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Indexed at: search.filters.indexed.ScopusSubject: search.filters.subject.Energy transfer

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Now showing 1 - 4 of 4
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    PublicationOpen Access
    Minimum length scheduling for discrete rate based full duplex wireless powered communication networks
    (Springer, 2019) Sadi, Yalçın; Department of Electrical and Electronics Engineering; Ergen, Sinem Çöleri; Iqbal, Muhammad Shahid; Faculty Member; PhD Student; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; 7211; N/A
    In this study, we consider a wireless powered communication network where multiple users with radio frequency energy harvesting capabilities communicate to a hybrid energy and information access point in full duplex mode. We characterize an optimization framework for minimum length scheduling to determine the optimal rate adaptation and transmission scheduling subject to energy causality and traffic demand constraints of the users considering discrete-rate transmission model. We first formulate the problem as a mixed integer nonlinear programming problem which is hard to solve for a global optimum in polynomial-time. Then, based on an analysis on the characteristics of the optimal solution, we derive optimality conditions for rate adaptation and scheduling using which we propose a fast polynomial-time complexity heuristic algorithm. We illustrate through numerical analysis that the proposed algorithm performs very close to optimal for various network scenarios.
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    PublicationOpen Access
    Minimum length scheduling for power constrained harvest-then-transmit communication networks
    (Institute of Electrical and Electronics Engineers (IEEE), 2019) Department of Electrical and Electronics Engineering; Ergen, Sinem Çöleri; Salık, Elif Dilek; Önalan, Aysun Gurur; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; 7211; N/A; N/A
    We consider a wireless powered, harvest-then-transmit communication network, which consists of a single antenna, energy and information access point (AP) and multiple, single antenna, batteryless users with energy harvesting capabilities. At the beginning of a time frame, the AP broadcasts energy in the downlink to the users. Then, users transmit their data to the AP in the uplink, using their harvested energy. We formulate the optimization problem with the objective of minimizing the total schedule length, subject to the constraints on the minimum amount of data to be sent to the AP, and unlike previous studies, the maximum transmit power for the information transmission. This problem is nonlinear and non-convex. The solution is based on bi-level optimization, consisting of optimizing the transmit power allocation of the nodes for a given energy harvesting time and searching over harvesting time allocation. We also propose a heuristic algorithm in which we incorporate the optimal solution of a single user network. Simulation results demonstrate that under appropriate network conditions, our proposed algorithms provide close-to-optimal results with a reasonable run time compared to a previously proposed time minimization algorithm that does not integrate the uplink power constraint.
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    PublicationOpen Access
    Optimal power control and scheduling for energy harvesting wireless networked control systems
    (Institute of Electrical and Electronics Engineers (IEEE), 2019) Department of Electrical and Electronics Engineering; Ergen, Sinem Çöleri; Karadağ, Göksu; Faculty Member; Undergraduate Student; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; 7211; N/A
    In this paper, we introduce RF energy harvesting paradigm into WNCS framework to study the optimal power control, energy harvesting and scheduling problem with the objective of providing maximum level of adaptivity under strict timing and reliability requirements employing the constant rate transmission model. We formulate the problem as a Mixed Integer Linear Programming Problem (MILP). We show the power allocation can be separated from the scheduling and harvesting at optimality. Then, we introduce a heuristic algorithm for the scheduling problem, periodic list scheduling (PLS), inspired from list scheduling of jobs with sequence dependent setup times on identical machines. We then demonstrate via extensive simulations the superiority of the proposed algorithm in terms of closeness to the optimal, adaptivity and runtime.
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    PublicationOpen Access
    Simulation of bulk piezoelectric implant with amplitude modulation-based backscatter communication for implant applications
    (Institute of Electrical and Electronics Engineers (IEEE), 2021) Akhtar M.J., Toymus A.T., Beker L.; Department of Mechanical Engineering; Department of Electrical and Electronics Engineering; Toymus, Alp Timuçin; Akhtar, Muhammad Junaid; Beker, Levent; Faculty Member; Department of Mechanical Engineering; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; N/A; N/A; 308798
    Recently, ultrasound has been used for power transfer and backward data transmission from implantable medical devices. Backward data communication is typically based on the amplitude modulation of the backscattered signal with changing electrical load of the implant. Contrary to its importance, the sensitivity of the backscattered voltage with reference to the electrical load has not been quantitatively determined yet. This work presents the results of transient simulations and shows the increasing trend in echo voltage with the increasing load resistance. Additionally, simulation studies indicate a decreasing sensitivity of echo voltage to load resistance with increasing backing impedance of the implant.