Morten Schläger

A Distributed IP Mobility Approach for 3G SAE

Future generations of mobile operator networks, based on an all-IP-based flat architecture and a multitude of different access technologies, require a proper IP-based mobility management in place. In this article, a scalable and completely distributed mobility management is presented which is based on a Distributed Hash Table data structure. The Distributed IP Mobility Approach (DIMA) remains completely compatible towards Mobile IP and its variants Hierarchical Mobile IP and Proxy Mobile IP. We examine the average service time per packet and the load caused by lookups in the system, by applying a suitable mobility model and by using a traffic model consisting of a mix of representative traffic classes (HTTP, VoIP, Audio and Video streaming). Thereby, we show that the system remains scalable allowing to serve an arbitrary amount of participants, provides a network-based route optimization and a better resilience than Mobile IP at the cost of only slightly increased signalling effort.

Charging in the IP Multimedia Subsystem: A Tutorial

The IP multimedia subsystem enables a service-rich communication landscape and the convergence of mobile and fixed networks. However, IMS solutions can succeed only when charging for these new services is supported in a flexible and efficient manner. To meet the new challenges, the 3GPP recently introduced a generic charging framework. In this article we give a short overview of the 3GPP charging framework and then describe how IMS charging works with in this framework. To illustrate IMS charging, we discuss an IMS scenario in which three persons with different payment methods conduct a teleconference.

A Mechanism for Charging System Self-Configuration in Next Generation Mobile Networks

Self-management is an emerging idea in charging system research taken over from autonomic computing to address the complexity problem of system deployment, maintenance and administration and to improve the performance and flexibility of the charging system what will as a whole eventually decrease its total cost of ownership. In this paper, we describe a mechanism for charging system self-configuration when new network or service elements that record charging information are added as well as for charging system self-optimisation during every-day operation.

Data collection in future mobile networks

Future mobile networks will be increasingly heterogeneous. Already today, wireless LAN is used by many mobile network operators as an addition to traditional technologies like GSM and UMTS; WiMax and 3GPP Long Term Evolution (LTE) will be added. Having heterogeneous wireless networks, one challenging research question needs to be answered: Which user should be served by which access network and when to conduct a handover? For such decisions, information on the state of networks and terminals is required. In this publication, we simulate mobile networks in which a central entity called Network Resource Management (N-RM) gives handover recommendations to mobile terminals. Based on these recommendations and local knowledge on link qualities, the terminals choose the cell to switch to. The N-RM should have a global view on the networks to give best recommendations. We designed the Generic Metering Infrastructure (GMI), a publish/subscribe system to collect information about access networks and terminals efficiently.We investigate the tradeoff between the signalling overhead caused by data collection and the quality of the handover decisions and show, how smart monitoring can reduce the amount of measurement data while ensuring the efficient use of heterogeneous networks. In addition, our simulation results show that combined local and central handover decisions significantly increase the capacity of the networks as compared to only local decisions.

A metering infrastructure for heterogenous mobile networks

The next generation of mobile access networks will support different access technologies like UMTS, WLAN, WiMax and LTE. Optimal handover decisions between different access networks have to take various types of information into account, such as the load of possible target cells. However, collecting this information and transporting it to mobility management decision engines is costly in terms of bandwidth. With our flexible Generic Metering Infrastructure (GMI) we are able to collect state information from the core and access networks efficiently. Using the GMI, network operators will be able to control handover decisions for their users.

Data Collection for Heterogeneous Handover Decisions in beyond 3G Networks

Future mobile networks will be increasingly heterogeneous. Already today, wireless LAN is used by many mobile network operators as an addition to traditional technologies like GSM and UMTS; WiMax and 3GPP Long Term Evolution (LTE) will be added. Having heterogeneous wireless networks, one challenging research question needs to be answered: Which user should be served by which access network at which time and when to conduct a handover? For such decisions, information on the state of networks and terminals is required.