arXiv subjects

Gunes Karabulut Kurt

Publications and source records attributed to Gunes Karabulut Kurt.

At least 109 records · Page 6Linked to original sources

arXiv2021

Localization Threats in Next-Generation Wireless Networks

The impact of localization systems in our daily lives is increasing. As next-generation networks will introduce hyperconnectivity with the emerging applications, this impact will undoubtedly further increase, proliferating the importance of the location information's reliability. As society becomes more dependent on this information in terms of the products and services, security solutions will have to be enriched to provide countermeasures sufficiently advanced to ever-evolving threats, forcing the joint design of communication and localization systems. This paper envisions integrated communication and localization systems by focusing on localization security. Also, conventional and next-generation attacks on localization are discussed along with an efficient attack detection method and test-bed-based demonstration, highlighting the need for effective countermeasures.

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arXiv2021

Communication, Computing, Caching, and Sensing for Next Generation Aerial Delivery Networks

This paper describes the envisioned interactions between the information and communication technology and aerospace industries to serve autonomous devices for next generation aerial parcel delivery networks. The autonomous features of fleet elements of the delivery network are enabled by the increased throughput, improved coverage, and near-user computation capabilities of vertical heterogeneous networks (VHetNets). A high altitude platform station (HAPS), located around 20~km above the ground level in a quasi-stationary manner, serves as the main enabler of the vision we present. In addition to the sensing potential of the HAPS nodes, the use of communication, computing, and caching capabilities demonstrate the attainability of the ambitious goal of serving a fully autonomous aerial fleet capable of addressing instantaneous user demands and enabling supply chain management interactions with delivery services in low-latency settings.

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arXiv2021

Securing the Inter-Spacecraft Links: Physical Layer Key Generation from Doppler Frequency Shift

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 Doppler frequency shift based measurements. In this way, the mobilities of the communication devices are exploited to generate secret keys, where this resource can be utilized in the environments that the channel fading based key generation methods are not available. The mobility of a spacecraft is modeled as the superposition of a pre-determined component and a dynamic component. We derive the maximum achievable secret key generation rate from the Doppler frequency shift. The proposed secret key generation procedure extracts the Doppler frequency shift in the form of nominal power spectral density samples (NPSDS). We propose a maximum-likelihood (ML) estimation for the NPSDS at the spacecrafts, then a uniform quantizer is utilized to obtain secret key bits. The key disagreement rate (KDR) is analytically obtained for the proposed key generation procedure. Through numerical studies, the tightness of the provided approximations is shown. Both the theoretical and numerical results demonstrate the validity and the practicality of the presented physical layer key generation procedure considering the security of the communication links of spacecrafts.

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arXiv2021

A Vision of Self-Evolving Network Management for Future Intelligent Vertical HetNet

Future integrated terrestrial-aerial-satellite networks will have to exhibit some unprecedented characteristics for the provision of both communications and computation services, and security for a tremendous number of devices with very broad and demanding requirements across multiple networks, operators, and ecosystems. Although 3GPP introduced the concept of self-organization networks (SONs) in 4G and 5G documents to automate network management, even this progressive concept will face several challenges as it may not be sufficiently agile in coping with the immense levels of complexity, heterogeneity, and mobility in the envisioned beyond-5G integrated networks. In the presented vision, we discuss how future integrated networks can be intelligently and autonomously managed to efficiently utilize resources, reduce operational costs, and achieve the targeted Quality of Experience (QoE). We introduce the novel concept of "self-evolving networks (SENs)" framework, which utilizes artificial intelligence, enabled by machine learning (ML) algorithms, to make future integrated networks fully automated and intelligently evolve with respect to the provision, adaptation, optimization, and management aspects of networking, communications, computation, and infrastructure nodes' mobility. To envisage the concept of SEN in future integrated networks, we use the Intelligent Vertical Heterogeneous Network (I-VHetNet) architecture as our reference. The paper discusses five prominent scenarios where SEN plays the main role in providing automated network management. Numerical results provide an insight on how the SEN framework improves the performance of future integrated networks. The paper presents the leading enablers and examines the challenges associated with the application of SEN concept in future integrated networks.

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arXiv2021

Performance Analyses of MRT/MRC in Dual-Hop NOMA Full-Duplex AF Relay Networks with Residual Hardware Impairments

This paper analyzes the performance of maximum-ratio transmission (MRT)/maximum-ratio combining (MRC) scheme in a dual-hop non-orthogonal multiple access (NOMA) full-duplex (FD) relay networks in the presence of residual hardware impairments (RHIs). The effects of channel estimation errors (CEEs) and imperfect successive interference cancellation are also considered for a realistic performance analysis. In the network, the base station and multiple users utilize MRT and MRC, respectively, while a dedicated relay consisting of two antennas, one for receiving and the other for broadcasting, operates in amplify-and-forward mode. For performance criterion, exact outage probability (OP) expression is derived for Nakagami-m fading channels. Furthermore, a tight lower bound and asymptotic expressions are also derived to provide more insights into the obtained OP in terms of diversity order and array gain. The obtained numerical results demonstrate the importance of loop-interference cancellation process at FD relay in order for the investigated system to perform better than half-duplex-NOMA counterpart. Also, a performance trade-off between the MRT and MRC schemes is observed in the presence of CEEs among users. Furthermore, it is shown that RHIs have a significant effect on the performance of users with lower power coefficients, however it does not change the diversity order. RHIs and CEEs have the most and least deterioration effects on the system performance, respectively.

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arXiv2020

High Altitude Platform Station based Super Macro Base Station (HAPS-SMBS) Constellations

High altitude platform station (HAPS) systems have recently attracted renewed attention. While terrestrial and satellite technologies are well-established for providing connectivity services, they face certain shortcomings and challenges, which could be addressed by complementing them with HAPS systems. In this paper, we envision a HAPS as a super macro base station, which we refer to as HAPS-SMBS, to provide connectivity in a plethora of applications. Unlike a conventional HAPS, which targets broad coverage for remote areas or disaster recovery, we envision next-generation HAPS-SMBS to have the necessary capabilities to address the high capacity, low latency, and computing requirements especially for highly populated metropolitan areas. This article focuses mainly on the potential opportunities, target use cases, and challenges that we expect to be associated with the design and implementation of the HAPS-SMBS based future wireless access architecture.

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arXiv2020

A Prospective Look: Key Enabling Technologies, Applications and Open Research Topics in 6G Networks

The fifth generation (5G) mobile networks are envisaged to enable a plethora of breakthrough advancements in wireless technologies, providing support of a diverse set of services over a single platform. While the deployment of 5G systems is scaling up globally, it is time to look ahead for beyond 5G systems. This is driven by the emerging societal trends, calling for fully automated systems and intelligent services supported by extended reality and haptics communications. To accommodate the stringent requirements of their prospective applications, which are data-driven and defined by extremely low-latency, ultra-reliable, fast and seamless wireless connectivity, research initiatives are currently focusing on a progressive roadmap towards the sixth generation (6G) networks. In this article, we shed light on some of the major enabling technologies for 6G, which are expected to revolutionize the fundamental architectures of cellular networks and provide multiple homogeneous artificial intelligence-empowered services, including distributed communications, control, computing, sensing, and energy, from its core to its end nodes. Particularly, this paper aims to answer several 6G framework related questions: What are the driving forces for the development of 6G? How will the enabling technologies of 6G differ from those in 5G? What kind of applications and interactions will they support which would not be supported by 5G? We address these questions by presenting a profound study of the 6G vision and outlining five of its disruptive technologies, i.e., terahertz communications, programmable metasurfaces, drone-based communications, backscatter communications and tactile internet, as well as their potential applications. Then, by leveraging the state-of-the-art literature surveyed for each technology, we discuss their requirements, key challenges, and open research problems.

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arXiv2020

Securing the Inter-Spacecraft Links: Doppler Frequency Shift based Physical Layer Key Generation

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 links as a unique secrecy source, spacecrafts aim to obtain identical secret keys from their individual observations. We obtain theoretical expressions for the key disagreement rate (KDR). Using generalized Gauss-Laguerre quadrature, we derive closed form expressions for the KDR. Through numerical studies, the tightness of the provided approximations are shown. Both the theoretical and numerical results demonstrate the validity and the practicality of the presented physical layer key generation procedure considering the security of the communication links of spacecrafts.

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arXiv2020

An Application-Driven Non-Orthogonal Multiple Access Enabled Computation Offloading Scheme

To cope with the unprecedented surge in demand for data computing for the applications, the promising concept of multi-access edge computing (MEC) has been proposed to enable the network edges to provide closer data processing for mobile devices (MDs). Since enormous workloads need to be migrated, and MDs always remain resource-constrained, data offloading from devices to the MEC server will inevitably require more efficient transmission designs. The integration of nonorthogonal multiple access (NOMA) technique with MEC has been shown to provide applications with lower latency and higher energy efficiency. However, existing designs of this type have mainly focused on the transmission technique, which is still insufficient. To further advance offloading performance, in this work, we propose an application-driven NOMA enabled computation offloading scheme by exploring the characteristics of applications, where the common data of the application is offloaded through multi-device cooperation. Under the premise of successfully offloading the common data, we formulate the problem as the maximization of individual offloading throughput, where the time allocation and power control are jointly optimized. By using the successive convex approximation (SCA) method, the formulated problem can be iteratively solved. Simulation results demonstrate the convergence of our method and the effectiveness of the proposed scheme.

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arXiv2020

Reconfigurable Intelligent Surfaces for the Connectivity of Autonomous Vehicles

The use of real-time software-controlled reconfigurable intelligent surface (RIS) units is proposed to increase the reliability of vehicle-to-everything (V2X) communications. The optimum placement problem of the RIS units is formulated by considering their sizes and operating modes. The solution of the problem is given, where it is shown that the placement of the RIS depends on the locations of the transmitter and the receiver. The proposed RIS-supported highway deployment can combat the high path loss experienced by the use of higher frequency bands, including the millimeter-wave and the terahertz bands, that are expected to be used in the next-generation wireless networks, enabling the use of the existing base station deployment plans to remain operational, while providing reliable and energy-efficient connectivity for autonomous vehicles.

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arXiv2020

A Polynomial Interpolation based Quantum Key Reconciliation Protocol: Error Correction without Information Leakage

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 correct all erroneous bits at the receiver without revealing information to the eavesdropper. We provide the exact frame error rate (FER) expression of the proposed protocol. The inherent nature of the proposed algorithm ensures correcting all erroneous bits if the algorithm succeeds. We present an information-theoretical proof that the revealed information during the key reconciliation process is equal to zero. We also provide a numerical comparison of our algorithm with the asymptotic performance of the error-correcting codes and two exemplary low-density-parity-check (LDPC) codes. The results highlight that our algorithm provides superior performance when compared to the LDPC codes, regardless of the distance between Alice and Bob. Furthermore, the proposed key reconciliation protocol is usable for the longer quantum link distances than the state-of-the-art protocols.

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arXiv2019

Authenticated Hand-Over Algorithm for Group Communication

Shamir or Blakley secret sharing schemes are used for the authentication process in the studies before, but still secure group authentication and hand-over process remain as challenges in group authentication approaches. In this study, a novel method is proposed to provide a secure group authentication. The proposed approach also enables a hand-over process between groups by using Lagrange's polynomial interpolation and Weil pairing in elliptic curve groups for wireless networks with mobility support. One of the advantages of our proposed scheme is that the computational load for a member in the group is lower than the other schemes in the state-of-the-art. It is also possible to authorize many users at the same time, not one-to-one as in the group authentication methods in current cellular networks including Long Term Evolution (LTE). Another advantage that is not covered in other secret sharing methods is that the proposed approach constitutes a practical solution for the hand-over of members between different groups. We have also proposed a solution for replay and man-in-the-middle attacks in secret exchange.

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arXiv2019

Authentication and Hand-Over Algorithms for IoT Group

Current advancements in mobility of devices and also Internet of Things (IoT) have replaced the central networks by distributed infrastructure. The more a network is distributed, the more the security of infrastructure and the communication is getting complex. The members in a distributed network create different groups according to their coverage area or their requirements. Mobility nature of the members brings a problem called hand-over of members between groups. Current authentication methods are not applicable due to the lack of resources in the devices.A lightweight authentication method and an easy and fast hand-over process are the current need for the distributed networks. Shamir Secret Sharing algorithm is used for the authentication process in the studies before, but still secure group authentication algorithm and hand-over process are challenges in the group authentication. In this study, a new method is proposed to provide a secure group authentication and hand-over process between groups based on Lagrange's Interpolation.

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arXiv2019

Wireless Network Reliability Analysis for Arbitrary Network Topologies

The outage performance of wireless networks with unstructured network topologies is investigated. The network reliability perspective of graph theory is used to obtain the network outage polynomial of generalized wireless networks by enumerating paths and cut-sets of its graph representation for both uncorrelated and correlated wireless channels. A relation is established between the max-flow min-cut theorem and key communication performance indicators. The diversity order is equal to the size of the minimum cut-set between source and destination, and the coding gain is the number of cut-sets with size equal to the minimum cut. An ergodic capacity analysis of networks with arbitrary topologies based on the network outage polynomial is also presented. Numerical results are used to illustrate the technical definitions and verify the derivations.

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arXiv2019

Transmit Antenna Selection for Massive MIMO-GSM with Machine Learning

A dynamic and flexible generalized spatial modulation (GSM) framework is proposed for massive MIMO systems. Our framework is leveraged on the utilization of machine learning methods for GSM in order to improve the error performance in presence of correlated channels and channel estimation errors. Both decision tree and multi-layer perceptrons approaches are adopted for the GSM transmitter. Simulation results indicate that in presence of real-life impairments machine learning based approaches provide a superior performance when compared to the classical Euclidean distance based approach. The observations are validated through measurement results over the designed $16\times 4$ MIMO test-bed using software defined radio nodes.

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arXiv2019

A Tutorial on Nonorthogonal Multiple Access for 5G and Beyond

Today's wireless networks allocate radio resources to users based on the orthogonal multiple access (OMA) principle. However, as the number of users increases, OMA based approaches may not meet the stringent emerging requirements including very high spectral efficiency, very low latency, and massive device connectivity. Nonorthogonal multiple access (NOMA) principle emerges as a solution to improve the spectral efficiency while allowing some degree of multiple access interference at receivers. In this tutorial style paper, we target providing a unified model for NOMA, including uplink and downlink transmissions, along with the extensions tomultiple inputmultiple output and cooperative communication scenarios. Through numerical examples, we compare the performances of OMA and NOMA networks. Implementation aspects and open issues are also detailed.

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arXiv2019

Joint Channel Coding and Cooperative Network Coding on PSK Constellations in Wireless Networks

In this paper, we consider the application of Reed- Solomon (RS) channel coding for joint error correction and cooperative network coding on non-binary phase shift keying (PSK) modulated signals. The relay first decodes the RS channel coded messages received each in a time slot from all sources before applying network coding (NC) by the use of bit-level exclusive OR (XOR) operation. The network coded resulting message is then channel encoded before its transmission to the next relay or to the destination according to the network configuration. This scenario shows superior performance in comparison with the case where the relay does not perform channel coding/decoding. For different orders of PSK modulation and different wireless configurations, simulation results demonstrate the improvements resulting from the use of RS channel codes in terms of symbol error rate (SER) versus signal-to-noise ratio (SNR).

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arXiv2019

Identification of Smart Jammers: Learning based Approaches Using Wavelet Representation

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 identification techniques, hidden in the time-frequency plane. These traces cannot be effectively identified through the use of the classical Fourier transform based time-frequency transformation (TFT) techniques with a fixed resolution. Inspired by the adaptive resolution property provided by the wavelet transforms, in this paper, we propose a jammer identification methodology that includes a pre-processing step to obtain a multi-resolution image, followed by the use of a classifier. Support vector machine (SVM) and deep convolutional neural network (DCNN) architectures are investigated as classifiers to automatically extract the features of the transformed signals and to classify them. Three different jamming attacks are considered, the barrage jamming that targets the complete transmission bandwidth, the synchronization signal jamming attack that targets synchronization signals and the reference signal jamming attack that targets the reference signals in an LTE downlink transmission scenario. The performance of the proposed approach is compared with the classical Fourier transform based TFT techniques, demonstrating the efficacy of the proposed approach in the presence of smart jammers.

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