Search results for "Computer network"

Blockchain based Inter-domain Latency Aware Routing Proposal in Software Defined Network

2018

Border gateway protocol (BGP) version 4 is routing current Internet for more than 20 years. BGP is the only protocol that has proven its routing capability of such size network with continually growing nature. Although BGP is scalable and network layer reachability information it lacks quality of service metrics like latency. BGP routing decision algorithm uses as-path length between autonomous systems (AS) as main factor for most of its best-path calculations. Because of more affordable peering architectures as-path length is generally decreasing in worldwide internet network resulting in less efficient routes for real-time internet protocol traffic. This study proposes future internet arc…

Wireless communication based on Raspberry pi and Codesys for mobile robots using IoT technology

2021

The industrial environment is going through exponential changes, due to the diversity of technological solutions that appear more and more frequently and the increase of productivity at increasing capacities. Due to this fact in the industrial area the number of devices, processing systems, collaborative robots, mobile robots and industrial equipment is increasing more and more. Consequently, there is a need for communication and connectivity of entities, common physical or virtual functioning and decision making, all of which are fundamental to the transition to the new concept of Industry 4.0. This study presents how wireless communication can be achieved in a mobile robotic platform that…

The Valencia Port Authority (VPA): environmental information in the annual report

2012

In recent years, most companies are participating in the disclosing of information on the impact of their potential activities on the environment. In 2002, Spain developed its legislation on environmental information in annual reports. The port industry has a potential environmental and economic impact. In this context, it is important to know how it disclosure environmental information in the annual reports. The case of study shows the disclosure information characteristics of Valencia Port Authority (VPA) and the relationships with the environment. The results concluded that VPA has adapted its information not only the standards but as a mean of legitimation.

A Bayesian Learning Automata-Based Distributed Channel Selection Scheme for Cognitive Radio Networks

2014

We consider a scenario where multiple Secondary Users SUs operate within a Cognitive Radio Network CRN which involves a set of channels, where each channel is associated with a Primary User PU. We investigate two channel access strategies for SU transmissions. In the first strategy, the SUs will send a packet directly without operating Carrier Sensing Medium Access/Collision Avoidance CSMA/CA whenever a PU is absent in the selected channel. In the second strategy, the SUs implement CSMA/CA to further reduce the probability of collisions among co-channel SUs. For each strategy, the channel selection problem is formulated and demonstrated to be a so-called "Potential" game, and a Bayesian Lea…

Trust-based framework for security enhancement of P2PSIP communication systems

2009

Today, Peer-to-Peer SIP based communication systems have attracted much attention from both academia and industry. The decentralized nature of P2P might provide the distributed peer-to-peer communication system without help of the traditional SIP server. However, it comes to the cost of reduced trustworthiness and may cause security problems, e.g. privacy leaks, unpredictable availability, etc. In this paper, we investigate on P2PSIP security issues and propose a subjective based trust model that offers trust services during P2PSIP session establishment. The main issues considered in this model include opinion calculation, opinion maintenance, data confidentiality and integrity, message rou…

Demo - Dynamic Adaptations of WiFi Channel Widths Without TX/RX Coordination

2017

Most modern standards for wireless communications support physical layer adaptations, in terms of dynamic selection of channel central frequency, transmission power, modulation format, etc., in order to increase link robustness under time-varying propagation and interference conditions. In this demo, we demonstrate that another powerful solution for extending physical layer flexibility in OFDM-based technologies is the dynamic adaptation of the channel width. Although some standards already define the possibility of utilizing multiple channel widths (e.g. 20MHz, 10MHz, 5MHz for IEEE 802.11a standards), such an utilization is limited to a static configuration of a value defined during the ne…

Side Effects of Ambient Noise Immunity Techniques on Outdoor IEEE 802.11 Deployments

2008

A very common conclusion of many experimental studies about IEEE 802.11 outdoor network deployments is that their poor performance results derive from the unfavorable interference and multi-path signals in which the WLAN-cards are required to operate. Goal of this paper is to show that this condition does not always hold, and unexpected and inaccurated PHY layer implementations can be a primary cause of packet losses. With the support of extensive measurement campaigns led in our campus, we provide the performance evidence that IEEE 802.11 outdoor performance impairments are strongly affected by proprietary interference mitigation techniques that adaptively adjust the WLAN-card receiver sen…

Two-Step Flow of Communication

2008

New client puzzle approach for DoS resistance in ad hoc Networks

2010

In this paper we propose a new client puzzle approach to prevent Denial of Service (DoS) attacks in ad hoc networks. Each node in the network first solves a computational problem and with the solution has to create and solve a client puzzle. By combining computational problems with puzzles, we improve the efficiency and latency of the communicating nodes and resistance in DoS attacks. Experimental results show the effectiveness of our approach.

1 Hop or 2 hops: Topology analysis in Body Area Network

2014

Wireless Body Area Networks (WBANs) have recently received much attention due to the possibility to be used in healthcare applications. For these applications, link reliability and energy efficiency are critical issues, as in many cases, information carried can be vital for the patient and batteries cannot be easily replaced. The wireless on-body channel experiences significant temporal variation due to body movements and the use of relays is sometimes necessary in order to guarantee reliability or improve lifetime. In this paper, an experimental evaluation is used to give a better understanding about reliability, energy consumption and lifetime in a single hop or a two hops communication. …