Browsing by Author "Göken, Ç."

Now showing 1 - 3 of 3

Open Access
Optimal parameter encoding based on worst case fisher information under a secrecy constraint
(Institute of Electrical and Electronics Engineers Inc., 2017) Göken, Ç.; Gezici, Sinan
In this letter, optimal deterministic encoding of a uniformly distributed scalar parameter is performed in the presence of an eavesdropper. The objective is to maximize the worst case Fisher information of the parameter at the intended receiver while keeping the mean-squared error (MSE) at the eavesdropper above a certain level. The eavesdropper is modeled to employ the linear minimum MSE estimator based on the encoded version of the parameter. First, the optimal encoding function is derived when there exist no secrecy constraints. Next, to obtain the solution of the problem in the presence of the secrecy constraint, the form of the encoding function that maximizes the MSE at the eavesdropper is explicitly derived for any given level of worst case Fisher information. Then, based on this result, a low-complexity algorithm is provided to calculate the optimal encoding function for the given secrecy constraint. Finally, numerical examples are presented.
Open Access
Optimal power allocation for secure estimation of multiple parameters
(IEEE, 2021-08-11) Gürgünoğlu, Doğa; Göken, Ç.; Gezici, Sinan
Optimal power allocation for secure estimation of multiple deterministic parameters is investigated under a total power constraint. The goal is to minimize the Cramér-Rao lower bound (CRLB) at an intended receiver while keeping estimation errors at an eavesdropper above specified target levels. To that end, an optimization problem is formulated by considering measurement models involving linear transformation of the parameter vector and additive Gaussian noise. Although the proposed optimization problem is nonconvex, it is decomposed into convex sub-problems by utilizing the structure of the secrecy constraints. Then, optimal solutions to the sub-problems are characterized via optimization theoretic approaches. An algorithm utilizing that characterization is developed to obtain the optimal solution of the proposed problem.
Open Access
Robust joint transceiver design for multiuser MIMO systems with calibration errors
(Institute of Electrical and Electronics Engineers, 2022-08-11) Kazemi, Mohammad; Göken, Ç.; Duman, Tolga Mete
We consider the downlink of a multiuser multiple-input multiple-output (MIMO) system operating in the time-division duplexing (TDD) mode. In this mode, assuming reciprocity, the channel coefficients estimated during the uplink channel training are utilized by the base station (BS) in the downlink data transmission. However, due to hardware mismatches, the uplink and downlink channels are not exactly the same, and therefore, there are calibration errors, which degrade the system performance. In this paper, our goal is to provide a transceiver design which has a robust performance under imperfect channel reciprocity. To this end, we first formulate a robust joint precoder and combiner design as a stochastic minimum mean square error (MMSE) optimization problem. Then, employing an alternating optimization approach, we propose an algorithm to obtain the precoding and combining matrices assuming imperfect CSI and calibration errors at both the BS and user sides. Extensive simulation results show that the proposed robust joint precoder/combiner outperforms the existing solutions in the literature.