Search results for "Computer network"

2015

High-throughput detection of protein interactions has had a major impact in our understanding of the intricate molecular machinery underlying the living cell, and has permitted the construction of very large protein interactomes. The protein networks that are currently available are incomplete and a significant percentage of their interactions are false positives. Fortunately, the structural properties observed in good quality social or technological networks are also present in biological systems. This has encouraged the development of tools, to improve the reliability of protein networks and predict new interactions based merely on the topological characteristics of their components. Sinc…

Cooperative communication design with distributed code allocation in a clustered network

2011

A major challenge for cooperative communication in distributed networks is to coordinate relay transmissions without introducing too much overhead. Targeting a clustered network, we propose a novel cooperative communication scheme including channel quality based relay selection and distributed space-time code allocation in this paper. Both analysis and simulations are carried out to investigate the performance of the proposed cooperative scheme, in terms of packet delivery rate, throughput and energy efficiency, under different channel conditions and network density.

A trust-based security enforcement in disruption-tolerant networks

2017

We propose an approach to enforce security in disruption- and delay-tolerant networks (DTNs) where long delays, high packet drop rates, unavailability of central trusted entity etc. make traditional approaches unfeasible. We use trust model based on subjective logic to continuously evaluate trustworthiness of security credentials issued in distributed manner by network participants to deal with absence of centralised trusted authorities.

Designing Frame Relay WAN Networks with Trade-Off between Link Cost and Performance

2014

This paper is focused on the problem of designing a Wide Area Network topology with trade-off between link cost and response time to users. The L2 technology chosen for the research is a Frame Relay based solution. The link capacities in the network and the routes used by packets are determined in a way to minimize network cost and response time at the same time. In FR networks link capacity corresponds directly to CIR parameter which makes the presented numerical results very useful in practice, especially during preliminary network design in the Design Phase of the PPDIOO methodology.

Dynamic packet scheduling performance in UTRA Long Term Evolution downlink

2008

In this paper we evaluate the performance of dynamic Packet Scheduling (PS) of 3GPP UTRAN Long Term Evolution (LTE) Downlink. Packet scheduling is of utmost importance in 3G LTE, because all traffic types with different Quality of Service requirements are competing of the resources. We present a decoupled time and frequency domain packet scheduling framework for LTE downlink. Simulation results with three basic packet scheduler combinations with different amount of fairness are presented in four different 3GPP macro simulation cases to show the both extremes in tradeoff between fairness and spectral efficiency. In addition, the effect of multiuser diversity on packet scheduling performance …

Feasibility of FPGA accelerated IPsec on cloud

2018

Abstract Hardware acceleration for famous VPN solution, IPsec, has been widely researched already. Still it is not fully covered and the increasing latency, throughput, and feature requirements need further evaluation. We propose an IPsec accelerator architecture in an FPGA and explain the details that need to be considered for a production ready design. This research considers the IPsec packet processing without IKE to be offloaded on an FPGA in an SDN network. Related work performance rates in 64 byte packet size for throughput is 1–2 Gbps with 0.2 ms latency in software, and 1–4 Gbps with unknown latencies for hardware solutions. Our proposed architecture is capable to host 1000 concurre…

On the role of symmetry in solving maximum lifetime problem in two-dimensional sensor networks

2016

We analyze a continuous and discrete symmetries of the maximum lifetime problem in two dimensional sensor networks. We show, how a symmetry of the network and invariance of the problem under a given transformation group $G$ can be utilized to simplify its solution. We prove, that for a $G$-invariant maximum lifetime problem there exists a $G$-invariant solution. Constrains which follow from the $G$-invariance allow to reduce the problem and its solution to a subset, an optimal fundamental region of the sensor network. We analyze in detail solutions of the maximum lifetime problem invariant under a group of isometry transformations of a two dimensional Euclidean plane.

Priority Levels Based Multi-hop Broadcasting Method for Vehicular Ad hoc Networks

2015

International audience; This paper deals with broadcasting problem in vehicular ad hoc networks (VANETs). This communication mode is commonly used for sending safety messages and traffic information. However, designing an efficient broadcasting protocol is hard to achieve since it has to take into account some parameters related to the network environment, for example, the network density, in order to avoid causing radio interferences. In this paper, we propose a novel Autonomic Dissemination Method (ADM) which delivers messages in accordance with given priority and density levels. The proposed approach is based on two steps: an offline optimization process and an adaptation to the network …

Downlink channel access performance of NR-U: Impact of numerology and mini-slots on coexistence with Wi-Fi in the 5 GHz band

2020

Coexistence between cellular systems and Wi-Fi gained the attention of the research community when LTE License Assisted Access (LAA) entered the unlicensed band. The recent introduction of NR-U as part of 5G introduces new coexistence opportunities because it implements scalable numerology (flexible subcarrier spacing and OFDM symbol lengths), and non-slot based scheduling (mini-slots), which considerably impact channel access. This paper analyzes the impact of NR-U settings on its coexistence with Wi-Fi networks and compares it with LAA operation using simulations and experiments. First, we propose a downlink channel access simulation model, which addresses the problem of the dependency an…

On Constructing Persistent Identifiers with Persistent Resolution Targets

2016

Persistent Identifiers (PID) are the foundation referencing digital assets in scientific publications, books, and digital repositories. In its realization, PIDs contain metadata and resolving targets in form of URLs that point to data sets located on the network. In contrast to PIDs, the target URLs are typically changing over time; thus, PIDs need continuous maintenance -- an effort that is increasing tremendously with the advancement of e-Science and the advent of the Internet-of-Things (IoT). Nowadays, billions of sensors and data sets are subject of PID assignment. This paper presents a new approach of embedding location independent targets into PIDs that allows the creation of maintena…