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  • 1.
    Abd-Elmagid, Mohamed A.
    et al.
    Virginia Tech, VA 24061 USA.
    Dhillon, Harpreet S.
    Virginia Tech, VA 24061 USA.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    A Reinforcement Learning Framework for Optimizing Age of Information in RF-Powered Communication Systems2020In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 68, no 8, p. 4747-4760Article in journal (Refereed)
    Abstract [en]

    In this paper, we study a real-time monitoring system in which multiple source nodes are responsible for sending update packets to a common destination node in order to maintain the freshness of information at the destination. Since it may not always be feasible to replace or recharge batteries in all source nodes, we consider that the nodes are powered through wireless energy transfer (WET) by the destination. For this system setup, we investigate the optimal online sampling policy (referred to as the age-optimal policy) that jointly optimizes WET and scheduling of update packet transmissions with the objective of minimizing the long-term average weighted sum of Age of Information (AoI) values for different physical processes (observed by the source nodes) at the destination node, referred to as the sum-AoI. To solve this optimization problem, we first model this setup as an average cost Markov decision process (MDP) with finite state and action spaces. Due to the extreme curse of dimensionality in the state space of the formulated MDP, classical reinforcement learning algorithms are no longer applicable to our problem even for reasonable-scale settings. Motivated by this, we propose a deep reinforcement learning (DRL) algorithm that can learn the age-optimal policy in a computationally-efficient manner. We further characterize the structural properties of the age-optimal policy analytically, and demonstrate that it has a threshold-based structure with respect to the AoI values for different processes. We extend our analysis to characterize the structural properties of the policy that maximizes average throughput for our system setup, referred to as the throughput-optimal policy. Afterwards, we analytically demonstrate that the structures of the age-optimal and throughput-optimal policies are different. We also numerically demonstrate these structures as well as the impact of system design parameters on the optimal achievable average weighted sum-AoI.

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  • 2.
    Abd-Elmagid, Mohamed A.
    et al.
    Virginia Tech, VA 24061 USA.
    Dhillon, Harpreet S.
    Virginia Tech, VA 24061 USA.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    AoI-Optimal Joint Sampling and Updating for Wireless Powered Communication Systems2020In: IEEE Transactions on Vehicular Technology, ISSN 0018-9545, E-ISSN 1939-9359, Vol. 69, no 11, p. 14110-14115Article in journal (Refereed)
    Abstract [en]

    This paper characterizes the structure of the Age of Information (AoI)-optimal policy in wireless powered communication systems while accounting for the time and energy costs of generating status updates at the source nodes. In particular, for a single source-destination pair in which a radio frequency (RF)-powered source sends status updates about some physical process to a destination node, we minimize the long-term average AoI at the destination node. The problem is modeled as an average cost Markov Decision Process (MDP) in which, the generation times of status updates at the source, the transmissions of status updates from the source to the destination, and the wireless energy transfer (WET) are jointly optimized. After proving the monotonicity property of the value function associated with the MDP, we analytically demonstrate that the AoI-optimal policy has a threshold-based structure w.r.t. the state variables. Our numerical results verify the analytical findings and reveal the impact of state variables on the structure of the AoI-optimal policy. Our results also demonstrate the impact of system design parameters on the optimal achievable average AoI as well as the superiority of our proposed joint sampling and updating policy w.r.t. the generate-at-will policy.

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  • 3.
    Abd-Elmagid, Mohamed A.
    et al.
    Virginia Tech, VA 24061 USA.
    Dhillon, Harpreet S.
    Virginia Tech, VA 24061 USA.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Online Age-minimal Sampling Policy for RF-powered IoT Networks2019In: 2019 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM), IEEE , 2019Conference paper (Refereed)
    Abstract [en]

    In this paper, we study a real-time Internet of Things (IoT)-enabled monitoring system in which a source node (e.g., IoT device or an aggregator located near a group of IoT devices) is responsible for maintaining the freshness of information status at a destination node by sending update packets. Since it may not always be feasible to replace or recharge batteries in all IoT devices, we consider that the source node is powered by wireless energy transfer (WET) by the destination. For this system setup, we investigate the optimal online sampling policy that minimizes the long-term average Age-of-Information (AoI), referred to as the age-optimal policy. The age-optimal policy determines whether each slot should be allocated for WET or update packet transmission while considering the dynamics of battery level, AoI, and channel state information (CSI). To solve this optimization problem, we model this setup as an average cost Markov Decision Process (MDP). After analytically establishing the monotonicity property of the value function associated with the MDP, the age-optimal policy is proven to be a threshold based policy with respect to each of the system state variables. We extend our analysis to characterize the structural properties of the policy that maximizes average throughput for our system setup, referred to as the throughput-optimal policy. Afterwards, we analytically demonstrate that the structures of the age optimal and throughput-optimal policies are different. We also numerically demonstrate these structures as well as the impact of system design parameters on the optimal achievable average AoI.

  • 4.
    Abd-Elmagid, Mohamed A.
    et al.
    Virginia Tech, VA 24061 USA.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Dhillon, Arpreet S.
    Virginia Tech, VA 24061 USA.
    On the Role of Age of Information in the Internet of Things2019In: IEEE Communications Magazine, ISSN 0163-6804, E-ISSN 1558-1896, Vol. 57, no 12, p. 72-77Article in journal (Refereed)
    Abstract [en]

    In this article, we provide an accessible introduction to the emerging idea of Age of Information (AoI) that quantifies freshness of information and explore its possible role in the efficient design of freshness-aware Internet of Things (IoT). We start by summarizing the concept of AoI and its variants with emphasis on the differences between AoI and other well-known performance metrics in the literature, such as throughput and delay. Building on this, we explore freshness-aware IoT design for a network in which IoT devices sense potentially different physical processes and are supposed to frequently update the status of these processes at a destination node (e.g., a cellular base station). Inspired by recent interest, we also assume that these IoT devices are powered by wireless energy transfer by the destination node. For this setting, we investigate the optimal sampling policy that jointly optimizes wireless energy transfer and scheduling of update packet transmissions from IoT devices with the goal of minimizing long-term weighted sum-AoI. Using this, we characterize the achievable AoI region. We also compare this AoI-optimal policy with the one that maximizes average throughput (throughput-optimal policy), and demonstrate the impact of system state on their structures. Several promising directions for future research are also presented.

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  • 5.
    Agheli, Pouya
    et al.
    EURECOM, France.
    Pappas, Nikolaos
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Kountouris, Marios
    EURECOM, France.
    Semantic Source Coding for Two Users with Heterogeneous Goals2022In: 2022 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM 2022), IEEE , 2022, p. 4983-4988Conference paper (Refereed)
    Abstract [en]

    We study a multiuser system in which an information source provides status updates to two monitors with heterogeneous goals. Semantic filtering is first performed to select the most useful realizations for each monitor. Packets are then encoded and sent so that each monitor can timely fulfill its goal. In this regard, some realizations are important for both monitors, while every other realization is informative for only one monitor. We determine the optimal real codeword lengths assigned to the selected packet arrivals in the sense of maximizing a weighted sum of semantics-aware utility functions for the two monitors. Our analytical and numerical results provide the optimal design parameters for different arrival rates and highlight the improvement in timely status update delivery using semantic filtering and source coding.

  • 6.
    Agheli, Pouya
    et al.
    EURECOM, France.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology. Linköping University, Faculty of Science & Engineering.
    Kountouris, Marios
    EURECOM, France.
    Semantics-Aware Source Coding in Status Update Systems2022In: 2022 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS WORKSHOPS (ICC WORKSHOPS), IEEE , 2022, p. 169-174Conference paper (Refereed)
    Abstract [en]

    We consider a communication system in which the destination receives status updates from an information source that observes a physical process. The transmitter performs semantics-empowered filtering as a means to send only the most "important" samples to the receiver in a timely manner. As a first step, we explore a simple policy where the transmitter selects to encode only a fraction of the least frequent realizations of the observed random phenomenon, treating the remaining ones as not not informative. For this timely source coding problem, we derive the optimal codeword lengths in the sense of maximizing a semantics-aware utility function and minimizing a quadratic average length cost. Our numerical results show the optimal number of updates to transmit for different arrival rates and encoding costs and corroborate that semantic filtering results in higher performance in terms of timely delivery of important updates.

  • 7.
    Aijaz, Adnan
    et al.
    Toshiba Europe Ltd, England.
    Dawy, Zaher
    Amer Univ Beirut, Lebanon.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Simsek, Meryem
    Int Comp Sci Inst Berkeley, CA USA.
    Oteafy, Sharief
    Depaul Univ, IL 60604 USA.
    Holland, Oliver
    Adv Wireless Technol Grp Ltd, England.
    The IEEE P1918.1 Reference Architecture Framework for the Tactile Internet and a Case Study2020In: 2020 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM), IEEE , 2020Conference paper (Refereed)
    Abstract [en]

    The term Tactile Internet broadly refers to a communication network that is capable of delivering control, touch, and sensing/actuation information in real-time. The Tactile Internet is currently a topic of interest for various standardization bodies. The emerging IEEE P1918.1 standards working group is focusing on defining a framework for the Tactile Internet. The main objective of this work is to present the IEEE P1918.1 reference architecture framework for the Tactile Internet. The paper provides an in-depth survey of various architectural aspects including the key entities, the interfaces, the functional capabilities, and the protocol stack. A case study has been presented as a manifestation of the architecture. Performance evaluation demonstrates the impact of functional capabilities and the underlying enablers on user-level utility pertaining to a generic Tactile Internet application.

  • 8.
    Allipuram, Sujatha
    et al.
    Indian Inst Technol Kharagpur, India.
    Mohapatra, Parthajit
    Indian Inst Technol Tirupati, India.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Parmar, Shabnam
    Intel Technol India Pvt Ltd, India.
    Chakrabarti, Saswat
    Indian Inst Technol Kharagpur, India.
    Performance Analysis of a MIMO System With Bursty Traffic in the Presence of Energy Harvesting Jammer2022In: IEEE TRANSACTIONS ON GREEN COMMUNICATIONS AND NETWORKING, ISSN 2473-2400, Vol. 6, no 2, p. 1157-1172Article in journal (Refereed)
    Abstract [en]

    This paper explores the role of multiple antennas in mitigating jamming attacks for the Rayleigh fading environment with exogenous random traffic arrival. The jammer is assumed to have energy harvesting ability where energy arrives according to Bernoulli process. The outage probabilities are derived with different assumptions on the number of antennas at the transmitter and receiver. The outage probability for the Alamouti space-time code is also derived. The work characterizes the average service rate for different antenna configurations taking into account of random arrival of data and energy at the transmitter and jammer, respectively. In many practical applications, latency and timely updates are of importance, thus, delay and Average Age of Information (AAoI) are the meaningful metrics to be considered. The work characterizes these metrics under jamming attack. The impact of finite and infinite energy battery size at the jammer on various performance metrics is also explored. Two optimization problems are considered to explore the interplay between AAoI and delay under jamming attack. Furthermore, our results show that Alamouti code can significantly improve the performance of the system even under jamming attack, with less power budget. The paper also demonstrates how the developed results can be useful for multiuser scenarios.

  • 9.
    Angelakis, Vangelis
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Avgouleas, Ioannis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Fitzgerald, Emma
    Lund University, Sweden.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. University of Maryland, MD 20742 USA.
    Allocation of Heterogeneous Resources of an IoT Device to Flexible Services2016In: IEEE Internet of Things Journal, ISSN 2327-4662, Vol. 3, no 5, p. 691-700Article in journal (Refereed)
    Abstract [en]

    Internet-of-Things (IoT) devices can be equipped with multiple heterogeneous network interfaces. An overwhelmingly large amount of services may demand some or all of these interfaces available resources. Herein, we present a precise mathematical formulation of assigning services to interfaces with heterogeneous resources in one or more rounds. For reasonable instance sizes, the presented formulation produces optimal solutions for this computationally hard problem. We prove the NP-completeness of the problem and develop two algorithms to approximate the optimal solution for big instance sizes. The first algorithm allocates the most demanding service requirements first, considering the average cost of interfaces resources. The second one calculates the demanding resource shares and allocates the most demanding of them first by choosing randomly among equally demanding shares. Finally, we provide simulation results giving insight into services splitting over different interfaces for both cases.

  • 10.
    Angelakis, Vangelis
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Avgouleas, Ioannis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Flexible allocation of heterogeneous resources to services on an IoT device2015In: 2015 IEEE Conference on Computer Communications Workshops (INFOCOM WKSHPS), Institute of Electrical and Electronics Engineers (IEEE), 2015, p. 99-100Conference paper (Refereed)
    Abstract [en]

    In the Internet of Things (IoT), devices and gateways may be equipped with multiple, heterogeneous network interfaces which should be utilized by a large number of services. In this work, we model the problem of assigning services' resource demands to a device's heterogeneous interfaces and give a Mixed Integer Linear Program (MILP) formulation for it. For meaningful instance sizes the MILP model gives optimal solutions to the presented computationally-hard problem. We provide insightful results discussing the properties of the results on the properties of the derived solutions with respect to the splitting of services to different interfaces.

  • 11.
    Arvanitaki, Antonia
    et al.
    Linköping University, Department of Computer and Information Science, Human-Centered systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Modeling of a UAV-based Data Collection System2017In: 2017 IEEE 22ND INTERNATIONAL WORKSHOP ON COMPUTER AIDED MODELING AND DESIGN OF COMMUNICATION LINKS AND NETWORKS (CAMAD), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    Unmanned Aerial Vehicles (UAVs) have been extensively studied the past years for various applications. In this work, we propose a Markov chain to model the movement of a single FAY deployed for data collection from remote sensors. Furthermore, we introduce a second Markov chain to model the irregularities of the UAVs movement when it is in transit. We investigate the impact of the distance of the FAV from the sensor on the success probability of information transmission. We provide numerical evaluation of the theoretical results.

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  • 12.
    Arvanitaki, Antonia
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Mohapatra, Parthajit
    Indian Institute of Technology, Tirupati, India.
    Secrecy in Congestion-Aware Broadcast Channels2021In: Proc. Wireless Days Conference (WD) 2021, Institute of Electrical and Electronics Engineers (IEEE), 2021Conference paper (Refereed)
    Abstract [en]

    Congestion-aware scheduling in the case of traditional downlink cellular communication has neglected the heterogeneity in terms of secrecy among different clients. In this paper, we study a two-user congestion-aware broadcast channel with heterogeneous traffic and different security requirements. The traffic with security requirements is intended for a legitimate user and it has bursty nature. The incoming packets are stored in a queue at the source. Furthermore, there is a second traffic flow intended for another user, it is delay tolerant and does not have secrecy constraints. The receiver which needs to be served with confidential data has full-duplex capabilities, and it can send a jamming signal to hinder eavesdropping of its data at the other user. We consider two randomized policies for selecting which packets to transmit, one is congestion-aware by taking into consideration the queue size, whereas the other one is non-congestion-aware. We analyse the throughput and the delay performance under two decoding schemes at the receivers and provide insights into their relative security performance and into how congestion control at the queue holding confidential information can help decrease the average delay per packet. We show that the two policies have the same secrecy performance for large random access probabilities. The derived results also take account of the self-interference caused at the receiver for whom confidential data is intended due to its full-duplex operation while jamming the communication at the other user.

  • 13.
    Arvanitaki, Antonia
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Mohapatra, Parthajit
    Indian Inst Technol, India.
    Burdakov, Oleg
    Linköping University, Department of Mathematics, Applied Mathematics. Linköping University, Faculty of Science & Engineering.
    Performance analysis of congestion-aware secure broadcast channels2021In: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2021, no 1, article id 178Article in journal (Refereed)
    Abstract [en]

    Congestion-aware scheduling in case of downlink cellular communication has ignored the distribution of diverse content to different clients with heterogeneous secrecy requirements. Other possible application areas that encounter the preceding issue are secure offloading in mobile-edge computing, and vehicular communication. In this paper, we extend the work in Arvanitaki et al. (SN Comput Sci 1(1):53, 2019) by taking into consideration congestion and random access. Specifically, we study a two-user congestion-aware broadcast channel with heterogeneous traffic and different security requirements. We consider two randomized policies for selecting which packets to transmit, one is congestion-aware by taking into consideration the queue size, whereas the other one is congestion-agnostic. We analyse the throughput and the delay performance under two decoding schemes at the receivers, and provide insights into their relative security performance and into how congestion control at the queue holding confidential information can help decrease the average delay per packet. We show that the congestion-aware policy provides better delay, throughput, and secrecy performance for large arrival packet probabilities at the queue holding the confidential information. The derived results also take account of the self-interference caused at the receiver for whom confidential data is intended due to its full-duplex operation while jamming the communication at the other user. Finally, for two decoding schemes, we formulate our problems in terms of multi-objective optimization, which allows for finding a trade-off between the average packet delay for packets intended for the legitimate user and the throughput for the other user under congestion-aware policy.

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  • 14.
    Arvanitaki, Antonia
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Mohapatra, Parthajit
    Indian Inst Technol Tirupati, India.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Delay Performance of a Two-User Broadcast Channel with Security Constraints2018In: 2018 GLOBAL INFORMATION INFRASTRUCTURE AND NETWORKING SYMPOSIUM (GIIS), IEEE , 2018Conference paper (Refereed)
    Abstract [en]

    In this paper we consider the two-user broadcast channel with security constraints. We assume that one of the receivers has a secrecy constraint; i.e., its packets need to be kept secret from the other receiver. The receiver with secrecy constraint has full-duplex capability to transmit a jamming signal to increase its secrecy. We derive the average delay per packet and provide simulation and numerical results, where we compare different performance metrics for the cases when the legitimate receiver performs successive decoding and when both receivers treat interference as noise.

  • 15.
    Arvanitaki, Antonia
    et al.
    Linköping University, Department of Computer and Information Science, Software and Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Mohapatra, Parthajit
    Indian Institute of Technology, Tirupati, India.
    Carlsson, Niklas
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Delay Performance of a Two-User Broadcast Channel with Security Constraints2020In: SN Computer Science, ISSN 2661-8907, Vol. 1, no 1, article id 53Article in journal (Refereed)
    Abstract [en]

    In this paper, we consider the two-user broadcast channel with security constraints. We assume that a source broadcasts packets to two receivers, and that one of them has secrecy constraints, i.e., its packets need to be kept secret from the other receiver. The receiver with secrecy constraint has full-duplex capability, allowing it to transmit a jamming signal to increase its secrecy. We derive the average delay per packet and provide simulations and numerical results, where we compare different performance metrics for the cases when both receivers treat interference as noise, when the legitimate receiver performs successive decoding, and when the eavesdropper performs successive decoding. The results show that successive decoding provides better average packet delay for the legitimate user. Furthermore, we define a new metric that characterizes the reduction on the success probability for the legitimate user that is caused by the secrecy constraint. The results show that secrecy poses a significant amount of packet delay for the legitimate receiver when either receiver performs successive decoding. We also formulate an optimization problem, wherein the throughput of the eavesdropper is maximized under delay and secrecy rate constraints at the legitimate receiver. We provide numerical results for the optimization problem, where we show the trade-off between the transmission power for the jamming and the throughput of the non-legitimate receiver. The results provide insights into how channel ordering and encoding differences can be exploited to improve performance under different interference conditions.

  • 16.
    Avgouleas, Ioannis
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Utilizing multiple full-duplex relays in wireless systems with multiple packet reception2014In: 2014 IEEE 19th International Workshop on Computer Aided Modeling and Design of Communication Links and Networks (CAMAD), IEEE, 2014, p. 193-197Conference paper (Refereed)
    Abstract [en]

    Relay nodes with physical layer cooperation have been used extensively to assist users' transmissions in wireless networks. This network level cooperation has been lately been gaining popularity and analytical expressions of the performance of a network with up to two relay nodes exist in recent literature. In this work, we give simulation results outlining the potential network level benefits of using multiple full-duplex relay nodes. We examine configurations where multiple full-duplex transceivers offer consistent improvement and provide guidelines on using them different network conditions.

  • 17.
    Avgouleas, Ioannis
    et al.
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    A wireless caching helper system with heterogeneous traffic and random availability2021In: EURASIP Journal on Wireless Communications and Networking, ISSN 1687-1472, E-ISSN 1687-1499, Vol. 2021, no 1, article id 69Article in journal (Refereed)
    Abstract [en]

    Multimedia content streaming from Internet-based sources emerges as one of the most demanded services by wireless users. In order to alleviate excessive traffic due to multimedia content transmission, many architectures (e.g., small cells, femtocells, etc.) have been proposed to offload such traffic to the nearest (or strongest) access point also called "helper". However, the deployment of more helpers is not necessarily beneficial due to their potential of increasing interference. In this work, we evaluate a wireless system which can serve both cacheable and non-cacheable traffic. More specifically, we consider a general system in which a wireless user with limited cache storage requests cacheable content from a data center that can be directly accessed through a base station. The user can be assisted by a pair of wireless helpers that exchange non-cacheable content as well. Files not available from the helpers are transmitted by the base station. We analyze the system throughput and the delay experienced by the cached user and show how these performance metrics are affected by the packet arrival rate at the source helper, the availability of caching helpers, the caches parameters, and the users request rate by means of numerical results.

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  • 18.
    Avgouleas, Ioannis
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Cacheable and Non-Cacheable Traffic Interplay in a Relay-Assisted Wireless Network2020In: ICC 2020 - 2020 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC), Institute of Electrical and Electronics Engineers (IEEE), 2020Conference paper (Refereed)
    Abstract [en]

    We study a discrete-time wireless network that serves both cacheable and non-cacheable traffic with assistance of a relay node with storage capabilities for both types of traffic. We investigate how allocating the storage capacity to cacheable and non-cacheable traffic affects the network throughput. Our numerical results provide useful insights by varying not only the allocation of cacheable to non-cacheable storage but also the rate by which non-cacheable content is transmitted, the rate by which cacheable content is requested, as well as different popularity distributions of the cached files.

  • 19.
    Avgouleas, Ioannis
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Cooperative Wireless Networking with Probabilistic On/Off Relaying2015In: 2015 IEEE 81ST VEHICULAR TECHNOLOGY CONFERENCE (VTC SPRING), IEEE , 2015Conference paper (Refereed)
    Abstract [en]

    In this work, we investigate the operation of energy efficient relay nodes assisting the transmission of packets from a number of users to a destination node. We study the impact of switching randomly a fraction of the relays on and off to the aggregate throughput, the average queue size and delay per packet of systems with relays transmitting in either Full-or Half-Duplex mode and under different channel transmissions characteristics. Furthermore, we prove analytically and illustrate via simulation means how these network metrics are affected.

  • 20.
    Avgouleas, Ioannis
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Performance Evaluation of Wireless Caching Helper Systems2019In: 2019 INTERNATIONAL CONFERENCE ON WIRELESS AND MOBILE COMPUTING, NETWORKING AND COMMUNICATIONS (WIMOB), IEEE , 2019Conference paper (Refereed)
    Abstract [en]

    In this work, we evaluate a wireless system in which we distinguish between cacheable and non-cacheable traffic. More specifically, we consider a general system in which a wireless user with limited cache storage requests cacheable content from a data center that can be directly accessed through a base station. The user can be assisted by a pair of wireless helpers that exchange non-cacheable content. Packets arrive at the queue of the source helper in bursts. Each helper has its own caches to assist the users requests for cacheable content. Files not available from the helpers are transmitted by the base station. We analyze the system throughput and the delay experienced by the user and show how they are affected by the packet arrival rate at the source helper, the availability of caching helpers, the caches parameters, and the users request rate by means of numerical results.

  • 21.
    Avgouleas, Ioannis
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Scheduling Services on an IoT Device Under Time-Weighted Pricing2017In: Conference Proceedings IEEE 28th Annual International Symposium on Personal, Indoor, and Mobile Radio Communications (PIMRC): Workshop on "Communications for Networked Smart Cities", IEEE conference proceedings, 2017, p. 1-5Conference paper (Refereed)
    Abstract [en]

    The emerging vision of smart cities necessitates the use of Internet of Things (IoT) network devices to implement sustainable solutions that will improve the operations of urban areas. A massive amount of smart cities services may demand allocation of computational resources, such as processing power or storage, that IoT devices offer. Within this context, we present an IoT network device comprising interfaces with one specific computational resource available. The efficient utilization of available IoT resources would improve the Quality of Service (QoS) of the IoT network that serves the smart city. All resource allocations must be completed within a given scheduling window and every service is parametrized by a pricing weight function to indicate its tolerance to be served at the beginning of the scheduling window. We propose a mathematical optimization formulation to minimize the total cost of allocating all demands within the scheduling window considering the tolerance level of each service at the same time. Moreover, we prove that the problem is computationally hard and we provide numerical results to gain insight into the impact of different pricing weight functions on the allocations’ distribution within the scheduling window.

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    Scheduling Services on an IoT Device Under Time-Weighted Pricing
  • 22.
    Avgouleas, Ioannis
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Probabilistic Cooperation of a Full-Duplex Relay in Random Access Networks2017In: IEEE Access, E-ISSN 2169-3536, Vol. 5, p. 7394-7404Article in journal (Refereed)
    Abstract [en]

    In this paper, we analyze the probabilistic cooperation of a full-duplex relay in a multiuser random-access network. The relay is equipped with on/off modes for the receiver and the transmitter independently. These modes are modeled as probabilities by which the receiver and the transmitter are activated. We provide analytical expressions for the performance of the relay queue, such as arrival and service rates, stability conditions, and the average queue size. We optimize the relays operation setup to maximize the network-wide throughput while, simultaneously, we keep the relays queue stable and lower the relays receptions and transmissions. Furthermore, we study the effect of the SINR threshold and the self-interference coefficient on the per-user and network-wide throughput. For low SINR threshold, we show under which circumstances it is beneficial to switch off the relay completely, or switch off the relays receiver only.

  • 23.
    Avgouleas, Ioannis
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Virtual Network Functions Scheduling under Delay-Weighted Pricing2019In: IEEE Networking Letters, E-ISSN 2576-3156, Vol. 1, no 4, p. 160-163Article in journal (Refereed)
    Abstract [en]

    We consider a cost minimization problem for High Volume Servers (HVS) equipped with Virtual Machines (VMs) to serve Virtual Network Functions (VNF) demands for resources. Given a scheduling period, a central scheduler decides which VM to use for each VNF demand. Each VM can be activated or disabled with different costs. Each VNF has a delay-weighted pricing function to indicate its completion time tolerance. We prove the NP-completeness of the problem and develop an algorithm based on Lagrangian relaxation and subgradient optimization to deal with this computational complexity. Finally, our numerical results demonstrate our algorithm’s effectiveness compared to two benchmarks.

  • 24.
    Boonphoka, Terut
    et al.
    Huazhong Univ Sci and Technol, Peoples R China.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Zhong, Yi
    Huazhong Univ Sci and Technol, Peoples R China.
    Ge, Xiaohu
    Huazhong Univ Sci and Technol, Peoples R China.
    Uthansakul, Peerapong
    Suranaree Univ Technol, Thailand.
    Quek, Tony Q. S.
    Singapore Univ Technol and Design, Singapore.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Performance Analysis of Full-Duplex Relay Channel with Random Access2017In: 2017 IEEE GLOBECOM WORKSHOPS (GC WKSHPS), IEEE , 2017Conference paper (Refereed)
    Abstract [en]

    Relay is useful in wireless networks to assist the sources to deliver packets to the destinations. In this paper, the effect of full-duplex relay with random access is evaluated. Based on the model of two sources, two destinations, and one full-duplex relay with two queues, we obtain the analytical expressions for significant parameters, such as the arrival rate and the service rate for queues at the relay. Then, we evaluate the per-user throughput and the per-user average delay as functions of the signal-to-interference-plus-noise ratio (SINR) threshold and the self-interference cancelation coefficient through both analysis and simulation. We also consider the case where the two queues at the relay have different priorities and evaluate the effect of different transmit probabilities on the system performance. Our results reveal that the transmit probabilities and the transmit powers have an enormous impact on the self-interference, the average size and the empty probability of the queues. Specially, the queues tend to be stable when increasing the transmit probabilities and the transmit powers.

  • 25.
    Chen, Bolin
    et al.
    Department of Electronic and Electrical Engineering, The University of Sheffield, Sheffield, UK.
    Chen, Zheng
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Zhang, Jie
    Department of Electronic and Electrical Engineering, The University of Sheffield, Sheffield, UK.
    Modeling and Analysis of MPTCP Proxy-based LTE-WLAN Path Aggregation2017In: 2017 IEEE Global Communications Conference (GLOBECOM), Proceedings Singapore 4 – 8 December 2017, IEEE Communications Society, 2017, p. 1-7Conference paper (Refereed)
    Abstract [en]

    Long Term Evolution (LTE)-Wireless Local Area Network (WLAN) Path Aggregation (LWPA) based on Multi- path Transmission Control Protocol (MPTCP) has been under standardization procedure as a promising and cost-efficient solution to boost Downlink (DL) data rate and handle the rapidly increasing data traffic. This paper aims at providing tractable analysis for the DL performance evaluation of large-scale LWPA networks with the help of tools from stochastic geometry. We consider a simple yet practical model to determine under which conditions a native WLAN Access Point (AP) will work under LWPA mode to help increasing the received data rate. Using stochastic spatial models for the distribution of WLAN APs and LTE Base Stations (BSs), we analyze the density of active LWPA- mode WiFi APs in the considered network model, which further leads to closed-form expressions on the DL data rate and area spectral efficiency (ASE) improvement. Our numerical results illustrate the impact of different network parameters on the performance of LWPA networks, which can be useful for further performance optimization. 

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    Modeling and Analysis of MPTCP Proxy-based LTE-WLAN Path Aggregation
  • 26.
    Chen, Bolin
    et al.
    Univ Sheffield, England.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Chen, Zheng
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Zhang, Jie
    Univ Sheffield, England.
    LTE-WLAN Aggregation with Bursty Data Traffic and Randomized Flow Splitting2019In: ICC 2019 - 2019 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC), IEEE , 2019Conference paper (Refereed)
    Abstract [en]

    We investigate the effect of bursty traffic in an LTE and Wi-Fi aggregation (LWA)-enabled network, where part of the LTE traffic is offloaded to Wi-Fi access points (APs) to boost the performance of LTE networks. A Wi-Fi AP maintains two queues containing data intended for the LWA-mode user and the native Wi-Fi user, and it is allowed to serve them simultaneously by using superposition coding (SC). With respect to the existing works on LWA, the novelty of our study consists of a random access protocol allowing the Wi-Fi AP to serve the native Wi-Fi user with probabilities that depend on the queue size of the LWA-mode data. We analyze the throughput of the native Wi-Fi network, accounting for different transmitting probabilities of the queues, the traffic flow splitting between LTE and Wi-Fi, and the operating mode of the LWA user with both LTE and Wi-Fi interfaces. Our results provide fundamental insights in the throughput behavior of such aggregated systems, which are essential for further investigation in larger topologies.

  • 27.
    Chen, Bolin
    et al.
    Univ Sheffield, England.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Chen, Zheng
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Zhang, Jie
    Univ Sheffield, England.
    Throughput and Delay Analysis of LWA With Bursty Traffic and Randomized Flow Splitting2019In: IEEE Access, E-ISSN 2169-3536, Vol. 7, p. 24667-24678Article in journal (Refereed)
    Abstract [en]

    We investigate the effect of bursty traffic in a long term evolution (LTE) and Wi-Fi aggregation (LWA)-enabled network. The LTE base station routes packets of the same IP flow through the LIE and Wi-Fi links independently. We motivate the use of superposition coding at the LWA-mode Wi-Fi access point (AP) so that it can serve LWA users and Wi-Fi users simultaneously. A random access protocol is applied in such system, which allows the native-mode AP to access the channel with probabilities that depend on the queue size of the LWA-mode AP to avoid impeding the performance of the LWA-enabled network. We analyze the throughput of the native Wi-Fi network and the delay experienced by the LWA users, accounting for the native-mode AP access probability, the traffic flow splitting between LTE and Wi-Fi, and the operating mode of the LWA user with both LIE and Wi-Fi interfaces. Our results show some fundamental tradeoffs in the throughput and delay behavior of LWA-enabled networks, which provide meaningful insight into the operation of such aggregated systems.

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    fulltext
  • 28.
    Chen, Bolin
    et al.
    Univ Sheffield, England.
    You, Lei
    Uppsala Univ, Sweden.
    Yuan, Di
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Zhang, Jie
    Univ Sheffield, England.
    Resource Optimization for Joint LWA and LTE-U in Load-Coupled and Multi-Cell Networks2019In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 23, no 2, p. 330-333Article in journal (Refereed)
    Abstract [en]

    We consider the performance optimization of multi-cell networks with LTE and Wi-Fi aggregation (LWA) and LTE-unlicensed (LTE-U) with sharing of the unlicensed band. Theoretical results are derived to enable an algorithm to approach the optimum. Numerical results show the algorithms effectiveness and benefits of joint use of LWA and LTE-U.

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    fulltext
  • 29.
    Chen, Zheng
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Björnson, Emil
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Larsson, Erik G
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Age of Information in a Multiple Access Channel with Heterogeneous Traffic and an Energy Harvesting Node2019In: IEEE CONFERENCE ON COMPUTER COMMUNICATIONS WORKSHOPS (IEEE INFOCOM 2019 WKSHPS), IEEE , 2019, p. 662-667Conference paper (Refereed)
    Abstract [en]

    Age of Information (AoI) is a newly appeared concept and metric to characterize the freshness of data. In this work, we study the delay and AoI in a multiple access channel (MAC) with two source nodes transmitting different types of data to a common destination. The first node is grid-connected and its data packets arrive in a bursty manner, and at each time slot it transmits one packet with some probability. Another energy harvesting (EH) sensor node generates a new status update with a certain probability whenever it is charged. We derive the delay of the grid-connected node and the AoI of the EH sensor as functions of different parameters in the system. The results show that the mutual interference has a non-trivial impact on the delay and age performance of the two nodes.

  • 30.
    Chen, Zheng
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Björnson, Emil
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Larsson, Erik G.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Optimizing Information Freshness in a Multiple Access Channel With Heterogeneous Devices2021In: IEEE Open Journal of the Communications Society, E-ISSN 2644-125X, Vol. 2, p. 456-470Article in journal (Refereed)
    Abstract [en]

    In this work, we study age-optimal scheduling with stability constraints in a multiple access channel with two heterogeneous source nodes transmitting to a common destination. The first node is connected to a power grid and it has randomly arriving data packets. Another energy harvesting (EH) sensor monitors a stochastic process and sends status updates to the destination. We formulate an optimization problem that aims at minimizing the average age of information (AoI) of the EH node subject to the queue stability condition of the grid-connected node. First, we consider a Probabilistic Random Access (PRA) policy where both nodes make independent transmission decisions based on some fixed probability distributions. We show that with this policy, the average AoI is equal to the average peak AoI, if the EH node only sends freshly generated samples. In addition, we derive the optimal solution in closed form, which reveals some interesting properties of the considered system. Furthermore, we consider a Drift-Plus-Penalty (DPP) policy and develop AoI-optimal and peak-AoI-optimal scheduling algorithms using the Lyapunov optimization theory. Simulation results show that the DPP policy outperforms the PRA policy in various scenarios, especially when the destination node has low multi-packet reception capabilities.

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    fulltext
  • 31.
    Chen, Zheng
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Kountouris, Marios
    Mathematical and Algorithmic Sciences Lab, France Research Center, Huawei Technologies France SASU, Boulogne-Billancourt, France.
    Energy Harvesting in Delay-Aware Cognitive Shared Access Networks2017In: IEEE Workshop on Emerging Energy Harvesting Solutions for 5G Networks (5G-NRG): May 2017, Paris, France., IEEE Press, 2017, p. 168-173Conference paper (Refereed)
    Abstract [en]

    In this work, we study the effect of energy harvesting in a cognitive shared access network with delay constraints on the primary user. We model the distribution of secondary nodes by a homogeneous Poisson point process (PPP), while the primary user is located at fixed location. The secondary users are assumed to have always packets to transmit whilst the primary transmitter has bursty traffic. We assume an energy harvesting zone around the primary transmitter and a guard zone around the primary receiver. The secondary users are transmitting in a random access manner, however, transmissions of secondary nodes are restricted by their battery status and location. Targeting at achieving the maximum secondary throughput under primary delay constraints, we analyze the impact of various parameters on the performance of the considered network. Our results provide insights into the optimization of access protocol parameters for the energy harvesting-based cognitive shared access network with delay constraints.

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    fulltext
  • 32.
    Chen, Zheng
    et al.
    University of Paris Sud, France.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Kountouris, Marios
    Huawei Technology Co Ltd, France.
    Probabilistic Caching in Wireless D2D Networks: Cache Hit Optimal Versus Throughput Optimal2017In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 21, no 3, p. 584-587Article in journal (Refereed)
    Abstract [en]

    Departing from the conventional cache hit optimization in cache-enabled wireless networks, we consider an alternative optimization approach for the probabilistic caching placement in stochastic wireless D2D caching networks taking into account the reliability of D2D transmissions. Using tools from stochastic geometry, we provide a closed-form approximation of cache-aided throughput, which measures the density of successfully served requests by local device caches, and we obtain the optimal caching probabilities via numerical optimization. Compared with the cache-hit-optimal case, the optimal caching probabilities obtained by cache-aided throughput optimization show notable gain in terms of the density of successfully served user requests, particularly in dense user environments.

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    fulltext
  • 33.
    Chen, Zheng
    et al.
    University of Paris Sud, France.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Kountouris, Marios
    Huawei Technology Co Ltd, Peoples R China.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Throughput Analysis of Smart Objects with Delay Constraints2016In: 2016 IEEE 17TH INTERNATIONAL SYMPOSIUM ON A WORLD OF WIRELESS, MOBILE AND MULTIMEDIA NETWORKS (WOWMOM), IEEE , 2016Conference paper (Refereed)
    Abstract [en]

    In this paper, we analyze a shared access network with one primary device and randomly distributed smart objects with secondary priority. Assuming random traffic at the primary device and saturated queues at the smart objects with secondary priority, an access protocol is employed to adjust the random access probabilities of the smart objects depending on the congestion level of the primary. We characterize the maximum throughput of the secondary network with respect to delay constraints on the primary. Our results highlight the impact of system design parameters on the delay and throughput behavior of the shared access network with massive number of connected objects.

  • 34.
    Chen, Zheng
    et al.
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Kountouris, Marios
    Huawei Technol Co Ltd, France.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Throughput With Delay Constraints in a Shared Access Network With Priorities2018In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, no 9, p. 5885-5899Article in journal (Refereed)
    Abstract [en]

    In this paper, we analyze a shared access network with a fixed primary node and randomly distributed secondary nodes whose spatial distribution follows a poisson point process. The secondary nodes use a random access protocol allowing them to access the channel with probabilities that depend on the queue size of the primary node. Assuming a system with multipacket reception receivers, having bursty packet arrivals at the primary and saturated traffic at the secondary nodes, our protocol can be tuned to alleviate congestion at the primary. We analyze the throughput of the secondary network and the primary average delay, as well as the impact of the secondary node access probability and transmit power. We formulate an optimization problem to maximize the throughput of the secondary network under delay constraints for the primary node; in the case of no congestion control, the optimal access probability can be provided in closed form. Our numerical results illustrate the effect of network operating parameters on the performance of the proposed priority-based shared access protocol.

  • 35.
    Chen, Zhengchuan
    et al.
    Chongqing Univ, Peoples R China.
    Deng, Dapeng
    Chongqing Univ, Peoples R China.
    Yang, Howard H.
    Zhejiang Univ, Peoples R China.
    Pappas, Nikolaos
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Hu, Limei
    Chongqing Univ, Peoples R China.
    Jia, Yunjian
    Chongqing Univ, Peoples R China.
    Wang, Min
    Chongqing Univ Posts & Telecommun, Peoples R China.
    Quek, Tony Q. S.
    Singapore Univ Technol & Design, Singapore; Kyung Hee Univ, South Korea.
    Analysis of Age of Information in Dual Updating Systems2023In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 22, no 11, p. 8003-8019Article in journal (Refereed)
    Abstract [en]

    We study the average Age of Information (AoI) and peak AoI (PAoI) of a dual-queue status update system that monitors a common stochastic process through two independent channels. Although the double queue parallel transmission is instrumental in reducing AoI, the out of order of data arrivals also imposes a significant challenge to the performance analysis. We consider two settings: the M-M system where the service time of two servers is exponentially distributed; the M-D system in which the service time of one server is exponentially distributed and that of the other is deterministic. For the two dual-queue systems, closed-form expressions of average AoI and PAoI are derived by resorting to the graphic method and state flow graph analysis method. Our analysis reveals that when the two servers have the same service rate, compared with the single-queue system with an exponentially distributed service time, the average PAoI and the average AoI of the M-M system decrease by 33.3% and 37.5%, respectively, and those of the M-D system decrease by 27.7% and 39.7%, respectively. Numerical results show that the two dual-queue systems also outperform the M/M/2 single queue dual-server system with optimized arrival rate in terms of average AoI and PAoI.

  • 36.
    Chen, Zhengchuan
    et al.
    Chongqing Univ, Peoples R China.
    Lang, Kang
    Chongqing Univ, Peoples R China.
    Yang, Howard H.
    Univ Illinois, IL USA; Zhejiang Univ, Peoples R China.
    Pappas, Nikolaos
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Wang, Min
    Chongqing Univ Posts & Telecommun, Peoples R China; Guilin Univ Elect Technol, Peoples R China.
    Quek, Tony Q. S.
    Singapore Univ Technol & Design, Singapore.
    Age of Information of a Dual Queue Status Update System: A Stochastic Hybrid Systems Method2023In: IEEE Communications Letters, ISSN 1089-7798, E-ISSN 1558-2558, Vol. 27, no 7, p. 1714-1718Article in journal (Refereed)
    Abstract [en]

    Using redundant devices to update the status can improve the robustness against transmission failure, thus improving timeliness of information. However, out of order update arrivals resulting from multiple devices impose a significant challenge to the analysis of timeliness of information in such systems. This letter studies the average age of information (AoI) of a dual queue status update system under zero-wait policy. We leverage tools from stochastic hybrid systems to derive closed-form expression for the average AoI of the dual queue system and extend the result to the three-queue system. The results show that the average AoI of the dual queue system can be reduced by 37.5% compared to that using only a single queue.

  • 37.
    Cheng, Jing
    et al.
    Beijing Jiaotong Univ, Peoples R China.
    Shen, Chao
    Beijing Jiaotong Univ, Peoples R China; Shenzhen Res Inst Big Data, Peoples R China.
    Chen, Zheng
    Linköping University, Department of Electrical Engineering, Communication Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Robust Beamforming Design for IRS-Aided URLLC in D2D Networks2022In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 70, no 9, p. 6035-6049Article in journal (Refereed)
    Abstract [en]

    Intelligent reflecting surface (IRS) and device-to-device (D2D) communication are two promising technologies for improving transmission reliability between transceivers in communication systems. In this paper, we consider the design of reliable communication between the access point (AP) and actuators for a downlink multiuser multiple-input single-output (MISO) system in the industrial IoT (IIoT) scenario. We propose a two-stage protocol combining IRS with D2D communication so that all actuators can successfully receive the message from AP within a given delay. The superiority of the protocol is that the communication reliability between AP and actuators is doubly augmented by the IRS-aided first-stage transmission and the second-stage D2D transmission. A joint optimization problem of active and passive beamforming is formulated, which aims to maximize the number of actuators with successful decoding. We study the joint beamforming problem for cases where the channel state information (CSI) is perfect and imperfect. For each case, we develop efficient algorithms that include convergence and complexity analysis. Simulation results demonstrate the necessity and role of IRS with a well-optimized reflection matrix, and the D2D network in promoting reliable communication. Moreover, the proposed protocol can enable reliable communication even in the presence of stringent latency requirements and CSI estimation errors.

  • 38.
    Daneshfar, Nader
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Resource Allocation with Service Availability & QoS Constraints in Mobile Fog Networks2017In: 2017 IEEE CONFERENCE ON COMPUTER COMMUNICATIONS WORKSHOPS (INFOCOM WKSHPS), IEEE , 2017, p. 1018-1019Conference paper (Refereed)
    Abstract [en]

    The evolution of the Internet of Things (IoT) is bringing Cloud services closer to the networks edge. Thus, fog networking presents itself as an approach aiming to utilize more and more resources in network edge devices to provide various networking tasks. This work presents an optimization formulation that minimizes the cost of executing a set of services, taking into account the availability of resources in mobile edge devices.

  • 39.
    Daneshfar, Nader
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Polishchuk, Valentin
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Angelakis, Vangelis
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Service Allocation in a Mobile Fog Infrastructure under Availability and QoS Constraints2018In: 2018 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM), IEEE , 2018Conference paper (Refereed)
    Abstract [en]

    The next generation of mobile networks, namely SG, together with the Internet of Things (IoT) come with a large number of delay sensitive services. To meet their requirements, cloud services are migrating to the edge of the networks to reduce latency. The notion of fog computing, where the edge plays an active role in the execution of services, comes to meet the needs for the stringent requirements. Thus, it becomes of a high importance to address the problem of mapping services demands to infrastructure resources supply. This work addresses it taking into account the randomness of resource availability in a fog infrastructure. We introduce an integer optimization formulation to minimize the total cost under a guarantee of service execution despite the uncertainty of resources availability. Our results illustrate the effect of various system parameters, such as the diversity of the infrastructure server set, the availability of different infrastructure servers in the set, and the probability of service completion required by each service.

  • 40.
    Deng, Dapeng
    et al.
    Chongqing Univ, Peoples R China.
    Chen, Zhengchuan
    Chongqing Univ, Peoples R China; Southeast Univ, Peoples R China.
    Yang, Howard H.
    Zhejiang Univ, Peoples R China.
    Pappas, Nikolaos
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Hu, Limei
    Chongqing Univ, Peoples R China.
    Wang, Min
    Chongqing Univ Posts & Telecommun, Peoples R China.
    Jia, Yunjian
    Chongqing Univ, Peoples R China.
    Quek, Tony Q. S.
    Singapore Univ Technol & Design, Singapore.
    Information Freshness in A Dual Monitoring System2022In: 2022 IEEE GLOBAL COMMUNICATIONS CONFERENCE (GLOBECOM 2022), IEEE , 2022, p. 4977-4982Conference paper (Refereed)
    Abstract [en]

    We study the average age of information (AoI) and peak AoI (PAoI) of a dual-queue status update system that monitors a common stochastic process. We capture the state transition characteristics of the considered system by establishing a Markov chain. Using the state flow graph analysis method, we derive closed-form expressions of the average peak age of information (PAoI) and the average age of information (AoI) for the dual-queue update system. The numerical results show that compared with the single-queue update system, the average PAoI of the dual-queue update system is reduced by 33.5% and the average AoI dropped by 37.5%.

  • 41.
    Dimitriou, Ioannis
    et al.
    Univ Patras, Greece.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    A Queue-based Random Access Scheme in Network-level Cooperative Wireless Networks2019In: ICC 2019 - 2019 IEEE INTERNATIONAL CONFERENCE ON COMMUNICATIONS (ICC), IEEE , 2019Conference paper (Refereed)
    Abstract [en]

    In this work, we consider a relay assisted adaptive queue-aware cooperative random access wireless network with multipacket (MPR) reception capabilities. The network consists of N sources transmitting packets to a common destination node with the aid of two relay nodes equipped with queues. The relays assist the sources by forwarding the packets that failed to reach the destination, by using a queue-based transmission control mechanism. Moreover, the relays have also their own traffic. We investigate the stability conditions and the throughput performance of the network for the full MPR channel model. Moreover, we derive expressions for the average queueing delay with the aid of the theory of boundary value problems for the asymmetric two-user network. We evaluate numerically the presented theoretical analysis.

  • 42.
    Dimitriou, Ioannis
    et al.
    Univ Patras, Greece.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    A RANDOM ACCESS G-NETWORK: STABILITY, STABLE THROUGHPUT, AND QUEUEING ANALYSIS2021In: Probability in the engineering and informational sciences (Print), ISSN 0269-9648, E-ISSN 1469-8951, Vol. 35, no 1, p. 111-137Article in journal (Refereed)
    Abstract [en]

    The effect of signals on stability, stable throughput region, and delay in a two-user slotted ALOHA-based random-access system with collisions is considered. This work gives rise to the development of random access G-networks, which can model security attacks, expiration of deadlines, or other malfunctions, and introduce load balancing among highly interacting queues. The users are equipped with infinite capacity buffers accepting external bursty arrivals. We consider both negative and triggering signals. Negative signals delete a packet from a user queue, while triggering signals cause the instantaneous transfer of packets among user queues. We obtain the exact stability region, and show that the stable throughput region is a subset of it. Moreover, we perform a compact mathematical analysis to obtain exact expressions for the queueing delay by solving a non-homogeneous Riemann boundary value problem. A computationally efficient way to obtain explicit bounds for the expected number of buffered packets at user queues is also presented. The theoretical findings are numerically evaluated and insights regarding the system performance are derived.

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  • 43.
    Dimitriou, Ioannis
    et al.
    Univ Patras, Greece.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Performance analysis of a cooperative wireless network with adaptive relays2019In: Ad hoc networks, ISSN 1570-8705, E-ISSN 1570-8713, Vol. 87, p. 157-173Article in journal (Refereed)
    Abstract [en]

    In this work, we investigate a slotted-time relay assisted cooperative random access wireless network with multipacket (MPR) reception capabilities. MPR refers to the capability of a wireless node to successfully receive packets from more than two other modes that transmit simultaneously at the same slot. We consider a network of N saturated sources that transmit packets to a common destination node with the cooperation of two infinite capacity relay nodes. The relays assist the sources by forwarding the packets that failed to reach the destination. Moreover, the relays have also packets of their own to transmit to the destination. We further assume that the relays employ a state-dependent retransmission control mechanism. In particular, a relay node accordingly adapts its transmission probability based on the status of the other relay. Such a protocol is towards self-aware networks and leads to substantial performance gains in terms of delay. We investigate the stability region and the throughput performance for the full MPR model. Moreover, for the asymmetric two-sources, two-relay case we derive the generating function of the stationary joint queue-length distribution with the aid of the theory of boundary value problems. For the symmetric case, we obtain explicit expressions for the average queueing delay in a relay node without solving a boundary value problem. Extensive numerical examples are presented and provide insights on the system performance. (C) 2018 Elsevier B.V. All rights reserved.

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  • 44.
    Dimitriou, Ioannis
    et al.
    Department of Mathematics, University of Patras, 26500, Patras, Greece.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Performance Analysis of an Adaptive Queue-Aware Random Access Scheme with Random Traffic2018In: 2018 IEEE International Conference on Communications (ICC) Proceedings Kansas City, MO, USA 20–24 May 2018, IEEE Communications Society, 2018, p. 1-6Conference paper (Refereed)
    Abstract [en]

    In this work, we consider an adaptive two-user random access scheme with multipacket reception (MPR) ca- pabilities. A user adapts its transmission characteristics based on the status of the other user. The users have external random traffic stored in their queues. We derive the stable throughput region of the system and the convexity conditions of this region. We derive analytically the queueing delay by formulating and solving a Riemann-Hilbert boundary value problem. Finally, we evaluate numerically the presented theoretical results. 

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    Performance Analysis of an Adaptive Queue-Aware Random Access Scheme with Random Traffic
  • 45.
    Dimitriou, Ioannis
    et al.
    Univ Patras, Greece.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Stability and Delay Analysis of an Adaptive Channel-Aware Random Access Wireless Network2017In: ANALYTICAL AND STOCHASTIC MODELLING TECHNIQUES AND APPLICATIONS, ASMTA 2017, SPRINGER INTERNATIONAL PUBLISHING AG , 2017, Vol. 10378, p. 63-80Conference paper (Refereed)
    Abstract [en]

    In this work, we consider an asymmetric two-user random access wireless network with interacting nodes, time-varying links and multipacket reception capabilities. The users are equipped with infinite capacity buffers where they store arriving packets that will be transmitted to a destination node. Moreover, each user employs a general transmission control protocol under which, it adapts its transmission probability based both on the state of the other user, and on the channel state information according to a Gilbert-Elliot model. We study a two-dimensional discrete time Markov chain, investigate its stability condition, and show that its steady state performance is expressed in terms of a solution of a Riemann-Hilbert boundary value problem. Moreover, for the symmetrical system, we provide closed form expressions for the average delay at each user node. Numerical results are obtained and show insights in the system performance.

  • 46.
    Dimitriou, Ioannis
    et al.
    Department of Mathematics, University of Patras, Greece.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Stable Throughput and Delay Analysis of a Random Access Network With Queue-Aware Transmission2018In: IEEE Transactions on Wireless Communications, ISSN 1536-1276, E-ISSN 1558-2248, Vol. 17, no 5, p. 3170-3184Article in journal (Refereed)
    Abstract [en]

    In this work we consider a two-user and a three-user slotted ALOHA network with multi-packet reception (MPR) capabilities and a queue-aware transmission control. In this setting, the nodes can adapt their transmission probabilities and their transmission parameters based on the status of the other nodes. Each user has external bursty arrivals that are stored in their infinite capacity queues. We focus on the fundamental problem of characterizing the stable throughput region, as well as of investigating the queueing delay. For the two- and the three-user cases we obtain the exact stability region, whereas in the former case we also provide the conditions under which the stability region is a convex set. We perform a detailed mathematical analysis to study the queueing delay in the two-user case by formulating two boundary value problems, the solution of which provide the generating function of the joint stationary probability distribution of the queue size at user nodes. Furthermore, for the two-user symmetric case with MPR we obtain a lower and an upper bound for the average delay without the need of solving a boundary value problem. In addition, we provide a closed form expression for the gap between the lower and the upper bound. The bounds as it is seen in the numerical results appear to be tight. Explicit expressions for the average delay are obtained for the symmetrical model with capture effect. We also provide a closed form expression for the optimal transmission probability that minimizes the average delay in the symmetric capture case. Finally, we evaluate numerically the presented theoretical results.

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  • 47.
    Fountoulakis, Emmanouil
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering. Ericsson AB, Sweden.
    Charalambous, Themistoklis
    Univ Cyprus, Cyprus.
    Ephremides, Anthony
    Univ Maryland, MD 20742 USA.
    Pappas, Nikolaos
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Scheduling Policies for AoI Minimization With Timely Throughput Constraints2023In: IEEE Transactions on Communications, ISSN 0090-6778, E-ISSN 1558-0857, Vol. 71, no 7, p. 3905-3917Article in journal (Refereed)
    Abstract [en]

    In 5G and beyond communication systems, the notion of latency gets great momentum in wireless connectivity as a metric for serving real-time communications requirements. However, in many applications, research has pointed out that latency could be inefficient to handle applications with data freshness requirements. Recently, Age of Information (AoI) metric, which can capture the freshness of the data, has attracted a lot of attention. In this work, we consider mixed traffic with time-sensitive users; a deadline-constrained user, and an AoI-oriented user. To develop an efficient scheduling policy, we cast a novel optimization problem formulation for minimizing the average AoI while satisfying the timely throughput constraints. The formulated problem is cast as a Constrained Markov Decision Process (CMDP). We relax the constrained problem to an unconstrained Markov Decision Process (MDP) problem by utilizing the Lyapunov optimization theory and it can be proved that it is solved per frame by applying backward dynamic programming algorithms with optimality guarantees. In addition, we provide a low-complexity algorithm guaranteeing that the timely-throughput constraint is satisfied. Simulation results show that the timely throughput constraints are satisfied while minimizing the average AoI. Simulation results show the convergence of the algorithms for different values of the weighted factor and the trade-off between the AoI and the timely throughput.

  • 48.
    Fountoulakis, Emmanouil
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Charalambous, Themistoklis
    Aalto Univ, Finland.
    Nomikos, Nikolaos
    Univ Cyprus, Cyprus.
    Ephremides, Anthony
    Univ Maryland, MD 20742 USA.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Information Freshness and Packet Drop Rate Interplay in a Two-User Multi-Access Channel2021In: 2020 IEEE INFORMATION THEORY WORKSHOP (ITW), IEEE , 2021Conference paper (Refereed)
    Abstract [en]

    In this work, we combine the two notions of timely delivery of information to study their interplay; namely, deadline-constrained packet delivery due to latency constraints and freshness of information. More specifically, we consider a two-user multiple access setup with random-access, in which user 1 is a wireless device with a queue and has external bursty traffic which is deadline-constrained, while user 2 monitors a sensor and transmits status updates to the destination. We provide analytical expressions for the throughput and drop probability of user 1, and an analytical expression for the average Age of Information (AoI) of user 2 monitoring the sensor. The relations reveal that there is a trade-off between the average AoI of user 2 and the drop rate of user 1: the lower the average AoI, the higher the drop rate, and vice versa. Simulations corroborate the validity of our theoretical results.

  • 49.
    Fountoulakis, Emmanouil
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Charalambous, Themistoklis
    Aalto Univ, Finland.
    Nomikos, Nikolaos
    Univ Cyprus, Cyprus.
    Ephremides, Anthony
    Univ Maryland, MD 20742 USA.
    Pappas, Nikolaos
    Linköping University, Department of Computer and Information Science, Database and information techniques. Linköping University, Faculty of Science & Engineering.
    Information Freshness and Packet Drop Rate Interplay in a Two-User Multi-Access Channel2022In: Journal of Communications and Networks, ISSN 1229-2370, E-ISSN 1976-5541, Vol. 24, no 3, p. 357-364Article in journal (Refereed)
    Abstract [en]

    In this work, we combine the two notions of timely delivery of information to study their interplay; namely, deadline -constrained packet delivery due to latency constraints and freshness of information. More specifically, we consider a two -user multiple access setup with random access, in which user 1 is a wireless device with a buffer and has external bursty traffic which is deadline-constrained, while user 2 monitors a sensor and transmits status updates to the destination. We provide analytical expressions for the throughput and drop probability of user 1. For user 2, we derive in closed form the age of information distribution, the average age of information (AoI), and the probability the AoI to be larger than a certain value for each time slot. The relations reveal a trade-off between the average AoI of user 2 and the drop rate of user 1: the lower the average AoI, the higher the drop rate, and vice versa. Simulations corroborate the validity of our theoretical results.

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  • 50.
    Fountoulakis, Emmanouil
    et al.
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    Liao, Qi
    End-to-End Network & Service Automation Lab, Nokia Bell Labs, Stuttgart, Germany.
    Pappas, Nikolaos
    Linköping University, Department of Science and Technology, Communications and Transport Systems. Linköping University, Faculty of Science & Engineering.
    An End-to-End Performance Analysis for Service Chaining in a Virtualized Network2020In: IEEE Open Journal of the Communications Society, E-ISSN 2644-125X, Vol. 1, p. 148-163Article in journal (Refereed)
    Abstract [en]

    Future mobile networks supporting Internet of Things are expected to provide both high throughput and low latency to user-specific services. One way to overcome this challenge is to adopt Network Function Virtualization (NFV) and Multi-access Edge Computing (MEC). Besides latency constraints, these services may have strict function chaining requirements. The distribution of network functions over different hosts and more flexible routing caused by service function chaining raise new challenges for end-to-end performance analysis. In this paper, as a first step, we analyze an end-to-end communication system that consists of both MEC servers and a server at the core network hosting different types of virtual network functions. We develop a queueing model for the performance analysis of the system consisting of both processing and transmission flows. We propose a method in order to derive analytical expressions of the performance metrics of interest, i.e., end-to-end delay, system throughput, task drop rate. Then, we show how to apply the similar method to a larger system and derive a stochastic model for such systems. We observe that the simulation and analytical results are very close. By evaluating the system under different scenarios, we provide insights for the decision making on traffic flow control and its impact on critical performance metrics.

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