High data rate wireless packet data networks have made real-time IP based services available through mobile devices. At the same time, differences in the characteristics of radio technologies (802.11/WiFi and 3G networks) make seamless handoff across heterogeneous wireless networks difficult. Despite this, many believe that the ultimate goal of next generation networks (often referred to as the fourth generation) is to allow convergence of such dissimilar heterogeneous networks. Supporting voice over Internet Protocol in next-generation wireless systems is thought by some to require support for mobility and quality of service features. Currently a mobile node can experience interruptions or even sporadic disconnections of an on going real-time session due to handovers between both networks of different types and networks of the same type. Many tests have already been done in this area and one may wonder why it is worth spending even more time investigating it? This thesis focuses on the important problem of providing session security despite handovers between networks (be they operated by the same operator or different operators and be they the same link technologies or different). One of the goals in this thesis is to investigate how an ongoing speech session can continue despite a change in transmission media1. Additionally, a number of security threats that could occur due to the handover will be identified and presented. Finally, the most suitable solution to address these threats will be tested in a real environment. Eventual shortcomings and weaknesses will be identified and presented; along with suggestions for future work.  1 When utilizing IP over carriers such as wired Ethernet, WLAN, and 3G. / Trådlösa hög-hastighets datanät har möjliggjort appliceringen av realtids tjänster på mobil utrustning över IP. Samtidigt har skillnaderna i de olika radioteknologierna (802.11/WiFi och 3G näten) introducerat nya problem med att upprätthålla trådlösa kommunikationen tvärs den heterogena trådlösa accessen. Många tror att slutmålet för nästa generations nätverk (ofta refererade som fjärde generationens nätverk) är att tillåta konvergensen av dessa olika heterogena nätverk. Stödet för Voice over Internet Protokollet (VoIP) i nästa generations trådlösa nät tror somliga kräver ett inslag av kombination mellan mobilitet samt upprätthållandet av kvaliteten. För närvarande kan den mobila noden (MN) råka ut för störningar och även sporadiska avbrott av en pågående realtidssessionen på grund av övergångar mellan samma eller olika typer av medier. Många tester har redan gjorts inom det här området och man kan fråga sig varför det är värt att lägga ner ännu mer tid på att undersöka det här? Det här examensarbetet fokuserar på det viktiga problemet som handlar om att kunna erbjuda sessions säkerhet trots övergångar mellan näten (oavsett om dessa drivs av samma eller olika operatörer samt oavsett om de är av samma eller olika nätverks typ). Ett av målen för det här examensarbetet är att undersöka hur en pågående talsession behålls vid byte av transmissionsmedia2. Vidare kommer olika säkerhetsaspekter och hot som kan tänkas uppstå vid bytet att identifieras och presenteras. Slutligen kommer den mest lämpade lösningen till problemet att testas i verklig miljö. Eventuella brister och svagheter kommer att identifieras och redovisas i slutet av rapporten tillsammans med förslag på framtida arbete. 2 Då man nyttjar IP bärare som trådbundet Ethernet, WLAN och 3G.

In the current mobile network architecture, network traffic between user equipment (UE) and services deployed on the public cloud is tromboned towards the anchor point which could lead to network congestion. Deploying services closer to the UE, for example near the eNodeB, is a potential solution. The services are deployed on small scale data centers connected to, or collocated with the eNodeB, called ’eNodeB-Cloud’ (eNBC). Mobility of UEs presents a challenge for deploying services in an eNBC. When the UE is handed over from one eNodeB to another, seamless migration of UE context between the service instances running in different eNBCs needs to be ensured. In this thesis, we propose a Platform as a Service framework to enable UE context migration between eNBCs. The architecture consists of handover signaling mechanism, network session migration technology, context transfer protocol and a set of APIs towards the service. The evaluation of the prototype implementation shows that virtualization causes some extra delays to the UE context migration time. Whereas when virtualization is omitted, the time taken to migrate a UE context between two eNBCs is in the order of 12 ms on average, which is within the limit of handover interruption time between two LTE-eNodeBs.

Over the last two decades, mobile computing has gone from being a mere vision to becoming a reality, ubiquitously present in our everyday lives. There are different types of mobility, from user and terminal mobility, to mobility of services and sessions. This thesis is mainly about application mobility { the ability for an application to migrate between different host devices during its execution. The aim of this thesis work is to explore and advance the area of application mobility. The thesis approaches this goal through focusing on three research issues: Architectural considerations for application mobility; Context-awareness support and application adaptability; and Concept exploration.The contributions of this thesis include the identification of requirements for application mobility and a proposal for a decentralized, global scale architecture for application mobility, building on the peer-to-peer paradigm. Several prototypes of systems allowing application mobility are deployed, manifesting concepts such as decentralized system layout, context-awareness, context quality and global scope. Evaluations are both quantitative and qualitative. Other contributions of this thesis are the design and evaluation of a framework building on cloud and peer-to-peer technology to enable mobile sessions and an exploration of the concept of application mobility. / Sense Smart City, MOSA - mobil och öppen tjänste-access, NIMO - Nordic Interaction and Mobility Research Platform