With its enormous potential Voice over Internet Protocol is one of the latest buzzwords in information technology. Despite the numerous advantages of Voice over IP, it is a major technical challenge to achieve a similar call quality as experienced in the ordinary Public Switched Telephone Network. This thesis introduces standardized Internet protocols for Voice over IP, such as Session Initiation Protocol (SIP), Real-time Transport Protocol (RTP), in its background chapter. In order to provide better Quality of Service (QoS) Voice over IP applications should support a feedback mechanism, such as the Real-time Control Protocol (RTCP), and use accurate timing information, provided by the Network Time Protocol (NTP). Additionally this thesis considers synchronization issues in calls with two and more peers. After a rather academic overview of Voice over IP, the open source real-time application “minisip”, a SIP user agent, and its operation and structure for handling audio streams will be introduced. Minisip was extended by an implementation of NTP and RTCP to provide a test platform for this thesis. A clear conclusion is that the addition of global time helps facilitate synchronization of multiple streams from clients located any where in the network and in addition the ability to make one-way delay measurements helps SIP user agents to provide better quality audio to their users. / Röst över IP, eller Internettelefoni baserad på “Voice over Internet Protocol” (VoIP), har med sin stora potential blivit ett av de senaste modeorden inom informationsteknologin. Vid sedan av ett antal fördelar med VoIP så innebär det en stor teknisk utmaning att uppnå en likadan samtalskvalitet som i det vanliga, fasta, telenätet. I den här uppsatsen beskrivs hur tjänstevalitet för VoIP kan förbättras genom att noggrant tidssynkronisera de (två eller flera) klienter som deltar i ett telefonsamtal. För detta krävs dels en återkopplingsmekanism, såsom “Real-time Control Protocol” (RTCP), samt en gemensam tidsuppfattning i de inblandade klienterna, vilket kan uppnås med hjälp av “Network Time Protocol” (NTP). Dessa protokoll, liksom de övriga Internet-standarder som VoIP baseras på (såsom “Session Initiation Protocol” (SIP) och “Real-time Transport Protocol” (RTP), beskrivs inledningsvis i uppsatsen. För studien har en SIP-klient baserad på öppen källkod använts (“Minisip”), och utökats med NTP och RCTP funktionalitet för att testa den föreslagna förbättringen av VoIP. En tydlig slutsats är att kännedom om en “global tid” möjliggör synkronisering av multipla ljudströmmar från klienter som befinner sig på olika nätverk. Möjligheten att mäta paketfördröjningen (envägs) bidrar också till en förbättrad ljudkvalitet.

Exploiting context-aware environments, where sensors scattered in a environment update presence servers to indicate the environmental changes can be used to enable new services. Such systems have become feasible both in terms of technical di±culties and their cost. A current focus in this area of research is how a context-aware system should be designed so that it reduces both the cost and complexity of the infrastructure, but still provides the desired services. One of the key components of many context-aware systems is location sensing, because a user's location is one of the most used elements of information in context-aware services. In this paper, we address cost e®ective location services by utilizing measurements of WLAN signal strength. We derive from these measurements an estimate of a device's location, and make this location information available via a SIP Presence User Agent, thus making location information readily available to services that might wish to use this information - while hiding details of how this information is acquired from these services. / Genom att utnyttja kontextmedvetna miljöer, där sensorer i en miljö uppdaterar närvarande servrar med information omändringar i omgivningen, så kan man öppna upp vägar för nya tjänster. Sådana system har blivit utförbara bade när det gäller tekniska svarigheter och deras kostnader. Inom forskning som rör sådana här system ägnas mycket uppmärksamhetåt hur en kontextmedveten miljö borde designas för att minimera både kostnaden och komplexiteten av infrastrukturen, men fortfarande tillhandahålla den önskade tjänsten. En av huvudkomponenterna i många kontextmedvetna system är platsuppfattning, eftersom en användares position är en av de mest använda elementen av information i kontextmedvetna tjänster. I den här uppsatsen ägnar vi oss åt kostnadseffektiva platstjänster genom att mäta signalstyrkan av ett WLAN. Genom dessa mätningar uppskattar vi en enhets position och gör denna information tillgänglig via en SIP Presence User Agent, och gör på så vis platsinformationen tillgänglig för tjänster som kan vilja ha den { utan att avslöja detaljer om hur informationen har skaffats.

This Master thesis work was carried out at theWireless Center at KTH and it is part of a pilot project. This thesis is conducted for the Institute for Microelectronics and Information Technology (IMIT) at the Royal Institute of Technology (KTH) in Stockholm (Sweden) and for the Department of Telecommunications at Politecnico di Torino in Turin (Italy). This thesis addresses an area with significant potential for offering services to mobile users. In such a scenario users should have minimal interaction with applications which, by taking into account available context information, should be able to make decisions, such as setting up delivery paths between peers without requiring a third party for the negotiation. In wireless reconfigurable networks, the mobile users are on the move and must deal with dynamic changes of network resources. In such a network, mobile users should be able to contact other peers or resources by using the current route. Thus although manual configuration of the network is a possible solution, it is not easily used because of the dynamic properties of the system which would demand too much user interaction. However, existing discovery protocols fall short of accomodating the complexity of reconfigurable and heterogeneous networks. The primary objective of this thesis work was to investigate a new approach at the application level for signaling by taking advantage of SIP’s features. The Session Initiation Protocol (SIP) is used to provide naming and localization of the user, and to provide functionality to invite users to establish sessions and to agree on communication parameters. The Specific Event Notification of the SIP protocol provides a framework for the notification of specific events and I believed that it could be instantiated as solution to the problem for reconfigurable application networks. This thesis proposes a method for providing localization information to SIP User Agents in order to establish sessions for service discovery. Furthermore, this method should consider context meta-data to design strategies effective in heterogeneous networks. A viable solution must support (re)location of users at the application layer when they roam between different wireless networks, such as GPRS and WLAN. An analysis of the implications of the proposed model is presented; in this analysis emphasis has been placed on how this model interacts with existing services.

This Master’s Thesis concerns the technical problems and solutions in the Telia Mobile’s Golden Gate Architecture. The Golden Gate project will bridge service control from the IPnetwork to the circuit switched network. Connecting the different users of PSTN, GSM, W-LAN, and GPRS networks together will require solutions to many problems. Most of the problems have already been defined by Telia. Our task is to evaluate two parts of the Golden Gate architecture, namely the Interconnect- and Service Provider roles. The Interconnector provider connects networks of different technical standards and enables other network operators to reach Service Providers on the Internet or other IP-based networks. The role concerns mainly mapping between SS7 signaling and the Session Initiation Protocol (SIP), charging and billing. Via the Interconnector the Service Provider can connect different services to any network. We will describe the SIP-protocol in detail and then we will look into the mapping between SS7 and SIP. We will also propose a charging model. It is important to have a solution that supports roaming between the different networks, we will evaluate such a solution. Most of the protocols (INAP, ENUM, MAP and ISUP) that are involved in the Golden Gate architecture are not completely defined. There are many Internet Drafts that discuss the possible functionality of the protocols and the interworking between them. Many different Internet-workgroups are working with these issues. No one seems to have the right answers for the interconnection between the protocols involved. Since the IP-telephony will probably replace today’s telephony systems, it is important to ensure a suitable Quality of Service (QoS), security that guarantees privacy, and a fair billing function. These are the three major problems in the IP-telephony world. IP-Telephony or Voice over IP (VoIP) has been on the market for a long time, there are many 'free IP-call sites' that use VoIP, but the quality of the calls are not yet good enough to replace traditional telephony. Our task here is to make sure that the necessary quality of service is provided, and a reliable charging model is used.

Market research reports by In-Stat, Gartner, and the Swedish Post and Telecom Agency (PTS) reveal a growing worldwide demand for Voice over IP (VoIP) and smartphones. This trend is expected to continue over the coming years and there is wide scope for mobile VoIP solutions. Nevertheless, with this growth in VoIP adoption come challenges related with quality of service and security. Most consumer VoIP solution, even in PCs, analog telephony adapters, and home gateways, do not yet support media encryption and other forms of security. VoIP applications based on mobile platforms are even further behind in adopting media security due to a (mis-)perception of more limited resources. This thesis explores the alternatives and feasibility of achieving VoIP security for mobile devices in the realm of the IP Multimedia Subsystem (IMS).

Traffic for real-time entertainment applications has increased over the past years and now holds one of the largest portions of the traffic on the Internet. This trend has been spotted by Ida Infront who wishes to integrate and support a streaming protocol in their Enterprise Service Bus (ESB). This thesis first surveys three streaming protocols and techniques (SIP, RTSP and HTTP-base streaming) in terms of general usage areas and suitability for integration with the company ESB. Second, this thesis investigates how these protocols can be implemented using a proxy-based design together with the ESB. After describing one design alternative for each protocol, the thesis finally presents a proof-of-concept implementation of an RTSP proxy. The proxy is implemented and tested for performance and added packet jitters under different loads. The main contribution of the thesis is a reverse RTSP proxy application that integrates with the ESB and offers both routing and logging functionalities. In tests where we put the proxy under load we see that the CPU and memory usage is low and that the bottleneck appears to be the network bandwidth. But we also see a small added jitter that potentially could scale and must be taken into account when using such a proxy application.

Les réseaux mobiles ont un modèle en couches, avec: (1) un réseau d’accès IP offrant une connectivité IP aux utilisateurs; (2) une couche de contrôle de service, l’IMS; (3) une couche d’interaction pour le contrôle des politiques réseau, le PCC. Ce modèle, centralisé et hiérarchique, serait à l’origine de problèmes de passage à l’échelle et de qualité de service en cas d’explosion du volume de trafic de données à transporter. Dans cette thèse, un nouveau modèle pour les réseaux mobiles du futur est proposé: Ultra Flat Architecture (UFA). UFA utilise l’IMS pour le contrôle de tout type d’applications. UFA est dite plate car elle réduit le nombre de types de nœuds réseau à 2 principalement: (1) une Gateway UFA regroupant à la fois l’ensemble des fonctionnalités du réseau d’accès IP, de l’IMS et du PCC; (2) le terminal. Après la conception de l’architecture, nous avons spécifié et évalué trois procédures réseau principales pour UFA : l’enregistrement/authentification, l’établissement de service et la mobilité. Nous avons optimisé les deux premières procédures par rapport aux procédures standardisées de l’IMS. Par exemple, la procédure d’établissement de service présente un délai réduit et permet une configuration du service ou de la couche de transport selon les ressources disponibles dans le réseau. Nous avons développé une procédure de mobilité pour UFA, se basant sur le transfert, d’une Gateway UFA à une autre, des contextes de toutes les couches OSI liés au terminal, et sur la détermination proactive par la Gateway UFA des paramètres de toutes les couches du terminal. Tous les résultats obtenus montrent le grand intérêt d’UFA et des architectures plates plus généralement. / Mobile networks have a layered model, with: (1) an IP access network providing IP connectivity to users, (2) a service control layer, IMS, (3) an interaction layer for policy control, PCC. This model, centralized and hierarchical, will cause scalability and QoS problems in case of data volume explosion. In this thesis, a new model for future mobile networks is proposed: Ultra Flat Architecture (UFA). UFA uses IMS to control all application types. UFA is flat since it reduces the number of network node types to 2 mainly: (1) a UFA Gateway that includes the functions of the IP access network, the IMS and the PCC, and (2) a terminal. After designing the architecture, we specified and evaluated three main procedures for UFA: registration / authentication, service establishment and mobility. We have optimized the first two procedures compared to standard procedures of the IMS. For example, the service establishment procedure has a reduced delay and allows the configuration of the service or the transport layer according to the resources available in the network. We have developed a mobility procedure for UFA. It is based on the transfer, from one UFA Gateway to another, of the all OSI-layers contexts related to that terminal, and on a proactive determination of the all OSI-layers parameters, necessary for the terminal attachment to the new UFA Gateway. All obtained results show the great interest of UFA and of flat architectures more generally.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第17902号 / 農博第2025号 / 新制||農||1017(附属図書館) / 学位論文||H25||N4798(農学部図書室) / 30722 / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 德地 直子, 教授 吉岡 崇仁, 准教授 長谷川 尚史 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

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Denna studie utforskar klimatpåverkan och kostnadseffektivitet av två byggtekniker för ett tänkt småhus i Uppsala. Studien gör en jämförelse mellan prefabricerade strukturella isolerande paneler (SIP) med expanderad polystyrenisolering (EPS) gentemot en träregelkonstruktion med mineralullsisolering. Syftet är att jämföra deras miljöpåverkan och ekonomiska aspekter genom livscykelanalys (LCA) och livscykelkostnadsanalys (LCC) specifikt för byggnader. Studien är strikt inriktad på byggskedet A1-A5, vilket inkluderar både produktsskedet A1-A3 och byggproduktionsskedet A4-A5. Med A1-A3 avses framställningen av byggmaterial, medan A4-A5 innefattar användningen av dessa material i byggprocessen. Studien även granskar specifika materialval och standardtjocklekar för SIP med EPS och ifall dessa tjocklekar stämmer med allmänna standarder för byggnadsverk. Denna utnyttjar användningen av moderna mjukvaror för att förenkla beräkningarna av LCA och LCC inom byggbranschen. Vi valde att använda programvaran One Click LCA. Programmet används för att genomföra hållbarhetsanalyser, hållbarhetsanalyser skiljer sig från LCA genom sitt bredare fokus på hållbarhetsaspekter, inklusive sociala och ekonomiska dimensioner, utöver de rent miljömässiga faktorer som LCA fokuserar på. Programvaran baseras på en omfattande databas av byggnadsmaterial och deras miljövarudeklarationer (EPD), vilket underlättar beräkningen av en byggnads totala miljöpåverkan.   Studien indikerar att konstruktionen med träregelkonstruktionen producerar ett lägre koldioxidutsläpp i jämförelse med konstruktioner byggd av SIP med EPS. De ökade utsläppen för SIP-konstruktionen är huvudsakligen ett resultat av transportavståndet och de betydande koldioxidekvivalenterna under produktionsstadiet. När det gäller koldioxidutsläpp visar data att SIP-konstruktionen har en större miljöpåverkan, med 238 kg CO2e/m2 Atemp (uppvärmda arean av huset), jämfört med träregelkonstruktionen som genererar 162 kg CO2e/m2 Atemp.   Ekonomiskt är SIP-konstruktionen i studien mer kostsam än träregelkonstruktionen. Det finns en kostnadsökning på 22,3% för SIP-konstruktionen jämfört med träregelkonstruktionen. Kostnaden för SIP-konstruktionen uppgår till 6022 kr/m2 Atemp, medan träregelkonstruktionen kostar 4678 kr/m2 Atemp. Denna ökning kan främst hänföras till högre material- och transportkostnader för SIP-elementen. Studien betonar vikten av att balansera ekonomiska och miljömässiga faktorer vid val av byggteknik och den framhäver potentialen att fortsätta utforska och förbättra byggnadsmaterial och byggprocesser för att göra byggsektorn mer hållbar, vilket inbegriper att minska klimatpåverkan från material som EPS-isolering och OSB-skivor (som är en skiva tillverkad av sammanpressade träspån och lim), samt utforska alternativa material såsom polyuretan (PU foam). / This study explores the climate impact and cost effectiveness of two building techniques for a single-family house in Uppsala: Structural Insulated Panels (SIP) with EPS insulation compared with a timber frame with mineral wool insulation. The purpose is to assess their environmental impact and economic aspects through life cycle analysis (LCA) and life cycle cost analysis (LCC). The study encompasses the stages of LCA and LCC named as the production stage and the construction production stage for these techniques. The 'production stage' refers to the manufacturing of building materials, while the 'construction phase' involves using these materials in the building process.  This study takes advantage of modern analysis software to ease the process of performing LCA and LCC analyses. We have decided to use the software One Click LCA to simplify the LCA process and perform sustainability analyses. A sustainability analysis differs from LCA by its broader focus on sustainability aspects, including social and economic dimensions, in addition to the purely environmental factors that LCA focuses on. The software is based on an extensive database of building materials and their environmental product declarations (EPD), which facilitates calculating a building's total environmental impact. The study indicates that constructions with timber frames produce lower carbon dioxide emissions compared to those using SIP constructions.  In terms of carbon dioxide emissions, the data show that SIP construction has a greater environmental impact, with 238 kg CO2e/m2 Atemp, compared to timber frame construction, which generates 162 kg CO2e/m2 Atemp. Economically, SIP construction is more costly than timber frame. There is a cost increase of 22.3% for the SIP construction compared to the timber frame construction. The cost of the SIP construction amounts to 6022 SEK/m2 Atemp, while the timber frame construction costs 4678 SEK/m2 Atemp. This increase is mainly attributable to higher material and transport costs for the SIP construction. The study emphasizes the importance of balancing economic and environmental factors in the choice of building technology. It also highlights the potential to continue exploring and improving building materials and construction processes to make the construction sector more sustainable, including reducing the climate impact from materials like EPS insulation and OSB boards, and exploring alternative materials such as polyurethane (PU foam).