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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
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Publication Metadata only Microfluidic pulse shaping methods for molecular communications(Elsevier, 2023) Department of Electrical and Electronics Engineering; Kahvazi Zadeh, Maryam; Bolhassan, Iman Mokari; Kuşcu, Murat; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of EngineeringMolecular Communication (MC) is a bio-inspired communication modality that utilizes chemical signals in the form of molecules to exchange information between spatially separated entities. Pulse shaping is an important process in all communication systems, as it modifies the waveform of transmitted signals to match the characteristics of the communication channel for reliable and high-speed information transfer. In MC systems, the unconventional architectures of components, such as transmitters and receivers, and the complex, nonlinear, and time-varying nature of MC channels make pulse shaping even more important. While several pulse shaping methods have been theoretically proposed for MC, their practicality and performance are still uncertain. Moreover, the majority of recently proposed experimental MC testbeds that rely on microfluidics technology lack the incorporation of programmable pulse shaping methods, which hinders the accurate evaluation of MC techniques in practical settings. To address the challenges associated with pulse shaping in microfluidic MC systems, we provide a comprehensive overview of practical microfluidic chemical waveform generation techniques that have been experimentally validated and whose architectures can inform the design of pulse shaping methods for microfluidic MC systems and testbeds. These techniques include those based on hydrodynamic and acoustofluidic force fields, as well as electrochemical reactions. We also discuss the fundamental working mechanisms and system architectures of these techniques, and compare their performances in terms of spatiotemporal resolution, selectivity, system complexity, and other performance metrics relevant to MC applications, as well as their feasibility for practical MC applications.Publication Metadata only Joint pulse index and spatial modulation(Institute of Electrical and Electronics Engineers, 2024) Aldirmaz-Colak, Sultan; Aydin, Erdogan; Gundem, Sumeyra; Celik, Yasin; Department of Electrical and Electronics Engineering; Başar, Ertuğrul; Department of Electrical and Electronics Engineering; College of EngineeringAccording to the planned key performance indicator (KPI) standards, 6G technology should achieve higher throughput than 5G. More efficiency in transceiver schemes is required to meet this demand. In this study, we take advantage of spatial modulation (SM) and pulse index modulation (PIM) techniques to increase spectral efficiency. The proposed PIM-SM scheme utilizes well-localized and orthogonal Hermite-Gaussian pulses along with spatial indexing. Thanks to the orthogonality between pulses in the set, multiple pulses are transmitted together. The design, simulation, and analytical bit error rate performance derivations of PIM-SM are discussed in this letter to verify the viability and compatibility of pulse-based data transfer utilizing the spatial domain. The performance is compared with generalized code index modulation-spatial modulation (GCIM-SM), code index modulation-quadrature spatial modulation (CIM-QSM), and classical spatial modulation (SM) schemes.Publication Metadata only Stabilization and adiabatic control of antiferromagnetically coupled skyrmions without the topological hall effect(Royal Soc Chemistry, 2023) Department of Electrical and Electronics Engineering; Yağan, Rawana; Cheghabouri, Arash Mousavi; Onbaşlı, Mehmet Cengiz; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of EngineeringSynthetic antiferromagnetically coupled (SAF) multilayers provide different physics of stabilizing skyrmions while eliminating the topological Hall effect (THE), enabling efficient and stable control. The effects of material parameters, external current drive, and a magnetic field on the skyrmion equilibrium and propagation characteristics are largely unresolved. Here, we present a computational and theoretical demonstration of the large window of material parameters that stabilize SAF skyrmions determined by saturation magnetization, uniaxial anisotropy, and Dzyaloshinskii-Moriya interaction. Current-driven SAF skyrmion velocities reach & SIM;200 m s(-1) without the THE. The SAF velocities are about 3-10 times greater than the typical ferromagnetic skyrmion velocities. The current densities needed for driving SAF skyrmions could be reduced to 10(8) A m(-2), while 10(11) A m(-2) or above is needed for ferromagnetic skyrmions. By reducing the SAF skyrmion drive current by 3 orders, Joule heating is reduced by 6 orders of magnitude. These results pave the way for new SAF interfaces with improved equilibrium, dynamics, and power savings in THE-free skyrmionics.Publication Metadata only Received signal and channel parameter estimation in molecular communications(IEEE-Inst Electrical Electronics Engineers Inc, 2024) ; Department of Electrical and Electronics Engineering; Baydaş, O. Tansel; Akan, Özgür Barış; Department of Electrical and Electronics Engineering; ; College of Engineering;Molecular communication (MC) is a paradigm that employs molecules as information carriers, hence, requiring unconventional transceivers and detection techniques for the Internet of Bio-Nano Things (IoBNT). In this study, we provide a novel MC model that incorporates a spherical transmitter and receiver with partial absorption. This model offers a more realistic representation than receiver architectures in literature, e.g., passive or entirely absorbing configurations. An optimization-based technique utilizing particle swarm optimization (PSO) is employed to accurately estimate the cumulative number of molecules received. This technique yields nearly constant correction parameters and demonstrates a significant improvement of 5 times in terms of root mean square error (RMSE) compared to the literature. The estimated channel model provides an approximate analytical impulse response;hence, it is used for estimating channel parameters such as distance, diffusion coefficient, or a combination of both. The iterative maximum likelihood estimation (MLE) is applied for the parameter estimation, which gives consistent errors compared to the estimated Cramer-Rao Lower Bound (CLRB).Publication Metadata only Molecular beamforming for actuation in molecular communication networks(IEEE-Inst Electrical Electronics Engineers Inc, 2024) Pusane, Ali E.; Yılmaz, H. Birkan; Tuğcu, Tuna; Department of Electrical and Electronics Engineering; Angjo, Joana; Başar, Ertuğrul; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of EngineeringThe actuation accuracy of sensing tasks performed by molecular communication (MC) schemes is a very important metric. Reducing the effect of sensors fallibility can be achieved by improvements and advancements in the sensor and communication networks design. Inspired by the technique of beamforming used extensively in radio frequency communication systems, a novel molecular beamforming design is proposed in this paper. This design can find application in tasks related to actuation of nano machines in MC networks. The main idea behind the proposed scheme is that the utilization of more sensing nano machines in a network can increase the overall accuracy of that network. In other words, the probability of an actuation error reduces as the number of sensors that collectively take the actuation decision increases. In order to achieve this, several design procedures are proposed. Three different scenarios for the observation of the actuation error are investigated. For each case, the analytical background is provided and compared with the results obtained by computer simulations. The improvement in the actuation accuracy by means of molecular beamforming is verified for a uniform linear array as well as for a random topology.Publication Metadata only Guest editorial special feature on bio-chem-ICTs: synergies between bio/nanotechnologies and molecular communications(IEEE-Inst Electrical Electronics Engineers Inc, 2023) Stano, Pasquale; Egan, Malcolm; Barros, Michael T.; Ünlütürk, Bige Deniz; Payne, Gregory F.; Department of Electrical and Electronics Engineering; Kuşcu, Murat; Department of Electrical and Electronics Engineering; ; College of Engineering;The Transfer of 'information' via molecules is a theme that resonates across the realm of nature, underlying collective behavior, homeostasis, and many disorders and diseases, and potentially holding the answers to some of the life's most profound questions. The prospects of understanding and manipulating this natural modality of communication have attracted a significant research interest from information and communication theorists (ICT) over the past two decades. The aim is to provide novel means of understanding and engineering biological systems. These efforts have produced substantial body of literature that sets the groundwork for bio-inspired, artificial Molecular Communication (MC) systems. This ICT-based perspective has also contributed to the understanding of natural MC, with many of the results from these endeavors being published in this journal.Publication Metadata only Ratio shift keying modulation for time-varying molecular communication channels(IEEE-Inst Electrical Electronics Engineers Inc, 2024) Department of Electrical and Electronics Engineering; Araz, Mustafa Okan; Emirdağı, Ahmet Rasim; Kopuzlu, Mahmut Serkan; Kuşcu, Murat; Department of Electrical and Electronics Engineering; College of EngineeringMolecular Communications (MC) is a bio-inspired communication technique that uses molecules to encode and transfer information. Many efforts have been devoted to developing novel modulation techniques for MC based on various distinguishable characteristics of molecules, such as their concentrations or types. In this paper, we investigate a particular modulation scheme called Ratio Shift Keying (RSK), where the information is encoded in the concentration ratio of two different types of molecules. RSK modulation is hypothesized to enable accurate information transfer in dynamic MC scenarios where the time-varying channel characteristics affect both types of molecules equally. To validate this hypothesis, we first conduct an information-theoretical analysis of RSK modulation and derive the capacity of the end-to-end MC channel where the receiver estimates concentration ratio based on ligand-receptor binding statistics in an optimal or suboptimal manner. We then analyze the error performance of RSK modulation in a practical time-varying MC scenario, that is mobile MC, in which both the transmitter and the receiver undergo diffusion-based propagation. Our numerical and analytical results, obtained for varying levels of similarity between the ligand types used for ratio-encoding, and varying number of receptors, show that RSK can significantly outperform the most commonly considered MC modulation technique, concentration shift keying (CSK), in dynamic MC scenarios.Publication Metadata only Microfluidic molecular communication transmitter based on hydrodynamic gating(IEEE-Inst Electrical Electronics Engineers Inc, 2024) ; Department of Electrical and Electronics Engineering; Bolhassan, Iman Mokari; Abdalı, Ali; Department of Electrical and Electronics Engineering; ; Graduate School of Sciences and Engineering; College of Engineering;Molecular Communications (MC) is a bio-inspired paradigm for transmitting information using chemical signals, which can enable novel applications at the junction of biotechnology, nanotechnology, and information and communication technologies. However, designing efficient and reliable MC systems poses significant challenges due to the complex nature of the physical channel and the limitations of the micro/nanoscale transmitter and receiver devices. In this paper, we propose a practical microfluidic transmitter architecture for MC based on hydrodynamic gating, a widely utilized technique for generating chemical waveforms in microfluidic channels with high spatiotemporal resolution. We develop an approximate analytical model that can capture the fundamental characteristics of the generated molecular pulses, such as pulse width, pulse amplitude, and pulse delay, as functions of main system parameters, such as flow velocity and gating duration. We validate the accuracy of our model by comparing it with finite element simulations using COMSOL Multiphysics under various system settings. Our analytical model can enable the optimization of microfluidic transmitters for MC applications in terms of minimizing intersymbol interference and maximizing data transmission rate.Publication Metadata only OFDM-based information harvesting(IEEE-Inst Electrical Electronics Engineers Inc, 2024) İlter, Mehmet C.; Wichman, Risto; 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)Considering the current capability in hardware design, wireless power transmission enables the next stage in the current consumer electronics revolution by reducing the dependency on the lifetime of the batteries in the devices. Information harvesting (IH) introduced a novel mechanism by enabling information transmission to the existing far-field wireless power transfer mechanisms. To do so, information bits are embedded into a transmitter entity at the wireless power transmitter inspired by index modulation techniques creating a communication link without sacrificing the operational objectives of the power transmitter. This letter proposes a new IH mechanism on top of orthogonal frequency division multiplexing-based far-field wireless power transfer mechanism. The benefits of the proposed IH mechanism are investigated in terms of harvested energy, achievable rate and reliability.Publication Metadata only Autoencoder-based enhanced orthogonal time frequency space modulation(IEEE-Inst Electrical Electronics Engineers Inc, 2023) Department of Electrical and Electronics Engineering; Tek, Yusuf İslam; Doğukan, Ali Tuğberk; Başar, Ertuğrul; Department of Electrical and Electronics Engineering; ; Graduate School of Sciences and Engineering; College of Engineering; Communications Research and Innovation Laboratory (CoreLab)Orthogonal time frequency space (OTFS) is a novel waveform that provides a superior performance in doubly-dispersive channels. Since it spreads information symbols across the entire delay-Doppler plane, OTFS can achieve full diversity. However, reliability still needs to be improved in OTFS systems to meet the stringent demands of future communication systems. To address this issue, we propose an autoencoder (AE)-based enhanced OTFS (AEE-OTFS) modulation scheme. By training an AE under an additive white Gaussian noise (AWGN) channel, a feasible mapper and demapper are learned to improve the error performance and decrease the detection complexity of the OTFS system. The learned mapper is used to map incoming bits into high-dimensional symbols while the learned demapper recovers the information bits in the delay-Doppler domain. Additionally, we derive a theoretical upper bound for the frame error rate (FER). Simulation results confirm that AEE-OTFS outperforms conventional OTFS in terms of FER under perfect and imperfect channel conditions. AEE-OTFS also enjoys low decoding complexity in addition to its superior error performance.