Matthias Siebert

Policy based networking in the integration effort of 4G networks and services

We present system integration requirements and provide a new framework to support the integration of 4G networks and services. This framework uses a policy based networking concept in order to provide the unified control in the oncoming 4G networks and services. We also provide an analysis of the candidate signaling protocols in this framework. Two approaches are described: i) the unified QoS, mobility, and security signaling and ii) the heterogeneous QoS, mobility, and security signaling. In addition, we introduce user, terminal, network and service profiles and management in order to provide a user centric approach and consider different user, terminal, network, and service constraints in order to better adapt the user service as well as the network configuration to these constraints. Finally, we give a short estimation on the composition of exchanged signaling data with respect to the aspired level of integration.

Enhanced measurement procedures for vertical handover in heterogeneous wireless systems

This paper presents an approach to realize integration of heterogeneous systems. Vertical handover thereby is seen as a key feature to allow for interoperability. In order to properly perform handover decisions, interference information with respect to the target system need to be available. For this, dedicated scanning procedures are necessary causing problems if a mobile is using continuous transmission and reception schemes like in UMTS FDD mode. To overcome this problem, different methods are mentioned, whereby a special focus is put on the compressed mode, since alternative means of making measurements are not yet considered within 3GPP. However, it is shown by means of simulations, that applying the compressed mode has a negative impact on the overall system performance. Therefore, another approach is introduced that relies on integrating measurement reports of other systems to support the VHO decision process. The proposal features by continuous operation during information gathering and facilitates reduced power consumption.

Requirements for an integrated system and service 4G architecture

The emerging 4G networks intend to provide a variety of adaptable services to mobile and nomadic users by using an integrated heterogeneous network infrastructure. The commonalities and differences among the various approaches in the integration of 4G systems and services are identified on the basis of an analysis of the research done by well-known international projects. Building on these and other ideas, the requirements for an integrated system and service 4G architecture are defined. Considerations and ideas discussed include AAA functions, network system management, end-to-end QoS negotiation and support, mobility management, adaptability and reconfigurability, support for multiple communication modes, ABC&S, service and access network advertisement, discovery and association, wireless billboard channel, and security and privacy challenges.

Interaction of power control and link adaptation for capacity enhancement and QoS assistance

Within this paper we present a new strategy for applying power control in combination with link adaptation in order to satisfy required quality of service (QoS) parameters and to possibly enhance the overall capacity of HIPERLAN/2 microcellular systems. The efficiency of our algorithm is then investigated and evaluated by means of simulations.

Simulative evaluation of location aided handover in wireless heterogeneous systems

This paper enquires an approach of location aided handover for next generation system integration. For the future only the combination of heterogeneous networks can fulfill the expectations of customers in the sense of ubiquity and bandwidth. Therefore, sophisticated handover and interworking strategies are necessary, in our approach a new entity, called hybrid information system (HIS), gathers status information, like C/I values or free medium capacity, of all associated networks. Thus, a terminal willing to handover has no need to scan the other systems but can simply requests the information from the HIS. To be always connected to the best network regarding the user requirements and to maximize the overall performance it is important to find efficient handover algorithms. We introduce a simulative investigation of the efficiency of a HIS enabled system compared to a legacy solution with direct scanning of potential destination networks.

Enhanced link adaptation performance applying adaptive sub-carrier modulation in OFDM systems

This paper introduces and investigates an enhanced link adaptation scheme considering adaptive sub-carrier modulation and compares this scheme with conventional ones by means of simulations. In order to apply the enhanced link adaptation, firstly adequate switching points with respect to throughput/delay optimisation need to be determined. The performance simulations show that the enhanced link adaptation applies a different switching behaviour, which together with an improved packet error ratio results in a better delay performance.

Performance analysis of resource allocation in wireless multihop networks

Mobile radio systems beyond 3G will comprise one-hop and multihop communication. Analytically derived performance results indicate a potential capacity gain when introducing multihop communication. In this paper a novel resource allocation scheme is presented that beneficially exploits these potentials of relaying by means of concurrent resource scheduling under control of a central station. However, whether multihop communication can be advantageously deployed strongly depends on parameters like noise power, interference, selected modulation and coding scheme, attenuation, and distance between source and destination. These dependencies will be demonstrated by means of analytical performance evaluations taking into account link-level simulations.

Adaptive Beacon Control in a heterogeneous System Environment

The following paper introduces an intelligent way to improve intersystem mobility. Based on location information and link state maps, a specific management unit, referred to as hybrid information system, controls beacon management in one system to enable a terminal in another system to handover. The two options applied include adaptation of the beacon interval and directed beaconing