Organizational Unit: Electrical & Electronics Engineering
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Conference ObjectPublication Metadata only LIG at MediaEval 2015 multimodal person discovery in broadcast TV task(CEUR-WS, 2015) Budnik, M.; Safadi, B.; Besacier, L.; Quénot, G.; Khodabakhsh, Ali; Demiroğlu, Cenk; Electrical & Electronics Engineering; DEMİROĞLU, Cenk; Khodabakhsh, AliIn this working notes paper the contribution of the LIG team (partnership between Univ. Grenoble Alpes and Ozyegin University) to the Multimodal Person Discovery in Broadcast TV task in MediaEval 2015 is presented. The task focused on unsupervised learning techniques. Two different approaches were submitted by the team. In the first one, new features for face and speech modalities were tested. In the second one, an alternative way to calculate the distance between face tracks and speech segments is presented. It also had a competitive MAP score and was able to beat the baseline.Conference ObjectPublication Metadata only Recovery of temporal synchronization error through online 3D tracking with two cameras(ACM, 2014) Topçu, O.; Ercan, Ali Özer; Alatan, A. A.; Electrical & Electronics Engineering; ERCAN, Ali ÖzerMultiple object tracking within a network of cameras with overlapping fields of views has gained interest. The acquisition of images in an asynchronous manner hinders the practical implementation of such systems. Most of the previous work reported tests over short intervals, leaving the performance degradation due to asynchronous image acquisition unknown. In this work, we propose an online method to recover the synchronization error while tracking objects. The recovered error is fed back to trackers so as to restore their performance. The time synchronization error is measured by the mismatch in the epipolar constraint between the two cameras. We show that successful recovery of the synchronization error is possible when its product with the object motion speeds are within some limits.Conference ObjectPublication Metadata only Outage performance of multi-hop hybrid FSO/RF communication systems(IEEE, 2015) Kazemi, H.; Uysal, Murat; Touati, F.; Haas, H.; Electrical & Electronics Engineering; UYSAL, MuratIn this paper, five scenarios are considered for the realization of a multi-hop hybrid free-space optical/radio frequency (FSO/RF) communication system with decode-and-forward (DF) relaying, and analytical outage probability expressions are derived. The scenarios have a different number of FSO and RF links. The aim is to identify an optimum scenario to effectively improve the end-to-end reliability of the multi-hop hybrid FSO/RF system. Outage performance is investigated for the scenarios under various weather conditions through numerical examples. It is identified that for a given link distance the end-to-end outage probability is minimized when using a hybrid FSO/RF link between every two successive nodes of the multi-hop system, and this requires the maximum number of FSO and RF links to be deployed.Conference ObjectPublication Metadata only Performance analysis of cooperative diversity networks with imperfect channel estimation over Rician fading channels(IEEE, 2010) Ikki, S. S.; Feteiha, M.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, MuratIn this paper, we examine the effect of channel estimation error on the error and outage probabilities of a multi-relay system with amplify-and-forward relaying over frequency-flat Rician fading channel. We consider orthogonal relaying and study both conventional cooperative systems (i.e., all relays participate in the relaying phase) and opportunistic cooperative systems (i.e., only the best relay participates in the relaying phase). Based on the derivation of effective signal-to-ratio (SNR) at the receiver taking into account channel estimation error, we obtain closed-form expressions for error and outage probabilities in high SNR regime. Such closed form solutions are highly desirable because they allow for rapid and efficient evaluation of system performance. Computer simulations are used to validate our analytical results.ArticlePublication Metadata only Defect-aware nanocrossbar logic mapping through matrix canonization using two-dimensional radix sort(ACM, 2011-08) Gören, S.; Uğurdağ, Hasan Fatih; Palaz, O.; Electrical & Electronics Engineering; UĞURDAĞ, Hasan FatihNanocrossbars (i.e., nanowire crossbars) offer extreme logic densities but come with very high defect rates; stuck-open/closed, broken nanowires. Achieving reasonable yield and utilization requires logic mapping that is defect-aware even at the crosspoint level. Such logic mapping works with a defect map per each manufactured chip. The problem can be expressed as matching of two bipartite graphs; one for the logic to be implemented and other for the nanocrossbar. This article shows that the problem becomes a Bipartite SubGraph Isomorphism (BSGI) problem within sub-nanocrossbars free of stuck-closed faults. Our heuristic KNS-2DS is an iterative rough canonizer with approximately O(N2) complexity followed by an O(N3) matching algorithm. Canonization brings a partial or full order to graph nodes. It is normally used for solving the regular Graph Isomorphism (GI) problem, while we apply it to BSGI. KNS stands for K-Neighbor Sort and is used for initializing our main contribution 2-Dimensional-Sort (2DS). 2DS operates on the adjacency matrix of a bipartite graph. Radix-2 2DS solves the problem in the absence of stuck-closed faults. With the addition of Radix-3 and our novel Radix-2.5 sort, we solve problems that also have stuck-closed faults. We offer very short runtimes (due to canonization) compared to previous work and have success on all benchmarks. KNS-2DS is also novel from the perspective of BSGI problem as it is based on canonization but not on a search tree with backtracking.Conference ObjectPublication Metadata only Digital data integration project between a DSO and a university for sustainability and efficiency(IEEE, 2022) Kartcı, Emin; Akkus, E. E.; Sancar, Semanur; Bugdayci, T. A.; Bektas, M.; Poyrazoğlu, Göktürk; Electrical & Electronics Engineering; POYRAZOĞLU, Göktürk; Kartcı, Emin; Sancar, SemanurDigitization in the energy sector enables big data analysis that can lead to large-scale energy efficiency due to the size of the sector and thus getting closer to sustainability targets. With a digital data integration study between a distribution company and a university in Turkey for big data processing, the data collected by IoT devices from 6,000 active transformers providing service in 5 cities were transferred to different servers together with the developed communication protocols. As a result of the project, the transformer efficiency and sustainability measures were produced. In this study, the mutually established software infrastructure and the benefits of the project are explained.Conference ObjectPublication Metadata only Non-orthogonal multiple access (NOMA) for indoor visible light communications(IEEE, 2015) Kizilirmak, R. C.; Rowel, C. R.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, MuratProviding multiple access support to visible light communication (VLC) systems requires new networking architecture. Non-orthogonal multiple access (NOMA) is a proposed multiple access technique for future cellular systems. In this work, based on a realistic indoor channel conditions, we apply NOMA to indoor VLC channels and demonstrate its superior performance over orthogonal frequency division multiple access (OFDMA).Conference ObjectPublication Metadata only Broadcasting brake lights with MIMO-OFDM based vehicular VLC(IEEE, 2016) Turan, B.; Narmanlıoğlu, Ömer; Coleri Ergen, S.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Narmanlıoğlu, ÖmerInter-vehicular connectivity to enhance road safety and enable highly autonomous driving is increasingly becoming popular. Despite the prevalent works on radio-frequency (RF) based vehicular communication schemes, visible light communication (VLC) is considered to be a promising candidate for vehicular communications due to its low complexity and RF interference-free nature. This paper investigates applicability of VLC to enhance road safety based on real world measurements. Deployment of multiple light emitting diodes (LEDs) enables multiple-input multiple-output (MIMO) transmission in the context of vehicular VLC. We consider direct current biased optical orthogonal frequency division multiplexing (DCO-OFDM) based MIMO transmission scheme and evaluate the performances of different MIMO modes including repetition code (RC) and spatial multiplexing (SM), different modulation orders and different transmitter-receiver selection. The results reveal that selection of the closest transmitters to the receivers, provide better performance due to high signal-to-noise-ratio (SNR) requirements for RC mode. However, usage of all possible transmitters does not always yield better performance due to power division at the transmitter side. Moreover, SM suffers from channel correlation whereas the performance of RC shows more degradation on higher-order modulations that are required to yield the same throughput with SM.ArticlePublication Metadata only Fast two-pick n2n round-robin arbiter circuit(IEEE, 2012-06) Uğurdağ, Hasan Fatih; Temizkan, Fatih; Baskirt, O.; Yuce, B.; Electrical & Electronics Engineering; UĞURDAĞ, Hasan Fatih; Temizkan, FatihA regular (one-pick) round-robin arbiter circuit picks one active requester (if any) out of n requesters. A two-pick round-robin arbiter selects up to two requesters. An n2n two-pick round-robin arbiter indicates the picked requests with (at most) two-hot n-bit output. A round-robin arbiter is fair to its requesters and does this by repeatedly moving its highest priority pointer to the position immediately next to the second requester picked. Presented is the circuit architecture and VLSI implementation of a new scalable two-pick round-robin arbiter with low latency, which is compared with previous work based on logic synthesis results.ArticlePublication Metadata only A comparative evaluation of propagation characteristics of vehicular VLC and MMW channels(IEEE, 2023) Hosseinabadi, Fahimeh Aghaei; Eldeeb, H. B.; Uysal, Murat; Electrical & Electronics Engineering; UYSAL, Murat; Hosseinabadi, Fahimeh AghaeiVehicle-to-vehicle (V2V) communication is an underlying key technology to realize future intelligent transportation systems. Both millimeter wave (MMW) communication and visible light communication (VLC) are strong candidates to address V2V connectivity. Most of the earlier literature focuses on an individual technology. In an effort to better highlight the differences and relative advantages of these two competing technologies, we provide a comprehensive one-to-one comparison between vehicular VLC and MMW channels in this paper. For this purpose, we utilize ray tracing simulations which enable the consideration of three-dimensional modeling of the propagation environment and allow the study of various system parameters and road conditions in both line-of-sight and non-line-of-sight conditions. Under the same settings, we present the received signal strengths for both systems and investigate the channel characteristics for communication between two vehicles in the same lane as well as in different lanes with a lateral shift. We also analyze the impact of low, medium, and high density of neighbor vehicles as well as partial and complete blockage.