Browsing by Subject "Visible light positioning"

Now showing 1 - 3 of 3

Open Access
Optimal and robust power allocation for visible light positioning systems under illumination constraints
(IEEE, 2019-01) Keskin, Musa Furkan; Sezer, Ahmet Dündar; Gezici, Sinan
The problem of optimal power allocation among light emitting diode (LED) transmitters in a visible light positioning system is considered for the purpose of improving localization performance of visible light communication (VLC) receivers. Specifically, the aim is to minimize the Cramér-Rao lower bound (CRLB) on the localization error of a VLC receiver by optimizing LED transmission powers in the presence of practical constraints, such as individual and total power limitations and illuminance constraints. The formulated optimization problem is shown to be convex and thus can efficiently be solved via standard tools. We also investigate the case of imperfect knowledge of localization parameters and develop robust power allocation algorithms by taking into account both overall system uncertainty and individual parameter uncertainties related to the location and orientation of the VLC receiver. In addition, we address the total power minimization problem under predefined accuracy requirements to obtain the most energy-efficient power allocation vector for a given CRLB level. Numerical results illustrate the improvements in localization performance achieved by employing the proposed optimal and robust power allocation strategies over the conventional uniform and non-robust approaches.
Open Access
Optimal pulse design for visible light positioning systems
(Elsevier BV, 2021-10-16) Yazar, Onurcan; Gezici, Sinan
The problem of optimal pulse design for light-emitting diode (LED) transmitters is investigated in an indoor visible light positioning (VLP) setup. In particular, the problem of localization performance maximization is formulated for both asynchronous and synchronous VLP systems with consideration of practical limitations related to power consumption, illumination levels, and/or effective bandwidths, while quantifying the localization accuracy via the Cramér–Rao lower bound (CRLB). In both asynchronous and synchronous scenarios, the formulated problems are shown to be convex optimization problems, and some properties of the optimal solutions are derived. In addition, the pulse design problem for minimum power consumption is formulated under a CRLB constraint along with other practical limitations; and this problem is also revealed to be a convex optimization problem. Based on the solutions of the proposed optimization problems, pulse design procedures are described to determine the parameters of optimal pulse shapes. Numerical results illustrate the benefits of the proposed optimal pulse design approach in comparison with the state-of-the-art optimal power allocation scheme in the literature. In particular, electrical power consumption can be reduced by around 45% or localization accuracy can be improved by as much as 25% via the proposed optimal pulse design approach in certain scenarios.
Open Access
Optimal signal design for visible light positioning under power and illumination constraints
(2021-11) Yazar, Onurcan
The optimal design of transmit signals for light-emitting diodes (LEDs) in a visible light positioning (VLP) system is analyzed with the objectives of im-provements in localization accuracy and power eﬃciency. Speciﬁcally, the lo-calization performance maximization problem is addressed for asynchronous and synchronous VLP systems where certain system limitations including power con-sumption, illumination, and eﬀective bandwidth are considered, and the localiza-tion performance is quantiﬁed using the Cram´er-Rao lower bound (CRLB). The formulated signal design problems are demonstrated to be convex optimization problems and some properties of the optimal signal design parameters are found. On the other hand, the signal design problem is also formulated for achieving the lowest possible power consumption while guaranteeing a certain localization ac-curacy. Then, the optimal signal design parameters resulted from the solution of these optimization problems are used to construct the optimal transmit signals in the LEDs. The advantages of the optimal signal design approach is demonstrated through the numerical experiments while also presenting a comparison with the state-of-the-art optimal power allocation method in the literature.