Oznur Ozkasap

Koc University · Department of Computer Engineering

Artificial intelligence (AI) and deep learning techniques have gained significant attraction in recent years, owing to their remarkable capability of achieving high performance across a broad range of applications. However, a crucial challenge in training such models is the acquisition of vast amounts of data, which is often limited in fields like...

Federated Learning (FL) has become a key choice for distributed machine learning. Initially focused on centralized aggregation, recent works in FL have emphasized greater decentralization to adapt to the highly heterogeneous network edge. Among these, Hierarchical, Device-to-Device and Gossip Federated Learning (HFL, D2DFL \& GFL respectively) can...

Intending to support new emerging applications with latency requirements below what can be offered by the cloud data centers, the edge and fog computing paradigms have reared. In such systems, the real-time instant data is processed closer to the edge of the network, instead of the remote data centers. With the advances in edge and fog computing sy...

Federated Learning (FL) has become a key choice for distributed machine learning. Initially focused on centralized aggregation, recent works in FL have emphasized greater decentralization to adapt to the highly heterogeneous network edge. Among these, Hierarchical, Device-to-Device and Gossip Federated Learning (HFL, D2DFL & GFL respectively) can b...

Objectives: To evaluate the effect of a symptom management mobile application on quality of life and symptom severity in women with breast cancer undergoing chemotherapy. Sample & setting: This parallel randomized pilot study consisted of women with breast cancer admitted to oncology outpatient clinics between November 2019 and January 2021 in T...

Edge intelligence has become popular recently since it brings smartness and copes with some shortcomings of conventional technologies such as cloud computing, Internet of Things (IoT), and centralized AI adoptions. However, although utilizing edge intelligence contributes to providing smart systems such as automated driving systems, smart cities, a...

Growing intelligent cities is witnessing an increasing amount of local energy generation through renewable energy resources. Energy trade among the local energy generators ( aka prosumers) and consumers can reduce the energy consumption cost and also reduce the dependency on conventional energy resources, not to mention the environmental, economic,...

Peer-to-Peer (P2P) energy trading platforms envisioned energy sectors to satisfy the increasing demand for energy. The vision of this paper is not only to trade energy but also to have part of it being shared. Therefore, this paper presents FederatedGrids which is a P2P energy trading and sharing platform inside and across microgrids. Energy shar...

In today’s modern era, with the rapid growth of edge-assisted solutions especially Internet of Things (IoT) networks, connected healthcare progressively relies on such solutions. Connected healthcare systems refer to health systems in which all the stakeholders are connected to each other. These systems employ novel technologies such as IoT, edge c...

Fog computing is suitable for latency constrained applications useful to end users and IoT devices in smart cities, factories, and homes. A federation among fogs is beneficial for subscribers and providers in terms of enhanced capability, capacity, coverage, and services. To realize such a federation, a third-party authentication mechanism among fo...

Several distributed system paradigms utilize Distributed Hash Tables (DHTs) to realize structured peer-to-peer (P2P) overlays. DHT structures arise as the most commonly used organizations for peers that can efficiently perform crucial services such as data storage, replication, query resolution, and load balancing. With the advances in various dist...

As an append-only distributed database, blockchain is utilized in a vast variety of applications including the cryptocurrency and Internet-of-Things (IoT). The existing blockchain solutions show downsides in communication and storage scalability, as well as decentralization. In this article, we propose LightChain , which is the first blockchain arc...

We study the problem of asynchronous rendezvous search with multiple mobile agents (robots) in the plane. The goal of the robots is to meet at a location in the environment which is not determined in advance as quickly as possible. They do not know the initial locations of each other or their own initial locations. Moreover, the initial distance be...

As blockchain-based systems see wider adoption, it becomes increasingly critical to ensure their reliability, security, and efficiency. Running simulations is an effective method of gaining insights on the existing systems and analyzing potential improvements. However, many of the existing blockchain simulators have various shortcomings that yield...

The demand for real-time, affordable, and efficient smart healthcare services is increasing exponentially due to the technological revolution and burst of population. To meet the increasing demands on this critical infrastructure, there is a need for intelligent methods to cope with the existing related challenges. In this regard, edge computing te...

As an append-only distributed database, blockchain is utilized in a vast variety of applications including the cryptocurrency and Internet-of-Things (IoT). The existing blockchain solutions show downsides in communication and storage scalability, as well as decentralization. In this article, we propose LightChain , which is the first blockchain a...

The demand for real-time, affordable, and efficient smart healthcare services is increasing exponentially due to the technological revolution and burst of population. To meet the increasing demands on this critical infrastructure, there is a need for intelligent methods to cope with the existing obstacles in this area. In this regard, edge computin...

As a distributed hash table (DHT) routing overlay, Skip Graph is used in a variety of peer-to-peer (P2P) systems including cloud storage. The overlay connectivity of P2P systems is negatively affected by the arrivals and departures of nodes to and from the system that is known as churn. Preserving connectivity of the overlay network (i.e., the reac...

Industrial investments into distributed energy resource technologies are increasing and playing a pivotal role in the global transactive energy, as part of a wider drive to provide a clean and stable source of energy. The management of prosumers, that consume and as well generate energy, with heterogeneous energy sources is critical for sustainable...

Information Centric Networks (ICNs) have emerged in recent years as a new networking paradigm for the next-generation Internet. The primary goal of these networks is to provide effective mechanisms for content distribution and retrieval based on in-network content caching. Several network architectures were proposed in recent years to realize this...

Skip Graphs are Distributed Hash Table (DHT)-based data structures that are immensely utilized as routing overlays in Peer-to-Peer (P2P) applications. In this demo paper, we present the software architecture of our open-source implementation of Skip Graph middleware in Java. We also present a demo scenario on configuration and constructing an overl...

Scalability and security problems with centralized architecture models in cyberphysical systems have provided opportunities for blockchain-based distributed models. A decentralized energy-trading system takes advantage of various sources and effectively coordinates the energy to ensure the optimal utilization of available resources. Three blockchai...

The potential held by the gargantuan volumes of data being generated across networks worldwide has been truly unlocked by machine learning techniques and more recently Deep Learning. The advantages offered by the latter have seen it rapidly becoming a framework of choice for various applications. However, the centralization of computational resourc...

LightChain is the first Distributed Hash Table (DHT)-based blockchain with a logarithmic asymptotic message and memory complexity. In this demo paper, we present the software architecture of our open-source implementation of LightChain, as well as a novel deployment scenario of the entire LightChain system on a single machine aiming at results repr...

SkipSim is an offline Skip Graph simulator that enables Skip Graph-based algorithms including blockchains and P2P cloud storage to be simulated while preserving their scalability and decentralized nature. To the best of our knowledge, it is the first Skip Graph simulator that provides several features for experimentation on Skip Graph-based overlay...

Skip Graphs belong to the family of Distributed Hash Table (DHT) structures that are utilized as routing overlays in various peer-to-peer applications including blockchains, cloud storage, and social networks. In a Skip Graph overlay, any misbehavior of peers during the routing of a query compromises the system functionality. Guard is the first aut...

Software Defined Networking (SDN) has eased the management and control of networks through separation of the control and data planes. Software defined data centers (SDDC) automate the management of end systems which are physical machines and virtual machines. In data centers, although there is a vast work on minimizing power consumption of physical...

Edge computing moves the computation closer to the data and the data closer to the user to overcome the high latency communication of cloud computing. Storage at the edge allows data access with high speeds that enable latency-sensitive applications in areas such as autonomous driving and smart grid. However, several distributed services are typica...

Information Centric Networks (ICNs) have emerged in recent years as a new networking paradigm for the next-generation Internet. The primary goal of these networks is to provide effective mechanisms for content distribution and retrieval based on in-network content caching. The design of different ICN architectures addressed many of the security iss...

Online Social Networks (OSNs) offer free storage and social networking services through which users can communicate personal information with one another. The personal information of the users collected by the OSN provider comes with privacy problems when being monetized for advertising purposes. To protect user privacy, existing studies propose ut...

Edge computing moves the computation closer to the data and the data closer to the user to overcome the high latency communication of cloud computing. Storage at the edge allows data access with high speeds that enable latency-sensitive applications in areas such as autonomous driving and smart grid. However, several distributed services are typica...

Scalability and security problems with centralized architecture models in cyberphysical systems have provided opportunities for blockchain-based distributed models. A decentralized energy trading system takes advantage of various sources, and effectively coordinates the energy to ensure optimal utilization of available resources. It achieves this b...

Software-defined networking (SDN) paradigm, with the flexible and logically centralized control, enables dynamically minimizing the network energy consumption by redirecting paths of packets. However, the links and switches are designed to accommodate maximum traffic volume and their power consumption is not traffic proportional. Moreover, there ex...

As a Distributed Hash Table (DHT), Skip Graph routing overlays are exploited in several peer-to-peer (P2P) services, including P2P cloud storage. The fully decentralized replication algorithms that are applicable to the Skip Graph-based P2P cloud storage fail on improving the performance of the system with respect to both the availability of replic...

Combining the capabilities of the programmability of networks by SDN and discovering patterns by machine learning are utilized in security, traffic classification, QoS prediction, and network performance and has attracted the attention of researchers. In this work, we propose HyMER: a novel hybrid machine learning framework for traffic aware energy...

As a Distributed Hash Table (DHT), Skip Graph routing overlays are exploited in several peer-to-peer (P2P) services, including P2P cloud storage. The fully decentralized replication algorithms that are applicable to the Skip Graph-based P2P cloud storage fail on improving the performance of the system with respect to both the availability of replic...

Several cloud computing applications use Replicated State Machines (RSM) to provide fault-tolerant services, ensuring consistency with consensus protocols. However, these protocols often come with a high latency cost, sometimes even forcing system designers to sacrifice consistency for availability. This latency is due, in part, to unnecessary data...

Software-defined networking (SDN) paradigm, with the flexible and logically centralized control, enables dynamically minimizing the network energy consumption by redirecting paths of packets. However, the links and switches are designed to accommodate maximum traffic volume and their power consumption is not traffic proportional. Moreover, there ex...

Software defined networking (SDN) is a rapidly growing networking paradigm in both industry and research areas, with network programmability as its powerful feature which enables propagating changes in the network easily. The logically centralized control in SDN enables dynamically minimizing the energy consumption of the links and the switches by...

As an append-only distributed database, blockchain is utilized in a vast variety of applications including the cryptocurrency and Internet-of-Things (IoT). The existing blockchain solutions have downsides in communication and storage efficiency, convergence to centralization, and consistency problems. In this paper, we propose LightChain, which is...

As a distributed hash table (DHT) routing overlay, Skip Graph is used in a variety of peer-to-peer (P2P) systems including cloud storage, social networks, and search engines. The overlay connectivity of P2P systems is negatively affected by the arrivals and departures of nodes to and from the system that is known as churn. Preserving connectivity o...

Several distributed services ranging from key‐value stores to cloud storage require fault‐tolerance and reliability features. For enabling fast recovery and seamless transition, primary‐backup replication protocols are widely used in different application settings including distributed databases, web services, and the Internet of Things. In this st...

Software Defined Networking (SDN) achieves programmability of a network through separation of the control and data planes. It enables flexibility in network management and control. Energy efficiency is one of the challenging global problems which has both economic and environmental impact. A massive amount of information is generated in the control...

Software Defined Networking (SDN) paradigm has the benefits of programmable network elements by separating the control and the forwarding planes, efficiency through optimized routing and flexibility in network management. As the energy costs contribute largely to the overall costs in networks, energy efficiency has become a significant design requi...

Software Defined Networking (SDN) achieves programmability of network elements by separating the control and the forwarding planes, and provides efficiency through optimized routing and flexibility in network management. As the energy costs contribute largely to the overall costs in networks, energy efficiency is a significant design requirement fo...

Autonomous vehicle platoon is an enhancement of autonomous behavior, where vehicles are organized into groups of close proximity through wireless communication. Platoon members mostly communicate with each other via the current dominant vehicular radio frequency (RF) technology, IEEE 802.11p. However, this technology leads security vulnerabilities...

Skip Graph is a distributed hash table (DHT) which acts as the underlying infrastructure in various P2P applications such as cloud storage and online social networks. The basic operation in Skip Graph is the search which is done in a fully decentralized manner. Any misbehavior of peers during the routing of a search query heavily degrades the syste...

As a distributed hash table (DHT), Skip Graph acts as the underlying routing infrastructure of peer-to-peer (P2P) storage systems, distributed online social networks, search engines, and other DHT-based applications. For many P2P applications, data aggregation is vital, however, it is a missing feature of Skip Graph. The traditional aggregation alg...

Software Defined Networking (SDN) is an emerging network paradigm that gains increasing attention both from academia and industry. Energy saving aspects of network protocols, being studied for different network technologies, have also recently been addressed in SDN. In this paper, we address the traffic and energy aware routing problem in SDN and p...

Energy consumption of distributed data centers costs huge amounts to the cloud service providers (CSP) each year. In order to make the services affordable for the cloud service consumers (CSC) and increase the profit for the CSP, it is essential to minimize the cooling and operational costs. In this work, we address cost optimization by taking adva...

The traditional decentralized availability-based replication algorithms suffer from high dependence on the underlying system’s churn behavior, randomness in replica selection, and the inability of maximizing the replicas availability. These drawbacks result in poor data availability especially in low available systems as well as where the churn beh...

Technology coined as the vehicular ad hoc network (VANET) is harmonizing with Intelligent Transportation System (ITS) and Intelligent Traffic System (ITF). An application scenario of VANET is the military communication where vehicles move as a convoy on roadways, requiring secure and reliable communication. However, utilization of radio frequency (...

With the prevalence of information and communication technologies, Electronic Health Services (EHS) are commonly used by patients, doctors, and other healthcare professionals to decrease healthcare costs and provide efficient healthcare processes. However, using EHS increases the concerns regarding security, privacy, and integrity of healthcare dat...

With increasing popularity of cloud storage, efficiently proving the integrity of data stored on an untrusted server has become significant. Authenticated skip lists and rank-based authenticated skip lists (RBASL) have been used to provide support for provable data update operations in cloud storage. However, in a dynamic file scenario, an RBASL ba...

Advances in auto-mobile industry and urbanization enable vehicles communicate with each other and link adjacent cities to form connected smart cities. As a result, vehicular ad-hoc networks (VANETs) have become one of the most relevant communication technologies that aim to reduce traffic congestion, traffic accidents, energy waste and pollution by...

Skip Graph, a member of the distributed hash table (DHT) family, has several benefits as an underlying structure in peer-to-peer (P2P) storage systems. In such systems, replication plays a key role on the system's performance. The traditional decentralized replication algorithms do not consider the locations of Skip Graph nodes in the network. Negl...

Skip Graph, a member of the distributed hash table (DHT) family, has several benefits as an underlying structure in peer-to-peer (P2P) storage systems. In such systems, replication plays a key role on the system's performance. The traditional decentralized replication algorithms do not consider the locations of Skip Graph nodes in the network. Negl...

Several Peer-to-Peer (P2P) protocols and applications have been developed to allow file distribution/sharing, video and music streaming, and data and information dissemination. These P2P systems are regularly used by a large number of users, both in desktop and mobile environments, and they generate a remarkable portion of the overall Internet traf...