Wifi localization as a network service

In last years, many efforts have been made to build indoor positioning systems using different types of signals and different types of position algorithms. Experiences with sound, light, infra-red, Bluetooth and popular IEEE 802.11 network signals have been carried out both by commercial and academic entities. The major goal is to fulfill the lack of GPS coverage inside buildings with a more precise and/or cheaper alternative. WiFi based Localization systems gain special attention in this context due to its huge usage inside all modern facilities. Many algorithms have been proposed to estimate the device position within the WiFi network using the signal strengths (RSS) obtained by 802.11 device drivers. RSS values can be registered by each packet received, either by the the user’s device or by the network’s Access Points. Values can then be compared with a pre-configured map of signal strengths obtained in a calibration (offline) phase. This paper presents a localization system, where the location is determined exclusively by the network infrastructure. The location computation is based on the signal strength measured at Access Points and sent to a localization server. The localization server determines the location, stores it in a database and accepts requests from authenticated clients. Results obtained in experimental tests are discussed and compared with those published by other authors, allowing us to conclude that the system combines a good accuracy, with the advantage of not requiring any intervention from clients in the localization process. The entire system is designed in order to make locations available as a network service

Encaminhamento inter-domínio com qualidade de serviço

Para dotar o encaminhamento Inter-domínio, baseado no BGP, da capacidade de determinar caminhos dependendo dos requisitos de Qualidade de Serviço do tráfego fim a fim, torna-se fundamental incorporar métricas de QoS nas mensagens BGP trocadas entre os Routers Fronteira dos Sistemas Autónomos (AS). Esta proposta apresenta a implementação de uma estratégia de encaminhamento Inter-domínio com QoS (riQoS), desenvolvida sobre uma extensão BGP ao NS2 (ns-BGP). O riQoS estende os atributos do BGP e utiliza as mensagens UPDATE para divulgar informações de QoS entre os vários Routers Fronteira dos ASs. Para isso, o riQoS implementa alterações nos processos de comparação de rotas e de decisão do BGP tendo em conta a Largura de Banda e o Atraso em cada um dos Routers e ligações entre si. Em vez de utilizar métricas determinísticas, o BGP anuncia as informações através de métricas com significado estatístico: Available Bandwidth Index (ABI) e Delay Index (DelayI) [1], que permitem estimar os valores instantâneos da Largura de Banda disponível e do Atraso fim a fim

Design and implementation of a hierarchical SIP-based peer-to-peer network

Peer-to-peer (P2P) has gained popularity in Internet due to the increased number of users and distributed services such as file sharing and voice calls over IP (VoIP). Currently, the most popular P2P networks store information pertaining to its resources in a distributed manner using Distributed Hash Tables (DHT). In this type of networks, the peers are deterministically positioned and resources are also allocated to each peer for indexing in a deterministic manner. This paper presents a new hierarchical SIP based P2P network. A pure SIP solution was used because we believe that an open solution such as SIP can facilitate the creation of new types of services and permit the facilitated integration of different services. A two level hierarchy is used and is aimed towards the improvement of network efficiency where peers can move dynamically from one layer to another according to its available resources. In addition to this, the proposed implementation architecture allows the independence of the underlying DHT algorithms. The proposed architecture was implemented and tested in a realistic scenario which was created inside a Linux cluster. The DHT algorithms, Chord and EpiChord, were also implemented and used to index resources in either flat or hierarchical networks. Results indicate that the proposed two-layer hierarchy significantly improves the P2P overlay performance while in the presence of peers with limitations.(undefined

Solução aberta para uma rede de sondas de QoS na RCTS

A RCTS tem em operação, desde há vários anos, um conjunto de sondas do tipo appliance destinadas a aferir de forma contínua a qualidade da rede, tanto em IPv4 como IPv6. Normalmente, pelo facto de serem appliances, consequentemente “fechadas”, cria-se uma dependêndia de hardware e software. Apesar das appliances possuírem algumas características únicas ao nível de hardware, podem desenvolver-se soluções abertas (open source) equiparadas. Na realidade, vários sistemas de aferição de desempenho de redes, desenvolvidos em open source, tanto na GÉANT (rede académica europeia) como na Internet2 (rede académica americana), atingiram uma notoriedade que permite considerá-los como alternativas credíveis para as atuais sondas, se se provar a sua maturidade e estabilidade. Neste trabalho apresenta-se o desenvolvimento e teste de uma especificação de uma nova sonda para a RCTS, baseada em soluções open source.FEDER, através do Programa Operacional Fatores de Competitividade - COMPETE - e por Fundos Nacionais através da FCT - Fundação para a Ciência e Tecnologia, através do Projecto: FCOMP-01-0124-FEDER-02267

Design and evaluation of a multi-class based multicast routing protocol

Serie : Lecture notes in computer science, ISSN 0302-9743 ; vol. 5200Most of current multicast QoS routing proposals are based on the principle that QoS routes must be computed for each request, where requests explicitly express their resource requirements. As a result, within this environment, the goal of QoS routing is to satisfy individual request requirements, resorting to resource reservation to maintain those requirements after a feasible path has been found. This type of strategy is suited within the IntServ model but does not seem adequate in presence of DiffServ networks. According to DiffServ model, traffic flows are aggregated into specific classes-of-service and each flow receives a specific treatment accordingly to its class-of-service. There are no per flow guarantees, only per class differentiation. In this environment instead of per flow path computation, per class path calculation should be made, and so, within multicast scenarios, multiple multicast trees must be computed in order to satisfy different QoS requirements of different traffic classes. This paper presents a new multicast routing protocol enabling per class multicast tree computation. The proposed heuristics enable directed trees establishment, instead of reverse path ones, due to the importance of link asymmetry within an environment which is, essentially, unidirectional. The proposed protocol is implemented and simulated using Network Simulator. A set of simulation results are presented, analyzed and compared against PIM-SM, a widely deployed multicast routing protocol

Encaminhamento anycast em redes IPv6: uma proposta

O aparecimento do protocolo de comunicação IPv6 introduziu um novo paradigma de comunicação denominado anycast (um-para-um-de-muitos). Este novo paradigma, utiliza o conceito de grupo, à semelhança do que acontece com o multicast, mas em oposição a este, a informação é enviada apenas para um dos membros do grupo (tipicamente o mais próximo) e não para todos. Embora já se tenham passado alguns anos desde o seu aparecimento anycast tem sofrido uma lenta evolução,contribuindo para esta situação o facto de não existir ainda um protocolo normalizado, que permita `as aplicações usar de forma generalizada este paradigma de comunicação. Tradicionalmente as soluções para o problema de encaminhamento anycast são simplesmente baseadas no encaminhamento unicast sem alterações. No entanto, e tratando-se de um paradigma que usa o conceito de grupo,é de esperar que os protocolos de encaminhamento multicast, ou alguma variante destes, possam vir a constituir uma boa solução para a implementação do anycast ao nível da rede. O presente artigo apresenta um levantamento de propostas relacionadas com o tema e propõe um novo protocolo de encaminhamento anycast baseado no protocolo PIM-SM (Protocol Independent Multicast -Sparse Mode), denominado Tree-based Anycast Protocol (TAP). As alterações propostas ao protocolo PIM-SM são apresentadas na especificação do sistema, tendo sido o seu correto funcionamento aferido recorrendo ao Network Simulator 2 (ns-2.35)

Redes overlay peer-to-peer baseadas em SIP

As redes Peer-to-peer (P2P) tem vindo a ganhar popularidade na internet, devido ao aumento do número de utilizadores e de serviços de natureza distribuída, como a partilha de ficheiros, e as chamadas de voz sobre IP (VoIP). A criação deste tipo de redes, baseando-se em soluções abertas como o SIP, pode facilitar a criação de novos tipos de serviços, assim como permitir uma mais fácil integração de diferentes serviços. Neste trabalho foi desenvolvida uma implementação JAVA, capaz de criar redes P2PSIP com um ou dois níveis hierárquicos. A comunicação entre os nós da rede P2P, ´é feita através de um protocolo totalmente baseado em SIP. Como algoritmos a utilizar pelo overlay P2P, foram implementados o algoritmo Chord e EpiChord. Para comprovar o funcionamento da implementação JAVA, foram efectuados testes num ambiente real, recorrendo a uma topologia de rede emulada com o CORE

Infra-estrutura virtual nível 2 para interligação de máquinas virtuais em larga escala

O conceito de virtualização de redes encontra-se em expans. A capacidade de oferecer a uma infra-estrutura de rede a possibilidade de suportar várias redes virtuais distintas, sem as pressões impostas pelas redes de suporte,é um ponto de interesse tanto para operadoras como para académicos. Esta característica permite criar um ”mundo” virtual, auto-contido e com parâmetros controlados e alteráveis onde podem ser realizadas experiências com novas tecnologias ou mesmo, olhando sob um ponto de vista empresarial, oferecer serviços específicos a clientes, onde os parâmetros da rede são contratualizados com um revendedor. Este artigo descreve uma proposta de implementação de rede virtual, onde se aborda a descoberta de recursos e as diferentes metodologias para a troca de informacão entre os nós virtuais. As ligações criadas permitem virtualizar uma arquitectura níıvel 2 considerando cenários de conexão entre dois ou mais nós. São utilizadas várias abordagens de modo a criar a rede virtual, nomeadamente conexões baseadas em Sockets e RawSockets, assegurando uma comunicação controlada sobre uma infra-estrutura de rede operacional. Os parâmetros que estas ligações permitem oferecer foram avaliados numa situação real comprovando a possibilidade de disponibilização desta tecnologia sobre a infra-estrutura pública

Using machine learning on V2X communications data for VRU collision prediction

The datasets presented in this study are available in Zenodo at https://doi.org/10.5281/zenodo.7376770 (accessed on 16 December 2022), reference number [23]. These datasets are the raw data used for the testing and training of the ML algorithms in this work.Intelligent Transportation Systems (ITSs) are systems that aim to provide innovative services for road users in order to improve traffic efficiency, mobility and safety. This aspect of safety is of utmost importance for Vulnerable Road Users (VRUs), as these users are typically more exposed to dangerous situations, and their vehicles also possess poorer safety mechanisms when in comparison to regular vehicles on the road. Implementing automatic safety solutions for VRU vehicles is challenging since they have high agility and it can be difficult to anticipate their behavior. However, if equipped with communication capabilities, the generated Vehicle-to-Anything (V2X) data can be leveraged by Machine Learning (ML) mechanisms in order to implement such automatic systems. This work proposes a VRU (motorcyclist) collision prediction system, utilizing stacked unidirectional Long Short-Term Memorys (LSTMs) on top of communication data that is generated using the VEINS simulation framework (coupling the Simulation of Urban MObility (SUMO) and Network Simulator 3 (ns-3) tools). The proposed system performed well in two different scenarios: in Scenario A, it predicted 96% of the collisions, averaging 4.53 s for Average Prediction Time (s) (APT) and with a Correct Decision Percentage (CDP) of 41% and 78 False Positives (FPs); in Scenario B, it predicted 95% of the collisions, with a 4.44 s APT, while the CDP was 43% with 68 FPs. The results show the effectiveness of the approach: using ML methods on V2X data allowed the prediction of most of the simulated accidents. Nonetheless, the presence of a relatively high number of FPs does not allow for the usage of automatic safety features (e.g., emergency breaking in the passenger vehicles); thus, collision avoidance must be achieved manually by the drivers.This work has been supported by national funds through FCT—Fundação para a Ciência e Tecnologia within the Project Scope: UIDB/00319/2020

Efficiency of PRI and WRR DiffServ scheduling mechanisms for real-time services on UMTS environment

The next generation of mobile phones will be probably all-IP based enabling users to access Internet services. In order to make this possible a satisfactory quality of service, at least equal to the fixed Internet, must be ensured. To achieve this goal an end-to-end QoS system must be constructed. Another fact is the dominance of IP over other technologies due, in large measure, to its characteristic of working with heterogeneous technologies. Consequently, being IP the common denominator on a heterogeneous environment, it is important to develop end-to-end IP QoS guarantees for the different applications over distinct access technologies. This is particularly important for cellular wireless networks due to the ever growing expansion of mobile phone users. One way to contribute to this goal is to apply DiffServ QoS mechanisms to UMTS technology in order to model an End-to-End QoS communication system. A mapping of DiffServ CodePoints into UMTS classes can be applied in order to get efficient PHB configurations. This paper proposes an architecture to support end-to-end quality of service to several application services running on mobile UMTS user agents and communicating with servers located in a wired internet. The proposed architecture is based on a DiffServ model, where QoS parameters are set either by the user agent or by the SGSN. In particular, RED queue management and PRI or WRR scheduling policies are enforced. Different UMTS traffic classes are mapped into different DiffServ parameters. The performance of this architecture has been evaluated by simulation using NS, assuming different network load scenarios. In particular, the delay and packet loss experienced by VoIP, Video, FTP and HTTP traffic are evaluated in the cases of PRI and WRR scheduling policies, and compared to those measured when DiffServ is not implemented. Finally, a revenue function to estimate the profits that an ISP could expect by using a DiffServ implementation on IP UMTS core routers is proposed.(undefined