Heterogeneous and opportunistic wireless networks

Recent years have witnessed the evolution of a large plethora of wireless technologies with different characteristics, as a response of the operators' and users' needs in terms of an efficient and ubiquitous delivery of advanced multimedia services. The wireless segment of network infrastructure has penetrated in our lives, and wireless connectivity has now reached a state where it is considered to be an indispensable service as electricity or water supply. Wireless data networks grow increasingly complex as a multiplicity of wireless information terminals with sophisticated capabilities get embedded in the infrastructure. © 2012 Springer Milan. All Right Reserved

GSAF: efficient and flexible geocasting for opportunistic networks

With the proliferation of smartphones and their advanced connectivity capabilities, opportunistic networks have gained a lot of traction during the past years; they are suitable for increasing network capacity and sharing ephemeral, localised content. They can also offload traffic from cellular networks to device-to-device ones, when cellular networks are heavily stressed. Opportunistic networks can play a crucial role in communication scenarios where the network infrastructure is inaccessible due to natural disasters, large-scale terrorist attacks or government censorship. Geocasting, where messages are destined to specific locations (casts) instead of explicitly identified devices, has a large potential in real world opportunistic networks, however it has attracted little attention in the context of opportunistic networking. In this paper we propose Geocasting Spray And Flood (GSAF), a simple but efficient and flexible geocasting protocol for opportunistic, delay-tolerant networks. GSAF follows a simple but elegant and flexible approach where messages take random walks towards the destination cast. Messages that follow directions away from the cast are extinct when the device buffer gets full, freeing space for new messages to be delivered. In GSAF, casts do not have to be pre-defined; instead users can route messages to arbitrarily defined casts. Our extensive evaluation shows that GSAF is efficient, in terms of message delivery ratio and latency as well as network overhead

On the feasibility of a user-operated mobile content distribution network

The vast majority of mobile data transfers today follow the traditional client-server model. Although in the fixed network P2P approaches have been exploited and shown to be very efficient, in the mobile domain there has been limited attempt to leverage on P2P (D2D) for large-scale content distribution (i.e., not DTN-like, point-to-point message transfers). In this paper, we explore the potential of a user-operated, smartphone-centric content distribution model for smartphone applications. In particular, we assume source nodes that are updated directly from the content provider (e.g., BBC, CNN), whenever updates are available; destination nodes are then directly updated by source nodes in a D2D manner. We leverage on sophisticated information-aware and application-centric connectivity techniques to distribute content between mobile devices in densely-populated urban environments. Our target is to investigate the feasibility of an opportunistic content distribution network in an attempt to achieve widespread distribution of heavy content (e.g., video files) to the majority of the destination nodes. We propose ubiCDN as a ubiquitous, user-operated and distributed CDN for mobile applications

An Analysis of Data Quality Defects in Podcasting Systems

Podcasting has emerged as an asynchronous delay-tolerant method for the distribution of multimedia files through a network. Although podcasting has become a popular Internet application, users encounter frequent information quality problems in podcasting systems. To better understand the severity of these quality problems, we have applied the Total Data Quality Management methodology to podcasting. Through the application of this methodology we have quantified the data quality problems inherent within podcasting metadata, and performed an analysis that maps specific metadata defects to failures in popular commercial podcasting platforms. Furthermore, we extracted the Really Simple Syndication (RSS) feeds from the iTunes catalog for the purpose of performing the most comprehensive measurement of podcasting metadata to date. From these findings we attempted to improve the quality of podcasting data through the creation of a metadata validation tool - PodCop. PodCop extends existing RSS validation tools and encapsulates validation rules specific to the context of podcasting. We believe PodCop is the first attempt at improving the overall health of the podcasting ecosyste

An Analysis of Data Quality Defects in Podcasting Systems

Podcasting has emerged as an asynchronous delay-tolerant method for the distribution of multimedia files through a network. Although podcasting has become a popular Internet application, users encounter frequent information quality problems in podcasting systems. To better understand the severity of these quality problems, we have applied the Total Data Quality Management methodology to podcasting. Through the application of this methodology we have quantified the data quality problems inherent within podcasting metadata, and performed an analysis that maps specific metadata defects to failures in popular commercial podcasting platforms. Furthermore, we extracted the Really Simple Syndication (RSS) feeds from the iTunes catalog for the purpose of performing the most comprehensive measurement of podcasting metadata to date. From these findings we attempted to improve the quality of podcasting data through the creation of a metadata validation tool - PodCop. PodCop extends existing RSS validation tools and encapsulates validation rules specific to the context of podcasting. We believe PodCop is the first attempt at improving the overall health of the podcasting ecosyste

An Analysis of Data Quality Defects in Podcasting Systems

Podcasting has emerged as an asynchronous delay-tolerant method for the distribution of multimedia files through a network. Although podcasting has become a popular Internet application, users encounter frequent information quality problems in podcasting systems. To better understand the severity of these quality problems, we have applied the Total Data Quality Management methodology to podcasting. Through the application of this methodology we have quantified the data quality problems inherent within podcasting metadata, and performed an analysis that maps specific metadata defects to failures in popular commercial podcasting platforms. Furthermore, we extracted the Really Simple Syndication (RSS) feeds from the iTunes catalog for the purpose of performing the most comprehensive measurement of podcasting metadata to date. From these findings we attempted to improve the quality of podcasting data through the creation of a metadata validation tool - PodCop. PodCop extends existing RSS validation tools and encapsulates validation rules specific to the context of podcasting. We believe PodCop is the first attempt at improving the overall health of the podcasting ecosyste

Articles indexats publicats per investigadors del Campus de Terrassa: 2013

Aquest informe recull els 228 treballs publicats per 177 investigadors/es del Campus de Terrassa en revistes indexades al Journal Citation Report durant el 2013Preprin

Annual Research Report, 2009-2010

Annual report of collaborative research projects of Old Dominion University faculty and students in partnership with business, industry and governmenthttps://digitalcommons.odu.edu/or_researchreports/1001/thumbnail.jp

Annual Research Report, 2010-2011

Annual report of collaborative research projects of Old Dominion University faculty and students in partnership with business, industry and government.https://digitalcommons.odu.edu/or_researchreports/1000/thumbnail.jp

Спосіб передачі даних у високонавантажених мобільних мережах

Актуальність теми. Мобільний зв'язок є невід’ємною частиною нашого теперішнього життя. Чимало речей у нашому житті так чи інакше пов’язані з використання мобільного пристрою. Але телефон майже не несе користі якщо використовувати його без мобільного зв’язку. Тому надзвичайно важливою характеристикою мобільного зв’язку є його якість. Одним з показників якості є стабільність, що характеризує можливість у будь який момент часу отримати доступ до мережі. Зазвичай якість мобільного зв’язку є прийнятною та задовольняє більшість потреб користувачів. Проте існують ситуації, коли базові станції мобільного зв’язку не витримують великої кількості користувачів і через це якість з’єднання суттєво погіршується. В таких випадках навіть коротке текстове повідомлення може передаватися протягом декількох хвилин. Така проблема є характерною під час масових скупчень людей, наприклад, на концертах, фестивалях або ярмарках. Метою роботи є покращення способу передачі даних у мобільній мережі з використанням алгоритму, який зможе зменшити надлишкове навантаження мережі без потреби модифікації існуючого обладнання. Об’єктом дослідження є мережі стільникового зв’язку та методи обміну даними між мобільними пристроями. Предметом дослідження є характеристика навантаження стільникової мережі, проблеми що пов’язані з перевантаженням та методи вирішення надлишкового навантаження мережі. Методи дослідження. Моделювання роботи мережі з можливістю зміни основних параметрів мережі, що стосуються досліду, та відстеження показників мережі у кожен момент часу. Наукова новизна полягає у створенні способу передачі даних у мережі, що дозволяє зменшити надлишкове навантаження мережі без значної втрати у швидкості передачі даних, і при цьому, без потреби змін у апаратному забезпеченні. Практична цінність полягає у пришвидшені передачі даних у високонавантажених мережах при незначних ресурсних затратах як з боку користувача так і з боку поставника послуг передачі даних. Структура та обсяг роботи. Магістерська дисертація складається з вступу, чотирьох розділів, висновків та додатків. У вступі представлена загальна характеристика проблеми, обґрунтована необхідність розробки нового алгоритму, сформульована задача роботи. У першому розділі дається визначення стільникової мережі та описані основні характеристики роботи стільникової мережі. У другому розділі описані можливі проблеми, дається визначення високонавантажених мереж, та проведена оцінка існуючих рішень та їх недоліків. У третьому розділі наведено покращений спосіб передачі даних у високонавантажених мережах, описані переваги на недоліки. У четвертому розділі, наведено приклад роботи алгоритму на різних наборах даних, та проведений аналіз результатів. У висновках описано результати дослідження.Actuality of theme. Mobile communications are an integral part of our lives today. Many things in our lives are related to the use of a mobile device in one way or another. But the phone is almost useless if you use it without a mobile connection. Therefore, the quality of mobile communication is an extremely important characteristic. One of the indicators of quality is stability, which characterizes the ability to access the network at any time. Mobile quality is generally acceptable and meets most user needs. However, there are situations where mobile base stations do not withstand a large number of users and as a result, the quality of the connection deteriorates significantly. In such cases, even a short text message can be transmitted within minutes. This problem is typical during mass gatherings, such as concerts, festivals or fairs. The aim of the work is to improve the method of data transmission in the mobile network using an algorithm that can reduce the overload of the network without the need to modify existing equipment. The object of research is cellular networks and methods of data exchange between mobile devices. The subject of the study is the characteristics of the load on the cellular network, the problems associated with congestion and methods of solving the overload of the network. Research methods. Simulation of network operation with the ability to change the basic parameters of the network related to the experiment, and tracking network performance at any time. The scientific novelty is to create a method of data transmission in the network, which reduces the overload of the network without a significant loss in data rate, and without the need for changes in hardware. The practical value lies in the accelerated data transfer in high-load networks at low resource costs both by the user and by the data service provider. Structure and scope of work. The master's dissertation consists of an introduction, four chapters, conclusions and appendices. The introduction presents the general characteristics of the problem, substantiates the need to develop a new algorithm, formulates the task. The first section defines the cellular network and describes the main characteristics of the cellular network. The second section describes possible problems, identifies high-load networks, and assesses existing solutions and their shortcomings. The third section presents an improved method of data transmission in high-load networks, describes the advantages and disadvantages. In the fourth section, an example of the algorithm on different data sets is given, and the results are analyzed. The conclusions describe the results of the study