Search results for "Computer network"
showing 10 items of 1634 documents
Performance Evaluation of a new Adaptive Packet Marking Scheme for TCP over DiffServ Networks
2004
In differentiated services (DiffServ) networks, packets may receive a different treatment according to their differentiated services code point (DSCP) label. As a consequence, packet marking schemes can be devised to differentiate packets belonging to the same TCP flow, with the goal of improving the experienced performance. The paper presents an extensive performance evaluation of a new adaptive packet marking scheme, applied to a traffic scenario composed of TCP flows with different lengths. The proposed marking scheme is most efficient when applied to a scenario composed of all long-lived flows. In a realistic mixed traffic scenario, composed of both long-lived and short-lived TCP flows,…
Priority-based initial access for URLLC traffic in massive IoT networks: Schemes and performance analysis
2020
Abstract At a density of one million devices per square kilometer, the10’s of billions of devices, objects, and machines that form a massive Internet of things (mIoT) require ubiquitous connectivity. Among a massive number of IoT devices, a portion of them require ultra-reliable low latency communication (URLLC) provided via fifth generation (5G) networks, bringing many new challenges due to the stringent service requirements. Albeit a surge of research efforts on URLLC and mIoT, access mechanisms which include both URLLC and massive machine type communications (mMTC) have not yet been investigated in-depth. In this paper, we propose three novel schemes to facilitate priority-based initial …
Optimal Buffer Resource Allocation in Wireless Caching Networks
2019
Wireless caching systems have been exhaustively investigated in recent years. Due to limited buffer capacity, and unbalanced arrival and service rates, the backlogs may exist in the caching node and even cause buffer overflow. In this paper, we first investigate the relationship among backlogs, buffer capacity, data arrival rate and service rate, utilizing the martingale theory which is flexible in handling any arrival and service processes. Then given a target buffer overflow probability, the minimal required buffer portion is determined. If the devoted buffer capacity can fulfill all serving users' minimal buffer requirements, an optimization problem is constructed with the objective to m…
Performance analysis of the out-of-band signaling scheme for high speed wireless LANs
2005
In this paper, we study the performance of our earlier proposed out-of-band signaling (OBS) scheme for high speed wireless local area networks (WLANs). We employ the system approximation technique for modeling of the OBS scheme. An equivalent state dependent single server queue, that describes the OBS scheme, is constructed for the analysis of the throughput and delay performances. Moreover, we study the throughput optimization of the OBS scheme, which provides a means for optimizing the performance of the OBS scheme, given a particular network environment. Finally, we conduct several simulation experiments to validate our analytical results.
Call Admission Control in Single and Two-Tier Cellular Networks
2010
We consider four strategies for call admission control (CAC) in single and two-tier cellular networks, which are designed to ensure advantage of handover calls: dynamic redundancy (cutoff priority scheme), partial dynamic redundancy (fractional guard channel scheme), static redundancy (rigid division-based CAC scheme) and restriction of the number of new calls admitted (new call bounding scheme). We show the advantage of dynamic reservation by numerical analysis. We strictly prove it in the case of two-channel system with losses.
Secure and efficient data storage in unattended wireless sensor networks
2009
©2009 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. Article also available from publisher: http://dx.doi.org/10.1109/NTMS.2009.5384753 Providing forward and backward secrecy is still a big challenge in Unattended Wireless Sensor Networks (UWSNs), though some storage schemes have been proposed. Additionally, high storage requirement needs efficient storage techniques. In this paper, we propose a novel homomorphic…
No Reservations Required: Achieving Fairness between Wi-Fi and NR-U with Self-Deferral Only
2021
Wireless technologies coexisting in unlicensed bands should receive a fair share of the available channel resources, even when they use different access methods. We consider the problem of coexistence between Wi-Fi and New Radio Unlicensed (NR-U) nodes, which employ, respectively, a random and scheduled access scheme. The latter typically resorts to reservation signals (RSs), which allow keeping the control of the channel until the start of the next synchronized slot. This mechanism, although effective for increasing the channel access opportunities of scheduled-based nodes, is also a waste of channel resources. We investigate alternative solutions, based on self-deferral only. We built ana…
Multi-cloud privacy preserving schemes for linear data mining
2015
This paper presents an approach to privacy-preserving data mining that relies upon a relatively simple secret sharing scheme. Its main feature is that users, sensitive data owners, are engaged in the secret sharing operations that protect their privacy. They are grouped in independent clouds connected to a central unit, the data miner, that only manages the aggregated data of each cloud, therefore avoiding the disclosure of information belonging to single nodes. We propose two privacy preserving schemes, with different privacy levels and communication costs. When designing them, we assume that some users' data might become inaccessible during the operation of the privacy preserving protocol…
User Evaluation of the Smartphone Screen Reader VoiceOver with Visually Disabled Participants
2018
Touchscreen assistive technology is designed to support speech interaction between visually disabled people and mobile devices, allowing hand gestures to interact with a touch user interface. In a global perspective, the World Health Organisation estimates that around 285 million people are visually disabled with 2/3 of them over 50 years old. This paper presents the user evaluation of VoiceOver, a built-in screen reader in Apple Inc. products, with a detailed analysis of the gesture interaction, familiarity and training by visually disabled users and the system response. Six participants with prescribed visual disability took part in the tests in a usability laboratory under controlled con…
The Cyberspace Threats and Cyber Security Objectives in the Cyber Security Strategies
2013
Threats in cyberspace can be classified in many ways. This is evident when you look at cyber security on a multinational level. One of the most common models is a threefold classification based on motivational factors. Most nations use this model as a foundation when creating a strategy to handle cyber security threats as it pertains to them. This paper will use the five level model: cyber activism, cybercrime, cyber espionage, cyber terrorism and cyber warfare. The National Cyber Security Strategy defines articulates the overall aim and objectives of the nation's cyber security policy and sets out the strategic priorities that the national government will pursue to achieve these objectives…