11 citations · 17 across the 24 of their papers we have counts for
24 papers
Joint Access and Fronthaul Resource Allocation for Cell-Free Massive MIMO with Wireless Fronthaul
Ozan Alp Topal, Özlem Tuğfe Demir, Emil Björnson +1
Wireless fronthaul is a key enabler of flexible and scalable cell-free massive MIMO systems, but its limited capacity poses significant challenges for maintaining high and uniform…
Rethinking Energy Efficiency in Cell-Free Massive MIMO: The Role of Processing and Optical Fronthaul
Ozan Alp Topal, Özlem Tuğfe Demir, Cicek Cavdar
Cell-free massive MIMO promises uniformly high performance by combining densely distributed radio units, coherent transmission, and centralized processing. Unlike earlier radio gen…
Capacity Analysis of OFDM Systems with a Swarm of Network-Controlled Repeaters
Doğa Evgür, Ozan Alp Topal, Özlem Tuğfe Demir
This paper investigates the uplink capacity of single-input single-output (SISO) systems assisted by a swarm of network-controlled repeaters (NCRs). We develop a rigorous wideband…
Energy Saving for Cell-Free Massive MIMO Networks: A Multi-Agent Deep Reinforcement Learning Approach
Qichen Wang, Keyu Li, Ozan Alp Topal +3
This paper focuses on energy savings in downlink operation of cell-free massive MIMO (CF mMIMO) networks under dynamic traffic conditions. We propose a multi-agent deep reinforceme…
Unlocking the Energy-Saving Potential in O-RAN Cell-Free Massive MIMO by Joint Orchestration of Radio, Wireless Fronthaul, and Cloud Resources
Ozan Alp Topal, Özlem Tuğfe Demir, Emil Björnson +1
Network virtualization and cloudification in Open Radio Access Networks (O-RAN) enable joint orchestration of the processing and fronthaul resources, which are essential for realiz…
NCR vs. Passive/Active RIS: How Much NCR Amplification is Required to Beat RIS?
Özlem Tuğfe Demir, Ozan Alp Topal, Cicek Cavdar +1
This paper investigates the fundamental tradeoff between reconfigurable intelligent surfaces (RISs) and network-controlled repeaters (NCRs) in terms of achievable signal-to-noise r…
EARL: Energy-Aware Adaptive Antenna Control with Reinforcement Learning in O-RAN Cell-Free Massive MIMO Networks
Zilin Ge, Ozan Alp Topal, Irshad Ahmad Meer +2
Cell-free massive multi-input multi-output (MIMO) promises uniform high performance across the network, but also brings a high energy cost due to joint transmission from distribute…
Cell-free ISAC for Drone Detection Considering Coverage and Age of Sensing
Zinat Behdad, Ozan Alp Topal, Cicek Cavdar
The growing presence of unauthorized drones poses significant threats to public safety, underscoring the need for aerial surveillance solutions. This work proposes a cell-free inte…
Green One-Bit Quantized Precoding in Cell-Free Massive MIMO
Salih Gümüsbuğa, Ozan Alp Topal, Özlem Tuğfe Demir
Cell-free massive MIMO (multiple-input multiple-output) is expected to be one of the key technologies in sixth-generation (6G) and beyond wireless communications, offering enhanced…
Fair and Energy-Efficient Activation Control Mechanisms for Repeater-Assisted Massive MIMO
Ozan Alp Topal, Özlem Tuğfe Demir, Emil Björnson +1
Massive multiple-input multiple-output (mMIMO) has been the core of 5G due to its ability to improve spectral efficiency and spatial multiplexing significantly; however, cell-edge…
UAV-Based Cell-Free Massive MIMO: Joint Placement and Power Optimization under Fronthaul Capacity Limitations
Neetu R. R, Ozan Alp Topal, Özlem Tuğfe Demir +4
We consider a cell-free massive multiple-input multiple-output (mMIMO) network, where unmanned aerial vehicles (UAVs) equipped with multiple antennas serve as distributed UAV-acces…
Detecting Unauthorized Drones with Cell-Free Integrated Sensing and Communication
Xinyue Li, Zinat Behdad, Ozan Alp Topal +2
Integrated sensing and communication (ISAC) boosts network efficiency by using existing resources for diverse sensing applications. In this work, we propose a cell-free massive MIM…
Energy-Efficient Cell-Free Massive MIMO with Wireless Fronthaul
Ozan Alp Topal, Özlem Tuğfe Demir, Emil Björnson +1
Cell-free massive MIMO improves the fairness among the user equipments (UEs) in the network by distributing many cooperating access points (APs) around the region while connecting…
Communicate or Sense? AP Mode Selection in mmWave Cell-Free Massive MIMO-ISAC
Weixian Yan, Ozan Alp Topal, Zinat Behdad +2
Integrated sensing and communication (ISAC) is a promising technology for future mobile networks, enabling sensing applications to be performed by existing communication networks,…
Self-Sustainable Metasurface-Assisted mmWave Indoor Communication System
Zhenyu Li, Ozan Alp Topal, Özlem Tuğfe Demir +2
In the design of a metasurface-assisted system for indoor environments, it is essential to take into account not only the performance gains and coverage extension provided by the m…
Mixed Static and Reconfigurable Metasurface Deployment in Indoor Dense Spaces: How Much Reconfigurability is Needed?
Zhenyu Li, Ozan Alp Topal, Özlem Tuğfe Demir +2
In this paper, we investigate how metasurfaces can be deployed to deliver high data rates in a millimeter-wave (mmWave) indoor dense space with many blocking objects. These surface…
mmWave Coverage Extension Using Reconfigurable Intelligent Surfaces in Indoor Dense Spaces
Zhenyu Li, Ozan Alp Topal, Özlem Tuğfe Demir +2
In this work, we consider the deployment of reconfigurable intelligent surfaces (RISs) to extend the coverage of a millimeter-wave (mmWave) network in indoor dense spaces. We first…
mmWave Communications for Indoor Dense Spaces: Ray-Tracing Based Channel Characterization and Performance Comparison
Ozan Alp Topal, Mustafa Ozger, Dominic Schupke +2
In this paper, the indoor dense space (IDS) channel at 28 GHz is characterized through extensive Ray-Tracing (RT) simulations. We consider IDS as a specific type of indoor environm…
Physical Layer Authentication for LEO Satellite Constellations
Ozan Alp Topal, Gunes Karabulut Kurt
Physical layer authentication (PLA) is the process of claiming identity of a node based on its physical layer characteristics such as channel fading or hardware imperfections. In t…
Securing the Inter-Spacecraft Links: Physical Layer Key Generation from Doppler Frequency Shift
Ozan Alp Topal, Gunes Karabulut Kurt, Halim Yanikomeroglu
In this work, we propose a secret key generation procedure specifically designed for the inter-spacecraft communication links. As a novel secrecy source, the spacecrafts utilize Do…
An Adaptive Multi-Agent Physical Layer Security Framework for Cognitive Cyber-Physical Systems
Mehmet Özgün Demir, Ozan Alp Topal, Ali Emre Pusane +3
Being capable of sensing and behavioral adaptation in line with their changing environments, cognitive cyber-physical systems (CCPSs) are the new form of applications in future wir…
Securing the Inter-Spacecraft Links: Doppler Frequency Shift based Physical Layer Key Generation
Ozan Alp Topal, Gunes Karabulut Kurt, Halim Yanikomeroglu
We propose a novel physical layer secret key generation method for the inter-spacecraft communication links. By exploiting the Doppler frequency shifts of the reciprocal spacecraft…
A Polynomial Interpolation based Quantum Key Reconciliation Protocol: Error Correction without Information Leakage
Gunes Karabulut Kurt, Enver Ozdemir, Neslihan Aysen Ozkirisci +2
In this work, we propose a novel key reconciliation protocol for the quantum key distribution (QKD). Based on Newton's polynomial interpolation, the proposed protocol aims to corre…
Identification of Smart Jammers: Learning based Approaches Using Wavelet Representation
Ozan Alp Topal, Selen Gecgel, Ender Mete Eksioglu +1
Smart jammer nodes can disrupt communication between a transmitter and a receiver in a wireless network, and they leave traces that are undetectable to classical jammer identificat…