Forwarding on Gates: A flexible and scalable inter-network layer supporting in-network functions

How to design an inter-network that is flexible regarding its features and scalable at the same time? How can such an inter-network satisfy requirements from applications and subnetworks dynamically? Can routing be more flexible and balance the wishes from end user and network operators? Is there a better world beyond current IP-networks? This book answers these questions by presenting a new architecture called "Forwarding on Gates" (FoG). It exploits the advantages of a recursive reference model and does not follow the traditional OSI reference model. FoG mixes connection-oriented and connectionless aspects dynamically in order to increase its efficiency. It enables a scalable function provisioning by a flexible distribution of states between network participants. Its routing can adjust itself to an optimal trade-off between CPU and memory usage. Moreover, FoG supports new business cases and opens up a market for network-related functions, at which function provider can offer their functions to function users.Auch im Buchhandel erhältlich: Forwarding on Gates : a flexible and scalable inter-network layer supporting in-network functions / Florian Liers Ilmenau : Univ.-Verl. Ilmenau, 2014. - XII, 258 S. ISBN 978-3-86360-094-5 URN urn:nbn:de:gbv:ilm1-2013000657 Preis (Druckausgabe): 30,80

A Novel Opportunistic Spectrum Sharing Scheme for Cognitive Ad Hoc Networks

Nowadays, wireless ad hoc networks are using a static spectrum allocation which leads to congestion in this spectrum parts as the number of devices increases. On the contrary, a significant portion of the spectrum in licensed band (e.g. TV band) is not utilized. Cognitive radio (CR) is a promising technology to solve the spectrum inefficiency problem in ad hoc networks. Based on CR, the unlicensed (secondary) users will utilize the unused spectrum of the licensed (primary) users in an opportunistic manner. As a result, the average spectrum usage will be increased. However, the sudden appearance of primary users will have a negative impact on the performance of secondary users, since secondary users must evacuate the occupied channel and handoff to another unutilized one. This process continues till an unlicensed user finishes his transmission. We will name this process consecutive spectrum handoff (CSH). In order to increase the performance of CR, the number of consecutive spectrum handoffs should be reduced. In this paper, a novel opportunistic spectrum sharing scheme under a heterogeneous spectrum environment of licensed and unlicensed bands is introduced. In this scheme, the licensed channels will be used as operating channels and the unlicensed channels will be used as backup channels when the primary user appears. Since the unlicensed channels are not interrupted by primary users, no more spectrum handoff is needed

The Forwarding on Gates architecture: Flexible placement of QoS functions and states in internetworks

A main driver of Future Internet applications and services is Quality of Service (QoS). Current Internet technologies provide no suitable QoS support for end-to-end connections due to several drawbacks of IntServ and DiffServ. In this article, we propose the “Forwarding on Gates” (FoG) architecture, which answers the QoS questions by the help of a new inter-network architecture. It applies its own new network protocol, which was designed to handle IntServ and DiffServ in an integrated way. FoG supports resource reservations for QoS guarantees in IntServ scenarios and prioritized traffic in DiffServ scenarios as well as a combination of both. As core advantage, the QoS support of FoG works in a scalable way by allowing a network to move QoS states and delegate decisions about the QoS usage to the entities demanding for QoS. This article describes the architecture, its network protocol, and solutions for interoperability with current networks. The evaluation includes theoretical descriptions of network configurations for a use case not supported by IP. Moreover, simulations show that the protocol overhead is comparable to IPv6, although packets can select QoS explicitly. Measured routing graph sizes for various setups show the flexibility of the FoG architecture

A novel opportunistic spectrum sharing scheme for cognitive ad hoc networks

Nowadays, wireless ad hoc networks are using a static spectrum allocation which leads to congestion in this spectrum parts as the number of devices increases. On the contrary, a significant portion of the spectrum in licensed band (e.g. TV band) is not utilized. Cognitive radio (CR) is a promising technology to solve the spectrum inefficiency problem in ad hoc networks. Based on CR, the unlicensed (secondary) users will utilize the unused spectrum of the licensed (primary) users in an opportunistic manner. As a result, the average spectrum usage will be increased. However, the sudden appearance of primary users will have a negative impact on the performance of secondary users, since secondary users must evacuate the occupied channel and handoff to another unutilized one. This process continues till an unlicensed user finishes his transmission. We will name this process consecutive spectrum handoff (CSH). In order to increase the performance of CR, the number of consecutive spectrum handoffs should be reduced. In this paper, a novel opportunistic spectrum sharing scheme under a heterogeneous spectrum environment of licensed and unlicensed bands is introduced. In this scheme, the licensed channels will be used as operating channels and the unlicensed channels will be used as backup channels when the primary user appears. Since the unlicensed channels are not interrupted by primary users, no more spectrum handoff is needed

Quality of experience management for YouTube: clouds, FoG and the AquareYoum

Over the last decade, Quality of Experience (QoE) has become a new, central paradigm for understanding the quality of networks and services. In particular, the concept has attracted the interest of communication network and service providers, since being able to guarantee good QoE to customers provides an opportunity for differentiation. In this paper we investigate the potential as well as the implementation challenges of QoE management in the Internet. Using YouTube video streaming service as example, we discuss the different elements that are required for the realization of the paradigm-shift towards truly user-centric network orchestration. To this end, we elaborate QoE management requirements for two complementary network scenarios (wireless mesh Internet access networks vs. global Internet delivery) and provide a QoE model for YouTube taking into account impairments like stalling and initial delay. We present two YouTube QoE monitoring approaches operating on the network and the end user level. Finally, we demonstrate how QoE can be dynamically optimized in both network scenarios with two exemplary concepts, AquareYoum and FoG, respectively. Our results show how QoE management can truly improve the user experience while at the same time increase the efficiency of network resource allocation

Widespread occurrence of expressed fungal secretory peroxidases in forest soils

Fungal secretory peroxidases mediate fundamental ecological functions in the conversion and degradation of plant biomass. Many of these enzymes have strong oxidizing activities towards aromatic compounds and are involved in the degradation of plant cell wall (lignin) and humus. They comprise three major groups: class II peroxidases (including lignin peroxidase, manganese peroxidase, versatile peroxidase and generic peroxidase), dye-decolorizing peroxidases, and hemethiolate peroxidases (e. g. unspecific/aromatic peroxygenase, chloroperoxidase). Here, we have repeatedly observed a widespread expression of all major peroxidase groups in leaf and needle litter across a range of forest ecosystems (e. g. Fagus, Picea, Acer, Quercus, and Populus spp.), which are widespread in Europe and North America. Manganese peroxidases and unspecific peroxygenases were found expressed in all nine investigated forest sites, and dye-decolorizing peroxidases were observed in five of the nine sites, thereby indicating biological significance of these enzymes for fungal physiology and ecosystem processes. Transcripts of selected secretory peroxidase genes were also analyzed in pure cultures of several litter-decomposing species and other fungi. Using this information, we were able to match, in environmental litter samples, two manganese peroxidase sequences to Mycena galopus and Mycena epipterygia and one unspecific peroxygenase transcript to Mycena galopus, suggesting an important role of this litter-and coarse woody debris-dwelling genus in the disintegration and transformation of litter aromatics and organic matter formation