Jochen Eisl

Co-operative handover in 3G System Architecture Evolution

This paper outlines the challenges and possible solutions for mobility management between 3GPP and non-3GPP access systems. Given the differences between technologies and mobility principles in 3GPP and non-3GPP access networks it is feasible to implement the mobility features between 3GPP and non-3GPP networks in a stepwise approach. This allows on one hand an early market entry of a basic solution and on the other hand a later enhancement aiming at co-operative handover decisions and context aware mobility. The latter enables a mobile node to change point of network attachment in a secure and seamless fashion. In order to enable short term deployment of mobility over heterogeneous access networks, mobile IPv4 and mobile IPv6 should be introduced with some additional changes for the handover of non-real-time traffic and non-co-operative handover. In a further step, an enhanced mobility solution shall be introduced which supports a preparation phase including possible pre-authentication before the handover of the transmission path. In conjunction with this approach it is proposed to enable coordination on handover decision between the mobile node and the evolved packet core network.This contribution presents a graph based approach for modelling the effects of both attacks against computer networks and response measures as reactions against the attacks. Certain properties of the model graphs are utilized to quantify different response metrics which are well-kown from the pragmatic view of network security officers. Using these metrics, it is possible to (1) quantify practically relevant properties of a response measure after its application, and (2) estimate these properties for all available response measures prior to their application. The latter case is the basis for the selection of an appropriate reaction to a given attack. Our graph-based model is similar to those used in software reliability analysis and was designed for a scalable granularity in representing properties of the network and its components to be protected. Different examples show the applicability of the model and the resulting metric values.

Towards sustained multi media experience in the Future Mobile Internet

High quality and sustained multi media experience is expected to be a major feature of the Future Mobile Internet (FMI). Currently deployed novel mobile network technologies such as LTE (Long Term Evolution) make use of the Internet and its best-effort TCP/IP protocol stack to enable applications. The orientation towards TCP/IP is logical due to the success of the Internet. However, TCP/IP still provides almost no support for Quality of Service (QoS). Hence, it seams to be a contradiction that high quality services can be reached by TCP/IP. In this contribution, we discuss recent advances for sustained high quality multi media experience in FMI. Therefore, we first cast some new lights on the achievement in video streaming. We review the LTE and EPS (Evolved Packet System) architecture of the anticipated FMI, and discuss particularly the concept of bearers, which is also used an abstraction for QoS support. Subsequently, we introduce new network concepts which might contribute to improved QoS and performance management in the FMI such as flow-based QoS enforcement in routers, Network Virtualization, and Network Federation. Based on this analysis, we develop an initial service for supporting improved flow management for video streaming service in the FMI. Finally, we outline how flow management can improve the quality of videos, but outline also what happens if inappropriate flow switching mechanisms are applied.

Interconnected content distribution in LTE networks

Consumption of multimedia content via the Internet by home users is on the rise. In addition to the delivery via traditional media like TV, many live events are streamed via the Internet. The increased availability of smart-phones, netbooks and high wireless access bandwidth encourages users to consume content on-the-go via mobile technologies. This work identifies requirements necessary to perform internetwork content distribution, proposes a general architecture which fulfills these requirements and gives and discusses an exemplary instantiation of the architecture for Long Term Evolution (LTE) networks. Major focus will be given in this paper in the mapping of a general architecture for interconnected and federated CDNs to the expected and available interfaces in LTE architectures.

Analysis of Managed and Over-the-Top Streaming Services in Mobile Networks

Optimizing multimedia streaming in 3GPP mobile broadband networks (e.g. HSPA, LTE) in terms of user experience and network resource utilization is one of the most important topics for mobile network operators. The primary reason is that streaming services consume more than half of the total bandwidth. Before designing new concepts and solutions it is fundamental to understand in detail the performance and behavior of multimedia applications for the mobile access. For this reason we have carried out several field experiments to obtain knowledge about typical bandwidth consumption, ability to adapt video bit-rate to changed network conditions, protocol and other service specific issues for the most popular over-the-top and managed video services. We have detected that observed data rates apart from the video encoding and the specific content also depend on client and server implementations. Surprisingly, support for rate adaptation in current implementations of managed and over-the-top streaming services is not very common, in some cases with limited feature set. From the obtained results we conclude that measurements need to continue with a shift from field experiments to lab environment in order to obtain further knowledge of streaming characteristics, which could not be revealed in the current measurements.