GCRIS Repository Collection: Collection of Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği Bölümü koleksiyonu
Collection of Electrical - Electronic Engineering / Elektrik - Elektronik Mühendisliği Bölümü koleksiyonu
https://hdl.handle.net/11147/11
2024-03-25T10:36:06Z
2024-03-25T10:36:06Z
Liquid metal-controlled dual-band doppler radar for enhanced velocity measurement
Karatay, Anıl
Yaman, Fatih
https://hdl.handle.net/11147/14245
2024-02-12T12:16:49Z
2024-01-01T00:00:00Z
Title: Liquid metal-controlled dual-band doppler radar for enhanced velocity measurement
Authors: Karatay, Anıl; Yaman, Fatih
Abstract: Doppler radars, which are critical instruments for velocity measurement, may need to be reconfigured to adapt to different environmental conditions or for ease of use. However, conventional electrical, optical, and physical reconfiguration methods often come with several disadvantages such as deteriorated radiation pattern, reduced radiation efficiency, and high cost. Therefore, the aim of this article is to integrate microwave components that can be controlled using liquid metal (LM) displacement into a Doppler radar to adjust its main lobe direction and operating frequency to the desired values and enhance the measurement capacity of the respective radar. Through this study, multiple parameters of an operational Doppler radar have been simultaneously adjusted using LM displacement exploitation for the first time, thus avoiding the shortcomings associated with conventional reconfiguration methods. To achieve this objective, initially, a back-to-back Vivaldi antenna operating at 2.45 GHz is designed, and beam switching ability is imparted to the structure using the LM displacement method. Subsequently, various techniques are used to convert the structure into a dual-band antenna capable of simultaneous operation at 2.45 and 5.8 GHz, ensuring the desired beam switching feature at both the frequencies. In addition, a power divider capable of switching between the two operating frequencies through LM assistance is proposed, and its integration into the radar system enables the control of both main lobe direction and frequency using the proposed method.
2024-01-01T00:00:00Z
Carrier frequency offset based shared randomness for secure transmission in M-PSK NOMA
Göztepe, Caner
Karabulut Kurt, Güneş
Özbek, Berna
https://hdl.handle.net/11147/14153
2024-01-22T13:13:35Z
2023-01-01T00:00:00Z
Title: Carrier frequency offset based shared randomness for secure transmission in M-PSK NOMA
Authors: Göztepe, Caner; Karabulut Kurt, Güneş; Özbek, Berna
Abstract: Power domain non-orthogonal multiple access (NOMA) enhances spectral efficiency by superposing multiple users in the same time-frequency resource block at the expense of exposing the users' data. However, current approaches to improve the secrecy levels of users are limited to rate reduction. This paper proposes a secure NOMA system based on the shared randomness extracted from the reciprocal carrier frequency offsets (CFOs) between the transmitter-receiver pairs for M-ary phase-shift keying. As multiple users will have physically separated oscillators, it will result in independent CFOs among users. This randomness is used to introduce a constellation rotation in the transmitted symbols. We show that under ideal CFO estimates, the proposed approach achieves perfect secrecy among all NOMA users without introducing any rate reduction. We also demonstrate the practical applicability of the proposed approach by using a software-defined radio-based test bed. © 2023 IEEE.
Description: IEEE Communications Society; 2023 IEEE International Black Sea Conference on Communications and Networking, BlackSeaCom 2023 -- 4 July 2023 through 7 July 2023
2023-01-01T00:00:00Z
Detection scheme for PNC-based cell-free MIMO systems
Cumalı, İrem
Özbek, Berna
Karabulut Kurt, Güneş
https://hdl.handle.net/11147/14032
2023-11-16T13:46:41Z
2023-01-01T00:00:00Z
Title: Detection scheme for PNC-based cell-free MIMO systems
Authors: Cumalı, İrem; Özbek, Berna; Karabulut Kurt, Güneş
Abstract: Cell-free multiple-input multiple-output (cell-free MIMO) is a promising concept to overcome inter-cell interference and avoid non-uniform data rates among users by combining the best features of ultra-dense networks and MIMO. Hence, cell-free MIMO can fulfill the increasing demand on data rate with uniformly good coverage for the sixth-generation (6G) wireless communications. In addition to that, physical-layer network coding (PNC) reduces the transmission delay since it requires only two time slots instead of four time slots to exchange information between two users. In this paper, we propose a novel scheme called PNC-based cell-free MIMO to improve reliability further while reducing the transmission delay. We demonstrate the effectiveness of the proposed scheme regarding the bit error rate in different system configurations. The proposed PNC-based cell-free MIMO achieves significantly lower error probability than the conventional cell-free MIMO. © 2023 IEEE.
Description: 3rd IEEE International Mediterranean Conference on Communications and Networking, MeditCom 2023 -- 4 September 2023 through 7 September 2023
2023-01-01T00:00:00Z
Compact proton accelerator in UHF band at KAHVELab
Esen, S.
Adıgüzel, A.
Koçer, O.
Çağlar, A.
Çelebi, E.
Öz, S.
Özcan, V.E.
Karatay, Anıl
Yaman, Fatih
Yılmaz, Hasan Önder
https://hdl.handle.net/11147/14003
2023-11-15T13:36:36Z
2022-01-01T00:00:00Z
Title: Compact proton accelerator in UHF band at KAHVELab
Authors: Esen, S.; Adıgüzel, A.; Koçer, O.; Çağlar, A.; Çelebi, E.; Öz, S.; Özcan, V.E.; Karatay, Anıl; Yaman, Fatih; Yılmaz, Hasan Önder
Abstract: Proton Test Beam at KAHVELab (Kandilli Detector, Accelerator and Instrumentation Laboratory) project aims to design and produce a radio frequency quadrupole (RFQ) operating at 800 MHz in Istanbul, Turkey using the local resources. The beamline consists of a proton source, a low energy beam transport (LEBT) line including the beam diagnostic section and the RFQ cavity itself. This RFQ is 4-vane, 1-meter-long cavity to accelerate the 20 keV beam extracted from plasma ion source to 2 MeV. Its engineering prototype is already produced and subjected to mechanical, low power RF and vacuum tests. In this study, the results of the first test production, especially the bead-pull test setup will be discussed. © 2022 Proceedings - Linear Accelerator Conference, LINAC. All rights reserved.
Description: 31st International Linear Accelerator Conference, LINAC 2022 -- 28 August 2022 through 2 September 2022 -- 187095
2022-01-01T00:00:00Z