Jörg Eberspächer

IP based enhanced data casting services over radio broadcast networks

Emerging technologies like ATM, WDM or xDSL enable broadband communication over wireline networks. Mobile data systems like GSM or even UMTS are lacking in bandwidth for broadband multimedia. Furthermore, the emergence of Internet information systems like the WWW increases the desire for broadband multimedia information and communication services and also for wireless, i.e. mobile users. The system architecture, which is described, enables the realization of broadband multimedia information services for mobile users. The basic idea for the wireless provision of multimedia services to the users is the usage of digital radio and television broadcast networks like DVB-T (Digital Video Broadcast-Terrestrial) or DAB (Digital Audio Broadcast). Though these networks only support unidirectional data casting, they provide sufficient bandwidth for multimedia information services with a large number of users. An interaction channel for upstream communication to request information is integrated in the system using different approaches with GSM data services. The system architecture is structured in components with standardized interfaces to be flexible in regard of the realization of a specific service. The Internet protocol (IP) is the basic means of interconnection for our system to form a flexible multiservice network. The system architecture has already been implemented in a prototype information service system, which enables WWW access over DVB-T and is on its way to becoming a product.

Multiperiod Planning for Optical Networks - Approaches Based on Cost Optimization and Limited Budget

Multiperiod network planning is, especially for cost intensive and long term operated core networks, a necessity to provide cost efficient long term solutions. In this paper we give an overview on commonly used multiperiod planning approaches and compare their cost allocations and dependencies on cost decreasing factors. Furthermore, we propose a new multiperiod approach, which aims at a complete new orientation: Instead of minimizing network costs, a restricted budget is used not only to satisfy occurring demand but also to purchase equipment for future demand requests. With this approach we obtain long term solutions for optical networks with a restricted budget. This Budget-Restricted approach has a strong relation to applications in industry and public authorities. We use for our studies an integer linear optimization model which takes cost optimal routing and also the wavelength assignment into account. Additionally we provide a detailed cost function with a special interest on node costs.

5. First and Second Generation of Peer-to-Peer Systems

Peer-to-Peer (P2P) networks appeared roughly around the year 2000 when a broadband Internet infrastructure (even at the network edge) became widely available. Other than traditional networks Peer-to-Peer networks do not rely on a specific infrastructure offering transport services. Instead they form “overlay structures” focusing on content allocation and distribution based on TCP or HTTP connections. Whereas in a standard Client-Server configuration content is stored and provided only via some central server(s), Peer-to-Peer networks are highly decentralized and locate a desired content at some participating peer and provide the corresponding IP address of that peer to the searching peer. The download of that content is then initiated using a separate connection, often using HTTP. Thus, the high load usually resulting for a central server and its surrounding network is avoided leading to a more even distribution of load on the underlying physical network. On the other hand, such networks are typically subject to frequent changes because peers join and leave the network without any central control.

Intelligent Wireless Communication for Future Autonomous and Cognitive Automobiles

Communication between vehicles based on ad-hoc networking principles has become a prominent research area. The main difficulties in designing such vehicle-to-vehicle (V2V) networks arise from the lack of infrastructure, necessitating fully distributed functionalities and self-organizing capabilities, and from their highly dynamic nature due to the mobility of nodes. A new research goal is to use V2V networks to realize autonomous vehicles which can cooperate in terms of cognition and trajectory planning while participating in traffic. This specific scenario imposes additional and very strict requirements on the communication network design. In this paper we present the requirements for the communication system and its security. Additionally, we present the essential building blocks and mechanisms to tune existing technologies for use in the autonomous vehicles scenario.

Increasing the reliability of structured P2P networks

Third generation P2P networks try to reduce the high signaling overhead observed in unstructured P2P networks by means of proactive routing. Therefore, a deterministically structured overlay network is established between the participating peers by making use of distributed hash tables (DHT). To ensure the correct execution of lookups it is crucial to keep up the network structure. The Chord protocol already proposes an efficient stabilize algorithm that works well in networks with low churn rates. However, as nodes join and leave the network more frequently, inconsistencies within the network structure appear, because the network is not capable of reacting fast enough to all changes in the topology. In this paper the authors proposed a modified stabilize algorithm that is based on available token techniques from ring networks. While decreasing the overhead in the network, a more stable overlay structure is established.

Adaptive radio resource management in F/TDMA cellular networks using smart antennas

In this paper we discuss different Radio Resource Management (RRM) strategies for smart antenna cellular networks. The focus is on adaptive strategies which combine spatial channel reuse within the cell with dynamic inter-cell channel allocation. In particular, three different SDMA channel allocation strategies are described and compared in terms of complexity as well as traffic capacity. The comparison is done by means of system simulations of a multi-cellular environment. We show that with a growing degree of freedom the RRM strategies yield better results in terms of traffic capacity while the number of handoffs per call increases and the complexity grows.

Service cost modeling and cost comparative study

Today, network operators are under high pressure from market competition and hence, they are trying constantly to increase their revenue and to reduce their cost. Operational Expenditures (OpEx) are therefore gaining attention, since they highly impact the overall cost of the network. OpEx can be divided into (i) network operation related OpEx and (ii) service handling related OpEx. This paper investigates the influence of services on OpEx, focusing on Ethernet services in future network architectures. Control and management capabilities of different network platforms, which will be used for the service production, will impact the service costs (i.e. the more capabilities, the less expensive they should be). This paper shows the cost differences when establishing and releasing future Ethernet services using different platforms for different types of services (i.e. point-to-point, point-to-multipoint or multipoint-to-multipoint).

3. Past and Future

Within the last few years, starting with the introduction of Napster in May 1999, the disruptive technology of Peer-to-Peer networking has encountered an enormous growth. Today the traffic caused by Peer-to-Peer networks represents a significant portion in the Internet. For example in the German Research Network (Deutsches Forschungsnetz DFN) Peer-to-Peer causes up to 60 percent of the traffic [210]. Similar trends can be observed in other networks e.g. in the Abilene backbone [42].

A Convergence Architecture for GRID Computing and Programmable Networks

GRID computing in the Internet faces two fundamental challenges. First the development of an appropriate middleware for provision of computing services in a scalable and secure manner. Second the distributed, scalable and fast connection of GRID processing components to the network. The latter is important to enable fast data exchange among the distributed components of virtualized super-computers.