluidic MC system with a graphene field effect transistor biosensor (bioFET)-based receiver, developing an end-to-end frequency-domain model. The model provides insights into the dispersion, distortion, and attenuation of received signals, thus potentially informing the design of new frequency-domain MC techniques, such as modulation and detection methods. The accuracy of the developed model is verified through particle-based spatial stochastic simulations of pulse transmission and ligand-receptor reactions on the receiver surface.Publication Metadata only Association of visual-based signals with electroencephalography patterns in enhancing the drowsiness detection in drivers with obstructive sleep apnea(Multidisciplinary Digital Publishing Institute (MDPI), 2024) Peker, Nur Yasin; Hakkoz, Mustafa Abdullah; Erdem, Ciğdem Eroğlu; Department of Electrical and Electronics Engineering; Minhas, Riaz; Arbatlı, Semih; Çelik, Yeliz; Gürsoy, Beren Semiz; Peker, Yüksel; Department of Electrical and Electronics Engineering; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); Graduate School of Sciences and Engineering; Graduate School of Health Sciences; School of Medicine; College of EngineeringIndividuals with obstructive sleep apnea (OSA) face increased accident risks due to excessive daytime sleepiness. PERCLOS, a recognized drowsiness detection method, encounters challenges from image quality, eyewear interference, and lighting variations, impacting its performance, and requiring validation through physiological signals. We propose visual-based scoring using adaptive thresholding for eye aspect ratio with OpenCV for face detection and Dlib for eye detection from video recordings. This technique identified 453 drowsiness (PERCLOS ≥ 0.3Publication Metadata only Intelligent surfaces empowered wireless network: recent advances and the road to 6G(Institute of Electrical and Electronics Engineers Inc, 2024) Wu, Qingqing; Zheng, Beixiong; You, Changsheng; Zhu, Lipeng; Shen, Kaiming; Shao, Xiaodan; Mei, Weidong; Di, Boya; Zhang, Hongliang; Song, Lingyang; Di Renzo, Marco; Luo, Zhi-Quan; Zhang, Rui; Department of Electrical and Electronics Engineering; Başar, Ertuğrul; Department of Electrical and Electronics Engineering; College of EngineeringIntelligent surfaces (ISs) have emerged as a key technology to empower a wide range of appealing applications for wireless networks, due to their low cost, high energy efficiency, flexibility of deployment, and capability of constructing favorable wireless channels/radio environments. Moreover, the recent advent of several new IS architectures further expanded their electromagnetic functionalities from passive reflection to active amplification, simultaneous reflection, and refraction, as well as holographic beamforming. However, the research on ISs is still in rapid progress and there have been recent technological advances in ISs and their emerging applications that are worthy of a timely review. Thus, in this article, we provide a comprehensive survey on the recent development and advances of ISs-aided wireless networks. Specifically, we start with an overview on the anticipated use cases of ISs in future wireless networks such as 6G, followed by a summary of the recent standardization activities related to ISs. Then, the main design issues of the commonly adopted reflection-based IS and their state-of-the-art solutions are presented in detail, including reflection optimization, deployment, signal modulation, wireless sensing, and integrated sensing and communications. Finally, recent progress and new challenges in advanced IS architectures are discussed to inspire future research.Publication Metadata only Deep photonic network platform enabling arbitrary and broadband optical functionality(Nature Portfolio, 2024) ; Department of Electrical and Electronics Engineering; Amiri, Ali Najjar; Vit, Aycan Deniz; Görgülü, Kazım; Mağden, Emir Salih; Department of Electrical and Electronics Engineering; ; Graduate School of Sciences and Engineering; College of Engineering;Expanding applications in optical communications, computing, and sensing continue to drive the need for high-performance integrated photonic components. Designing these on-chip systems with arbitrary functionality requires beyond what is possible with physical intuition, for which machine learning-based methods have recently become popular. However, computational demands for physically accurate device simulations present critical challenges, significantly limiting scalability and design flexibility of these methods. Here, we present a highly-scalable, physics-informed design platform for on-chip optical systems with arbitrary functionality, based on deep photonic networks of custom-designed Mach-Zehnder interferometers. Leveraging this platform, we demonstrate ultra-broadband power splitters and a spectral duplexer, each designed within two minutes. The devices exhibit state-of-the-art experimental performance with insertion losses below 0.66 dB, and 1-dB bandwidths exceeding 120 nm. This platform provides a tractable path towards systematic, large-scale photonic system design, enabling custom power, phase, and dispersion profiles for high-throughput communications, quantum information processing, and medical/biological sensing applications. An efficient and physically accurate platform is required to rapidly design high-performance integrated photonic devices. Here, the authors present a scalable framework for creating on-chip optical systems with complex and arbitrary functionality.Publication Metadata only Noise modulation(IEEE-Institute of Electrical and Electronics Engineers, 2024) Department of Electrical and Electronics Engineering; Başar, Ertuğrul; Department of Electrical and Electronics Engineering; College of EngineeringInstead of treating the noise as a detrimental effect, can we use it as an information carrier? In this letter, we provide the conceptual and mathematical foundations of wireless communication utilizing noise and random signals in general. Mainly, the concept of noise modulation (NoiseMod) is introduced to cover information transmission by both thermal noise and externally generated noise signals. The performance of underlying NoiseMod schemes is evaluated under both additive white Gaussian and fading channels and alternative NoiseMod designs exploiting non-coherent detection and time diversity are proposed. Extensive numerical and computer simulation results are presented to validate our designs and theoretical derivations.Publication Metadata only Coordinate interleaved OFDM with repeated in-phase/quadrature index modulation(IEEE-Inst Electrical Electronics Engineers Inc, 2024) ; Department of Electrical and Electronics Engineering; Tuğtekin, Ömer Furkan; Doğukan, Ali Tuğberk; Arslan, Emre; Başar, Ertuğrul; Department of Electrical and Electronics Engineering; ; Graduate School of Sciences and Engineering; College of Engineering; Communications Research and Innovation Laboratory (CoreLab)Orthogonal frequency division multiplexing with index modulation (OFDM-IM), which transmits information bits through ordinary constellation symbols and indices of active subcarriers, is a promising multicarrier transmission scheme and has attracted the attention of researchers due to numerous benefits such as flexibility and simplicity. Nonetheless, OFDM-IM cannot satisfy the needs of future wireless communication services such as superior reliability, high data rates, and low complexity. In this article, we propose a novel OFDM-IM scheme named coordinate interleaved OFDM with repeated in-phase/quadrature IM (CI-OFDM-RIQIM), which provides superior error performance and enhanced spectral efficiency due to its diversity order of two and clever subcarrier activation pattern (SAP) detection mechanism, respectively. In addition, CI-OFDM-RIQIM is further extended to coordinate interleaved OFDM with in-phase/quadrature IM (CI-OFDM-IQIM) by doubling information bits transmitted by IM. Furthermore, log-likelihood ratio (LLR) based low-complexity detectors are designed for both proposed schemes. Theoretical analyses are performed and an upper bound on the bit error probability is derived. Comprehensive computer simulations under perfect and imperfect channel state information (CSI), are conducted to compare the proposed and reference schemes. It is shown that CI-OFDM-RIQIM and CI-OFDM-IQIM show superior results and can be considered promising candidates for next-generation wireless communication systems.Publication Metadata only Index modulation-based information harvesting for far-field RF power transfer(IEEE-Inst Electrical Electronics Engineers Inc, 2024) İlter, Mehmet C.; Wichman, Risto; Hamalainen, Jyri; Department of Electrical and Electronics Engineering; Pıhtılı, Mehmet Ertuğ; Başar, Ertuğrul; Department of Electrical and Electronics Engineering; ; Graduate School of Sciences and Engineering; College of Engineering; Communications Research and Innovation Laboratory (CoreLab)As wireless information transmission (WIT) progresses into its sixth generation (6G), a challenge arises in sustaining terminal operations with limited batteries for Internet-of-Things (IoT) platforms. To address this, wireless power transfer (WPT) emerges as a solution, empowering battery-less infrastructures and enabling nodes to harvest energy for sustainable operations. Thus, the eclectic integration of WPT with WIT mechanisms becomes crucial to mitigate the need for battery replacements while providing secure and reliable communication. A novel protocol that amalgamates WIT and WPT called Information Harvesting (IH) has recently been proposed to effectively handle challenges in wireless information and power transfer (WIPT) by employing index modulation (IM) techniques for data communication atop the existing far-field WPT mechanism. This paper presents a unified framework for IM-based IH mechanisms and evaluates their energy harvesting capability, bit error rate (BER), and ergodic secrecy rate (ESR) performance for diverse IM schemes. The findings indicate the significant potential of the IM-based IH mechanism in facilitating reliable data communication within existing far-field WPT systems while underscoring promising refinements in green and secure communication paradigms for next-generation IoT wireless networks. AuthorsPublication Metadata only Reconfigurable intelligent surfaces for 6G: emerging hardware architectures, applications, and open challenges(IEEE-Institute of Electrical and Electronics Engineers, 2024) Alexandropoulos, George C.; Liu, Yuanwei; Wu, Qingqing; Jin, Shi; Yuen, Chau; Dobre, Octavia A.; Schober, Robert; Department of Electrical and Electronics Engineering; Başar, Ertuğrul; Department of Electrical and Electronics Engineering; College of EngineeringReconfigurable intelligent surfaces (RISs) are rapidly gaining prominence in the realm of 5G-advanced and predominantly 6G mobile networks, offering a revolutionary approach to optimizing wireless communications. This article delves into the intricate world of the RIS technology, exploring its diverse hardware architectures and the resulting versatile operating modes. These include RISs with signal reception and processing units, sensors, amplification units, transmissive capability, multiple stacked components, and dynamic metasurface antennas (DMAs). Furthermore, we shed light on emerging RIS applications, such as index and reflection modulation, noncoherent modulation, next-generation multiple access (NGMA), integrated sensing and communications (ISAC), energy harvesting (EH), as well as aerial and vehicular networks. These exciting applications are set to transform the way we will wirelessly connect in the upcoming era of 6G. Finally, we review recent experimental RIS setups and present various open problems of the overviewed RIS hardware architectures and their applications. From enhancing network coverage to enabling new communication paradigms, RIS-empowered connectivity is poised to play a pivotal role in shaping the future of wireless networking. This article unveils the underlying principles and potential impacts of RISs, focusing on cutting-edge developments of this physical-layer smart connectivity technology.Publication Metadata only Pairwise sequency index modulation with OTSM for green and robust single-carrier communications(IEEE-Institute of Electrical and Electronics Engineers, 2024) Doosti-Aref, Abed; Masouros, Christos; Arslan, Huseyin; Department of Electrical and Electronics Engineering; Başar, Ertuğrul; Department of Electrical and Electronics Engineering; College of EngineeringIn this letter, inspired by the fundamental thoughts of sequency index modulation (SeIM) and orthogonal time sequency multiplexing (OTSM), a novel technique is introduced for green and robust single-carrier communications in wireless networks. More specifically, pairwise SeIM (PSeIM) is proposed as a novel indexing scheme making SeIM robust to error propagation and significantly reduces the peak power of SeIM-based systems with a lower complexity of detection. Analytical results are presented for the bit error rate (BER), peak-to-average power ratio (PAPR), and spectral efficiency to reveal the trade-off and advantages in PSeIM-OTSM. Simulation and analytical results verify that for 4-QAM uncoded data, PSeIM-OTSM outperforms OTSM by 50% in terms of both PAPR and complexity of detection along with 125.32% energy efficiency improvement to achieve a BER of 10-8 in high mobility doubly spread channels.Publication Metadata only Index modulation aided fragmented spectra centralization in OTFS systems(IEEE-Institute of Electrical and Electronics Engineers, 2024) Zhang, Bo; Mei, Lin; Du, Zhaopeng; Teh, Kah Chan; Department of Electrical and Electronics Engineering; Başar, Ertuğrul; Department of Electrical and Electronics Engineering; College of EngineeringBy selecting various active-silent combinations, classical frequency-domain index modulation (IM) generates numerous energy-free subcarriers dispersed across subblocks, which we refer to as the fragmented spectra. This letter proposes a novel IM approach aimed at collecting the fragmented spectra in subblocks to form a completely unused frequency band, called the IM-aided fragmented spectra centralization (IM-FSC). Specifically, within each subblock, if the last subcarrier is to be activated, we transfer this active position to the first unactivated subcarrier and employ a distinguishable constellation to modulate the symbol on this subcarrier. Through this approach, each subblock contributes one energy-free subcarrier, and the unused frequency band can be obtained accordingly by combining these fragmented spectra from multiple subblocks. We designate this unoccupied frequency band as zero padding (ZP) and guard interval for interference cancellation and channel estimation in orthogonal time frequency space (OTFS) system. The closed-form expressions of bit error rate (BER) and generalization guidelines are also derived. Simulation results demonstrate the promising communication capability and channel estimation accuracy of the proposed scheme.