14 research outputs found

    Cost Analysis of the IMS Presence Service

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    IMS (IP Multimedia Subsystem) is the technology that will merge the Internet (packet switching) with the cellular world (circuit switching). Presence is one of the basic services which is likely to become omnipresent in IMS (IP Multimedia Subsystem). It is the service that allows a user to be informed about the reachability, availability, and willingness of communication of another user. The flow of messages will be massive for large amount of publishers and watchers joining an IMS system, because of the security architecture of the IMS. Although the IETF engineers have proposed several solutions to reduce the signalling overhead to facilitate the presence service, the heavy traffic flows have been compromised with several factors like real time view and information segregation etc. In this paper, we propose a mathematical model to analyse the system-performance of the IMS presence service during heavy traffic. The model derives the cost functions that are based on the real parameters of the Presence server. Simulation results have been shown that provide useful insight into the system behaviour

    Contributions to presence-based systems for deploying ubiquitous communication services

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    Next-Generation Networks (NGNs) will converge the existing fixed and wireless networks. These networks rely on the IMS (IP Multimedia Subsystem), introduced by the 3GPP. The presence service came into being in instant messaging applications. A user¿s presence information consists in any context that is necessary for applications to handle and adapt the user's communications. The presence service is crucial in the IMS to deploy ubiquitous services. SIMPLE is the standard protocol for handling presence and instant messages. This protocol disseminates users' presence information through subscriptions, notifications and publications. SIMPLE generates much signaling traffic for constantly disseminating presence information and maintaining subscriptions, which may overload network servers. This issue is even more harmful to the IMS due to its centralized servers. A key factor in the success of NGNs is to provide users with always-on services that are seamlessly part of their daily life. Personalizing these services according to the users' needs is necessary for the success of these services. To this end, presence information is considered as a crucial tool for user-based personalization. This thesis can be briefly summarized through the following contributions: We propose filtering and controlling the rate of presence publications so as to reduce the information sent over access links. We probabilistically model presence information through Markov chains, and analyzed the efficiency of controlling the rate of publications that are modeled by a particular Markov chain. The reported results show that this technique certainly reduces presence overload. We mathematically study the amount of presence traffic exchanged between domains, and analyze the efficiency of several strategies for reducing this traffic. We propose an strategy, which we call Common Subscribe (CS), for reducing the presence traffic exchanged between federated domains. We compare this strategy traffic with that generated by other optimizations. The reported results show that CS is the most efficient at reducing presence traffic. We analyze the load in the number of messages that several inter-domain traffic optimizations cause to the IMS centralized servers. Our proposed strategy, CS, combined with an RLS (i.e., a SIMPLE optimization) is the only optimization that reduces the IMS load; the others increase this load. We estimate the efficiency of the RLS, thereby concluding that the RLS is not efficient under certain circumstances, and hence this optimization is discouraged. We propose a queuing system for optimizing presence traffic on both the network core and access link, which is capable to adapt the publication and notification rate based on some quality conditions (e.g, maximum delay). We probabilistically model this system, and validate it in different scenarios. We propose, and implement a prototype of, a fully-distributed platform for handling user presence information. This approach allows integrating Internet Services, such as HTTP or VoIP, and optimizing these services in an easy, user-personalized way. We have developed SECE (Sense Everything, Control Everything), a platform for users to create rules that handle their communications and Internet Services proactively. SECE interacts with multiple third-party services for obtaining as much user context as possible. We have developed a natural-English-like formal language for SECE rules. We have enhanced SECE for discovering web services automatically through the Web Ontology Language (OWL). SECE allows composing web services automatically based on real-world events, which is a significant contribution to the Semantic Web. The research presented in this thesis has been published through 3 book chapters, 4 international journals (3 of them are indexed in JCR), 10 international conference papers, 1 demonstration at an international conference, and 1 national conferenceNext-Generation Networks (NGNs) son las redes de próxima generación que soportaran la convergencia de redes de telecomunicación inalámbricas y fijas. La base de NGNs es el IMS (IP Multimedia Subsystem), introducido por el 3GPP. El servicio de presencia nació de aplicaciones de mesajería instantánea. La información de presencia de un usuario consiste en cualquier tipo de información que es de utilidad para manejar las comunicaciones con el usuario. El servicio de presencia es una parte esencial del IMS para el despliegue de servicios ubicuos. SIMPLE es el protocolo estándar para manejar presencia y mensajes instantáneos en el IMS. Este protocolo distribuye la información de presencia de los usuarios a través de suscripciones, notificaciones y publicaciones. SIMPLE genera mucho tráfico por la diseminación constante de información de presencia y el mantenimiento de las suscripciones, lo cual puede saturar los servidores de red. Este problema es todavía más perjudicial en el IMS, debido al carácter centralizado de sus servidores. Un factor clave en el éxito de NGNs es proporcionar a los usuarios servicios ubicuos que esten integrados en su vida diaria y asi interactúen con los usuarios constantemente. La personalización de estos servicios basado en los usuarios es imprescindible para el éxito de los mismos. Para este fin, la información de presencia es considerada como una herramienta base. La tesis realizada se puede resumir brevemente en los siguientes contribuciones: Proponemos filtrar y controlar el ratio de las publicaciones de presencia para reducir la cantidad de información enviada en la red de acceso. Modelamos la información de presencia probabilísticamente mediante cadenas de Markov, y analizamos la eficiencia de controlar el ratio de publicaciones con una cadena de Markov. Los resultados muestran que este mecanismo puede efectivamente reducir el tráfico de presencia. Estudiamos matemáticamente la cantidad de tráfico de presencia generada entre dominios y analizamos el rendimiento de tres estrategias para reducir este tráfico. Proponemos una estrategia, la cual llamamos Common Subscribe (CS), para reducir el tráfico de presencia entre dominios federados. Comparamos el tráfico generado por CS frente a otras estrategias de optimización. Los resultados de este análisis muestran que CS es la estrategia más efectiva. Analizamos la carga en numero de mensajes introducida por diferentes optimizaciones de tráfico de presencia en los servidores centralizados del IMS. Nuestra propuesta, CS, combinada con un RLS (i.e, una optimización de SIMPLE), es la unica optimización que reduce la carga en el IMS. Estimamos la eficiencia del RLS, deduciendo que un RLS no es eficiente en ciertas circunstancias, en las que es preferible no usar esta optimización. Proponemos un sistema de colas para optimizar el tráfico de presencia tanto en el núcleo de red como en la red de acceso, y que puede adaptar el ratio de publicación y notificación en base a varios parametros de calidad (e.g., maximo retraso). Modelamos y analizamos este sistema de colas probabilísticamente en diferentes escenarios. Proponemos una arquitectura totalmente distribuida para manejar las información de presencia del usuario, de la cual hemos implementado un prototipo. Esta propuesta permite la integracion sencilla y personalizada al usuario de servicios de Internet, como HTTP o VoIP, asi como la optimizacón de estos servicios. Hemos desarrollado SECE (Sense Everything, Control Everything), una plataforma donde los usuarios pueden crear reglas para manejar todas sus comunicaciones y servicios de Internet de forma proactiva. SECE interactúa con una multitud de servicios para conseguir todo el contexto possible del usuario. Hemos desarollado un lenguaje formal que parace como Ingles natural para que los usuarios puedan crear sus reglas. Hemos mejorado SECE para descubrir servicios web automaticamente a través del lenguaje OWL (Web Ontology Language)

    Presence-based integration of wireless sensor network and IP multimedia subsystem : architecture implementation and case studies

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    Services are the main driving forces of the Telecommunication industry. In old days the traditional networks e.g. PSTN and mobile cellular networks provide basic services to customers such as voice call, SMS. Unlike mobile cellular networks, Internet provides wide variety of services that allow users to communicate in different ways for example E-mail, WWW, VoIP, and Instant Messaging. To benefit from these Internet (IP) based services and to support new value-added services in mobile cellular networks, the IP Multimedia Subsystem (IMS) is defined. It aims at convergence of Internet and the cellular world. IMS introduced an architectural framework envisioned by telecom experts for providing wide variety of multimedia services for example Presence, Context-based applications, Conferencing, Video-on-Demand, Instant Messaging to name just a few. The main ingredients of these services are data which can be either provided by users or derived from external sources (other networks). In recent years, Wireless Sensor Networks have emerged as networks of tiny devices, sensor nodes. WSNs are characteristically different from existing networks. In general, a WSN is a data oriented network in which sensors sense physical environment and produce data to deliver it to interested applications. These applications are usually external to WSN and reside in an external network (e.g. IMS). The applications or services use this physical data to deliver enhanced services such as context-based services to mobile users. The challenge is to integrate WSN with IMS so that the WSN data can be accessible to IMS services or applications. This thesis exploits a presence-based approach for the integration of WSN and IMS network. A standard interface for data exchange between WSN and IMS has been devised in the Telecommunication Service Engineering group. The data exchange between WSN and IMS services/applications is realized as a publish-subscribe mechanism. In publish-subscribe mechanism the applications subscribe to WSN services (data) and get notified when sensors report any data while the WSN is acting as publisher to publish sensor data to IMS. The presence-based WSN -- IMS architecture provides an abstraction to services and applications for accessing variety of sensed data from different WSNs. The presence based WSN-IMS architecture realizes two main architectural entities, the integrated WSN-IMS gateway and an IMS extended presence server. These two architectural entities play a key role in interworking of WSN and IMS network. The overall architecture has been implemented and tested with prototype applications as well as a performance evaluation has been done to see the efficiency and applicability of the integrated architectur

    Towards consolidated presence

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    hauswirth2010aInternational audiencePresence management, i.e., the ability to automatically identify the status and availability of communication partners, is becoming an invaluable tool for collaboration in enterprise contexts. In this paper, we argue for efficient presence management by means of a holistic view of both physical context and virtual presence in online communication channels. We sketch the components for enabling presence as a service integrating both online information as well as physical sensors, discussing benefits, possible applications on top, and challenges of establishing such a service

    A Microservice based Architecture for a Presence Service in the Cloud

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    Presence service enables sharing of, and a subscription to the end users presence (online or offline) status. Primarily used for instant messaging applications, the presence service now finds its way into innovative solutions for domains such as wireless sensor networks and Internet of Things. The growth in users of instant messaging applications is ever increasing since the advent of social media networks. Presence service needs to be highly scalable to handle growing load of the users. Moreover, the user activity is inherently dynamic in nature which requires the presence service to be highly elastic to utilise resources efficiently. Traditional presence services are built as monoliths. Monolithic architectures by design are difficult to scale, lacks elasticity and are resource inefficient. Moreover, overprovisioning of resources to handle unanticipated loads further adds to resource inefficiency. Cloud computing and microservices are emerging paradigms that can help tackling the challenges above. Cloud computing with three key facets: Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS), and Software-as-a-Service (SaaS) enable rapid provisioning and release of resources (e.g. storage, compute, network) on demand. Microservices is an approach of developing applications as a set of smaller, independent, and individually scalable services which communicate with each other using lightweight protocols. The on-demand nature of cloud computing provides a platform to achieve elastic scalability whereas microservices increase the scalability of the architecture. This thesis presents a microservice architecture for a presence service in the cloud. The architecture is based on a state of the art business model. The proposed architecture has three main components: A stateless front-end, a repository and a cache. The front end is built as a set of microservices exposed as SaaS. The front end, to remain technology agnostic, communicates with the repository using the Representational State Transfer (REST) interface. The cache provides fast data access to the front end. The front end microservices use message queues to communicate with each other. Besides, to check the feasibility of the architecture, a proof of concept prototype is implemented for a Session Initiation Protocol for Instant Messaging and Presence (SIMPLE) based presence service. Performance measurements have been made for the proposed and traditional architectures. Also, a comparative analysis of the results is done. The analysis of the results shows that the proposed architecture provides the desired scalability and elasticity to the presence service. Moreover, the proposed architecture provides lower response time and higher throughput in comparison to the traditional architecture
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