2 citations · 4 across the 31 of their papers we have counts for
31 papers
Green Cell-Free Massive MIMO for ISAC: Joint Cloud, Fronthaul and Radio Resource Allocation
Zinat Behdad, Özlem Tuğfe Demir, Ki Won Sung +2
In this paper, we develop a cross-layer end-to-end (E2E) resource orchestration framework for green cell-free massive multiple-input multiple-output (CF-mMIMO) integrated sensing a…
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…
Distributed Two-Phase Processing for Modular XL-MIMO with Wireless Fronthaul under Hardware Impairments
Özlem Tuğfe Demir
Modular extremely large-scale MIMO (XL-MIMO) architectures combined with wireless fronthaul provide a scalable alternative to monolithic arrays, but their performance is sensitive…
Constant-Envelope Quantized Precoding with Power Control for Cell-Free Massive MIMO-OFDM
Özlem Tuğfe Demir, Salih Gümüşbuğa
Cell-free massive MIMO has matured into a key candidate technology for 6G and beyond, owing to its ability to provide nearly uniform service quality to many user equipments (UEs) o…
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…
Network-Controlled Repeaters Under Power Amplifier Non-linearities
Özlem Tuğfe Demir, Emil Björnson
Network-controlled repeaters (NCRs) are a low-cost means to extend coverage and strengthen macro diversity in wireless networks. They operate in real time by amplifying and re-tran…
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…
Cell-Free Massive MIMO with Hardware-Impaired Wireless Fronthaul
Özlem Tuğfe Demir, Emil Björnson
Cell-free massive MIMO (multiple-input multiple-output) enhances spectral and energy efficiency compared to conventional cellular networks by enabling joint transmission and recept…
From Antenna Abundance to Antenna Intelligence in 6G Gigantic MIMO Systems
Emil Björnson, Amna Irshad, Özlem Tugfe Demir +3
Current cellular systems achieve high spectral efficiency through Massive MIMO, which leverages an abundance of antennas to create favorable propagation conditions for multiuser sp…
Joint Impact of ADC and Fronthaul Quantization in Cell-Free Massive MIMO-OFDM Uplink
Özlem Tuğfe Demir, Emil Björnson
In the uplink of a cell-free massive MIMO system, quantization affects performance in two key domains: the time-domain distortion introduced by finite-resolution analog-to-digital…
Hardware Distortion Aware Precoding for ISAC Systems
Murat Babek Salman, Emil Björnson, Özlem Tugfe Demir
The impact of hardware impairments on the spectral efficiency of communication systems is well studied, but their effect on sensing performance remains unexplored. In this paper, w…
Near-Field Channel Estimation with ELAA Modular Arrays Under Hardware Impairments
Özlem Tuğfe Demir, Emil Björnson
Extremely large-scale antenna arrays (ELAAs) enable high spatial resolution and multiplexing, especially for user equipments (UEs) in the radiative near-field. To reduce hardware c…
Comprehensive Analysis of Behavioral Hardware Impairments in Cell-Free Massive MIMO-OFDM Uplink: Centralized Operation
Özlem Tuğfe Demir, Muhammed Selman Somuncu, Ahmet M. Elbir +1
Cell-free massive MIMO is a key 6G technology, offering superior spectral and energy efficiency. However, its dense deployment of low-cost access points (APs) makes hardware impair…
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…
RIS-Assisted Survivable Fronthaul Design in Cell-Free Massive MIMO System
Zhenyu Li, Özlem Tuğfe Demir, Emil Björnson +1
This paper investigates the application of reconfigurable intelligent surfaces (RISs) to improve fronthaul link survivability in cell-free massive MIMO (CF mMIMO) systems. To enhan…
Millimeter-Wave Joint Radar and Communications With an RIS-Integrated Array
Steven Rivetti, Ozlem Tugfe Demir, Emil Bjornson +1
In the context of the joint radar and communications (JRC) framework, reconfigurable intelligent surfaces (RISs) emerged as a promising technology for their ability to shape the pr…
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…
Predictive Beamforming with Distributed MIMO
Hasret Taha Akçalı, Özlem Tuğfe Demir, Tolga Girici +1
In vehicle-to-everything (V2X) applications, roadside units (RSUs) can be tasked with both sensing and communication functions to enable sensing-assisted communications. Recent stu…
Achieving Beamfocusing via Two Separated Uniform Linear Arrays
Alva Kosasih, Özlem Tugfe Demir, Emil Björnson
This paper investigates coordinated beamforming using a modular linear array (MLA), composed of a pair of physically separated uniform linear arrays (ULAs), treated as sub-arrays.…
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…
Capacity Maximization for MIMO Channels Assisted by Beyond-Diagonal RIS
Emil Björnson, Özlem Tuğfe Demir
Reconfigurable intelligent surfaces (RISs) can improve the capacity of wireless communication links by passively beamforming the impinging signals in desired directions. This featu…
Clutter-Aware Target Detection for ISAC in a Millimeter-Wave Cell-Free Massive MIMO System
Steven Rivetti, Ozlem Tugfe Demir, Emil Bjornson +1
In this paper, we investigate the performance of an integrated sensing and communication (ISAC) system within a cell-free massive multiple-input multiple-output (MIMO) system. Each…