1,721,100 research outputs found
Queuing Theory and Telecommunications: Networks and Applications
No full textQueuing Theory and Telecommunications : Networks and Applications provides some fundamental knowledge in queuing theory, as well as essential analytical methods and approaches to be employed to evaluate and design telecommunication networks. This work provides methods for teletraffic analysis as well as descriptions of current network technologies such as ISDN, B-ISDN, IP-based networks, MPLS, GMPLS, NGN and local access systems, including ADSL-based, Ethernet, Token Passing, and WiFi. Also, numerous solved exercises are provided in order to illustrate the applications of queuing theory in telecommunication networks. The following advanced telecommunication problems are modeled and solved by means of queuing analysis: statistics of the transmission delay for packet data traffic arriving at a transmission buffer; blocking behavior for bursty call arrival processes; characterization of Markovian traffic sources; performance of traffic regulators, analysis of access protocols and more. The author provides readers with a correct understanding of fundamental methods to be applied in the analysis of telecommunications systems. Queuing Theory and Telecommunications : Networks and Applications is a reference text for advanced undergraduate and graduate level courses in telecommunications engineering and networking. It will also serve as a useful work for system engineers involved in network dimensioning. © 2005 Springer Science+Business Media, Inc. All rights reserved
Resource Management in Satellite Networks: Optimization and Cross-Layer Design
No full textResource Management in Satellite Networks: Optimization and Cross-Layer Design addresses the emergent research area of cross-layer air interface design for satellite systems. A detailed analysis of cross-layer methods is presented along with new analytical and simulation results demonstrating that these techniques can assures high QoS levels for differentiated traffic classes. The research presented integrates the expertise of a wide range of researchers, and addresses all aspects of system design (e.g., propagation issues, resource management techniques, link design, QoS, transport protocols, etc.). Of particular importance is the inclusion of research applicable to both fixed and mobile satellite systems. Resource Management in Satellite Networks: Optimization and Cross-Layer Design is based on the work of the SatNEx Network of Excellence. Since its inception in January 2004, SatNEx has focused on the investigation of cross-layer design issues, which have since emerged to form a distinct field of research. More than 14 partner organizations and institutions participated in this research.This book will serve as a reference for systems engineers and satellite network engineers as well as researchers and graduate students in the field of satellite communications. © 2007 Springer Science+Business Media, LLC. All rights reserved
Queuing theory and telecommunications: networks and applications
No full textThis book provides a basic description of current networking technologies and protocols as well as important tools for network performance analysis based on queuing theory. The second edition adds selected contents in the first part of the book for what concerns: (i) the token bucket regulator and traffic shaping issues; (ii) the TCP protocol congestion control that has a significant part in current networking; (iii) basic satellite networking issues; (iv) adding details on QoS support in IP networks. The book is organized so that networking technologies and protocols (Part I) are first and are then followed by theory and exercises with applications to the different technologies and protocols (Part II). This book is intended as a textbook for master level courses in networking and telecommunications sectors
Cross-layer issues in DVB-S2/-RCS and BSM model
No full textSatellite communications are experiencing a renewed interest. This paper deals with possible cross-layer approaches requiring a modification of protocol layers in the design phase as well as new dynamic interactions and adaptations. An IP satellite network has been considered that is based on the DVB-S2/-RCS standard where, according to the BSM protocol architecture, the SI-SAP interface and related primitives are used to connect higher protocol layers with lower (MAC and PHY) ones. The interest is here on cross-layering and BSM primitives. A case study is proposed with related signaling for a TCP-aware DAMA scheme
Resource management in hybrid DVB-RCS and WiFi networks
No full textSatellite networks are an attractive solution to provide broadband communication services anytime, anywhere with quality of service support. The aim of this paper is to study the integration of GEO satellite networks, DVB-RCS-based, with WiFi networks. This is particularly important in emergency scenarios where reliable satellite networks could be integrated with WiFi systems for local mobility support. In this paper, a combined-dynamic resource management scheme, CRA & A/VBDC, is investigated for the satellite segment to support VoIP and FTP elephant connections. A corresponding QoS differentiation is considered in the WiFi segment, based on the IEEE 802.11e standard; in particular, a suitable traffic class mapping is proposed for an efficient interconnection of the DVB-RCS segment with the WiFi one. The obtained results prove the efficiency achieved by the proposed dynamic approach as the number of terminals increases, the good performance obtained with Scalable TCP and the importance of the proposed traffic mapping in the WiFi segment
Performance evaluation of scalable TCP and HighSpeed TCP over geostationary satellite links
No full textIn this paper we analyse the performance in a satellite environment of two recently proposed modifications to the TCP's congestion control algorithm, namely Scalable TCP and Highspeed TCP. These two protocols, originally designed for high-speed backbone links, appear to be major candidates for replacing in the next-generation Internet the current congestion control mechanism implemented by standard TCP. In this paper, we evaluate by means of ns2 simulations the performance of such protocols in a static as well as a mobile satellite environment. The results confirm that both protocols, and particularly S-TCP, may represent a viable alternative to standard TCP also in a satellite environment. © 2005 IEEE
Internet access in hybrid terrestrial and satellite mobile communication systems
No full textSatellite systems will play a significant role in the provision of broadband transmissions to mobile users. This paper deals with a hybrid network architecture with a geostationary satellite for downlink high bit-rate transmissions and a terrestrial 3G return link both to account for the limited power available on mobile terminals and to exploit the lower propagation delays of the terrestrial path. We have considered that both TCP traffic and UDP one is destined to a dual-band mobile terminal. A suitable routing configuration has been employed to support this hybrid network that has been implemented in a simulator under the ns2 environment. The obtained results have permitted to compare the performance of different TCP versions (i.e., NewReno, SACK and Westwood) also including the possibility to adopt ARQ on the satellite link. We have shown the TCP goodput advantages of the hybrid scenarios with respect to the case where both downlink and uplink are via satellite. Finally, we have obtained that TCP Westwood permits to achieve the best performance
Mode adaptivity in broadcast wireless networks
No full textThis paper deals with the proposal of a novel resource management scheme for efficient downlink transmissions in broadband wireless systems with synchronous base stations. Such technique is able to vary dynamically the transmission characteristics and the resource allocation in order to guarantee suitable quality of service levels for both high-quality video streaming traffic and heavy Web downloading one. Our strategy, named Dynamic - Priority and Mode Selection (D-PMS), allows superior performance with respect to a previously proposed solution in the literature
Qos in hybrid WiFi and DVB-RCS networks
No full textNowadays there is an increasing need of broadband communications anytime, anywhere for users requiring multimedia services with quality of service support. This paper deals with the integration of GEO satellite networks and terrestrial wireless networks. Our interest is for a DVB-RCS GEO system integrated with a WiFi terrestrial segment based on the IEEE 802.11b and e standards. Such a scenario is particularly relevant for the provision of multimedia interactive services in emergency areas. In this paper, we focus on a satellite DAMA strategy with related MAC buffer sizing, on the support of FTP and VoIP traffic flows, and on the traffic mapping with the WiFi segment. An ns-2-based simulation tool has been developed that permits to achieve a fine understanding on TCP-MAC interactions in terms of frame and buffer sizes. Finally, referring to the Skyplex DVB-RCS payload on board of HotBird 6 GEO satellite, simulation results have permitted to show the good utilization of resources with the considered DAMA strategy for FTP traffic flows
Scalable TCP over satellite links: Performance issues and cross-layer design
No full textIn this work, we analyze some issues related to the performance of a recently proposed TCP enhancement, Scalable TCP (S-TCP), over satellite links. We first discuss S-TCP features and assess its performance in satellite networks, by means of numerical simulations, for a wide range of conditions (fixed users, mobile users, rainy days). Then, we analyze the impact of S-TCP protocol parameters in a satellite environment, and provide guidelines for their setting in order to improve the system performance. Finally, we present some possible enhancements deriving from the adoption of erasure codes at the link level (in a cross-layer perspective). In particular, TCP/FEC interactions are analyzed and the optimal operating point is derived
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