793 research outputs found
QoS multicast tree construction in IP/DWDM optical internet by bio-inspired algorithms
Copyright @ Elsevier Ltd. All rights reserved.In this paper, two bio-inspired Quality of Service (QoS) multicast algorithms are proposed in IP over dense wavelength division multiplexing (DWDM) optical Internet. Given a QoS multicast request and the delay interval required by the application, both algorithms are able to find a flexible QoS-based cost suboptimal routing tree. They first construct the multicast trees based on ant colony optimization and artificial immune algorithm, respectively. Then a dedicated wavelength assignment algorithm is proposed to assign wavelengths to the trees aiming to minimize the delay of the wavelength conversion. In both algorithms, multicast routing and wavelength assignment are integrated into a single process. Therefore, they can find the multicast trees on which the least wavelength conversion delay is achieved. Load balance is also considered in both algorithms. Simulation results show that these two bio-inspired algorithms can construct high performance QoS routing trees for multicast applications in IP/DWDM optical Internet.This work was supported in part ny the Program for New Century Excellent Talents in University, the Engineering and Physical Sciences Research Council (EPSRC) of UK under Grant EP/E060722/1, the National Natural Science Foundation of China under Grant no. 60673159 and 70671020, the National High-Tech Reasearch and Development Plan of China under Grant no. 2007AA041201, and the Specialized Research Fund for the Doctoral Program of Higher Education under Grant no. 20070145017
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Integration of unidirectional technologies into wireless back-haul architecture
This thesis was submitted for the degree of Docter of Philosophy and awarded by Brunel University.Back-haul infrastructures of today's wireless operators must support the triple-play services demanded by the market or regulatory bodies. To cope with increasing capacity demand, the EU FP7 project CARMEN has developed a cost-effective heterogeneous
multi-radio wireless back-haul architecture, which may also leverage the native multicast
capabilities of broadcast technologies such as DVB-T to off-load high-bandwidth broadcast
content delivery. However, the integration of such unidirectional technologies into a packet-switched architecture requires careful considerations. The contribution of this thesis is the investigation, design and evaluation of protocols and mechanisms facilitating the integration of such unidirectional technologies into the wireless
back-haul architecture so that they can be configured and utilized by the spectrum and
capacity optimization modules. This integration mainly concerns the control plane and, in particular, the aspects related to resource and capability descriptions, neighborhood, link and Multi Protocol Label Switching (MPLS) Label-Switched Path (LSP) monitoring, unicast and multicast LSP signalling as well as topology forming and maintenance. During the course of this study we have analyzed the problem space, proposed solutions to the resulting research questions and evaluated our approach. Our results show that the now Unidirectional Technology (UDT)-aware architecture can readily consider
Unidirectional Technologies (UDTs) to distribute, for example, broadcast content
Xcast Based Routing Protocol For Push To Talk Application In Mobile Ad Hoc Networks
Mobile ad-hoc networks comprise a type of wireless network that can be easily
created without the need for network infrastructure or administration. These
networks are organized and administered into temporary and dynamic network
topologies. Unfortunately, mobile ad-hoc networks suffer from some limitations
related to insufficient bandwidth. The proliferation of new IP Multimedia subsystem
services (IMs), such as Push-to-talk (PTT) applications consume large amounts of
bandwidth, resulting in degraded QoS performance of mobile ad-hoc networks. In
this thesis, a Priority XCAST based routing protocol (P-XCAST) is proposed for
mobile ad-hoc networks to minimize bandwidth consumption. P-XCAST is based on
demand route requests and route reply mechanisms for every destination in the PXCAST
layer. To build the network topology and fill up the route table for nodes,
the information in the route table is used to classify the XCAST list of destinations
according to similarities on their next hop. Furthermore, P-XCAST is merged with a
proposed Group Management algorithm to handle node mobility by classifying nodes
into two types: group head and member. The proposed protocol was tested using the
GloMoSim network simulator under different network scenarios to investigate
Quality of Service (QoS) performance network metrics. P-XCAST performance was
better by about 20% than those of other tested routing protocols by supporting of
group size up to twenty receivers with an acceptable QoS. Therefore, it can be
applied under different network scenarios (static or dynamic). In addition Link
throughput and average delay was calculated using queuing network model; as this
model is suitable for evaluating the IEEE 802.11 MAC that is used for push to talk applications. The analytical results for link throughput and average delay were used
to validate the simulated results
Topology forming and optimization framework for heterogeneous wireless back-haul networks supporting unidirectional technologies
Wireless operators, in developed or emerging regions, must support triple-play service offerings as demanded by the market or mandated by regulatory bodies through so-called Universal Service Obligations (USOs). Since individual operators might face different constraints such as available spectrum licenses, technologies, cost structures or a low energy footprint, the EU FP7 CARrier grade wireless MEsh Network (CARMEN) project has developed a carrier-grade heterogeneous multi-radio back-haul architecture which may be deployed to extend, complement or even replace traditional operator equipment. To support offloading of live triple-play content to broadcast-optimized, e.g., DVB-T, overlay cells, this heterogeneous wireless back-haul architecture integrates unidirectional broadcast technologies. In order to manage the physical and logical resources of such a network, a centralized coordinator approach has been chosen, where no routing state is kept at plain WiBACK Nodes (WNs) which merely store QoS-aware MPLS forwarding state. In this paper we present our Unidirectional Technology (UDT)-aware design of the centralized Topology Management Function (TMF), which provides a framework for different topology and spectrum allocation optimization strategies and algorithms to be implemented. Following the validation of the design, we present evaluation results using a hybrid local/centralized topology optimizer showing that our TMF design supports the reliable forming of optimized topologies as well as the timely recovery from node failures.Federal Ministry of Education and Research of the Federal Republic of German (F¨orderkennzeichen 01 BU1116,SolarMesh Energieeffizientes,autonomesgroßfl¨achiges
Sprach- undDatenfunknetzmitflacher IP-Architektur
Security and Privacy Issues in Wireless Mesh Networks: A Survey
This book chapter identifies various security threats in wireless mesh
network (WMN). Keeping in mind the critical requirement of security and user
privacy in WMNs, this chapter provides a comprehensive overview of various
possible attacks on different layers of the communication protocol stack for
WMNs and their corresponding defense mechanisms. First, it identifies the
security vulnerabilities in the physical, link, network, transport, application
layers. Furthermore, various possible attacks on the key management protocols,
user authentication and access control protocols, and user privacy preservation
protocols are presented. After enumerating various possible attacks, the
chapter provides a detailed discussion on various existing security mechanisms
and protocols to defend against and wherever possible prevent the possible
attacks. Comparative analyses are also presented on the security schemes with
regards to the cryptographic schemes used, key management strategies deployed,
use of any trusted third party, computation and communication overhead involved
etc. The chapter then presents a brief discussion on various trust management
approaches for WMNs since trust and reputation-based schemes are increasingly
becoming popular for enforcing security in wireless networks. A number of open
problems in security and privacy issues for WMNs are subsequently discussed
before the chapter is finally concluded.Comment: 62 pages, 12 figures, 6 tables. This chapter is an extension of the
author's previous submission in arXiv submission: arXiv:1102.1226. There are
some text overlaps with the previous submissio
Towards QoS provisioning in a heterogeneous carrier-grade wireless mesh access networks using unidirectional overlay cells
Proceedings of: 6th International ICST Conference on Heterogeneous Networking for Quality, Reliability, Security and Robustness, QShine 2009 and 3rd International Workshop on Advanced Architectures and Algorithms for Internet Delivery and Applications, AAA-IDEA 2009, Las Palmas, Gran Canaria, November 23-25, 2009The visibility and success ofWireless Mesh Network (WMN)
deployments has raised interest among commercial operators in this technology.
Compared to traditional operator access networks WMNs have
the potential to offer easier deployment and flexible self-reconfiguration
at lower costs. A WMN-type architecture considered as an alternative
for an operator access network must meet similar requirements such as
high availability and guaranteed QoS in order to support triple-play content
provisioning. In this paper we introduce an architecture of such a
Carrier-grade Wireless Mesh Access Network (CG-WMAN). We then
present our contribution, an approach to seamlessly integrate unidirectional
broadcast cells (i.e. DVB-T) into such a CG-WMAN. This allows
higher layer protocols to utilize broadcast cells like regular mesh links,
where beneficial for a given payload and receiver distribution. We then
present a typical use case and discuss for which combinations of traffic
type, user distribution and QoS requirements the use of longer range
broadcast technologies can help to improve the overall CG-WMAN performance
in terms of throughput and reliability.European Community's Seventh Framework ProgramPublicad
Quality of Service over Specific Link Layers: state of the art report
The Integrated Services concept is proposed as an enhancement to the current Internet architecture, to provide a better Quality of Service (QoS) than that provided by the traditional Best-Effort service. The features of the Integrated Services are explained in this report. To support Integrated Services, certain requirements are posed on the underlying link layer. These requirements are studied by the Integrated Services over Specific Link Layers (ISSLL) IETF working group. The status of this ongoing research is reported in this document. To be more specific, the solutions to provide Integrated Services over ATM, IEEE 802 LAN technologies and low-bitrate links are evaluated in detail. The ISSLL working group has not yet studied the requirements, that are posed on the underlying link layer, when this link layer is wireless. Therefore, this state of the art report is extended with an identification of the requirements that are posed on the underlying wireless link, to provide differentiated Quality of Service
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