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Bandwidth Requirements (bandwidth + requirement)

Distribution by Scientific Domains

Engineering	66%

Selected Abstracts

A game-theoretic model for capacity-constrained fair bandwidth allocation

INTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 6 2008
Yonghe Yan
Data stream providers face a hard decision to satisfy the requirements of their subscribers. Each user has a minimum and a maximum required bandwidth. The server should be able to decide which requests can be satisfied and how much bandwidth will be allocated to each. We present a theoretical framework in a distributed mechanism for fair bandwidth allocation on a network with various bottleneck links. In our model, a user is guaranteed a minimum bandwidth and charged a price for the bandwidth allocated. A utility function is defined over the allocated bandwidth for a specific maximum requested bandwidth. We then present a non-cooperative game with social welfare function to resolve users' conflicting bandwidth capacity requests at bottleneck links. We also show that our proposed game-theoretic solution guarantees fair bandwidth allocation as defined in our residual capacity fairness. In order to guarantee the minimum bandwidth requirement, we integrate an admission control mechanism in our solution. However, global optimal admission conditions are not easy to implement for large networks. Therefore, we propose a distributed admission scheme. As a result, the paper presents fair and practical distributed algorithms for bandwidth allocation and admission control in enterprise networks. Our simulation and evaluation study shows that the distributed approach is sufficiently close to the global optimal solution. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Active resource management for the differentiated services environment

INTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 3 2004
Manish Mahajan
This paper presents a mechanism for active resource management (ARM) in a differentiated services environment. While the differentiated services architecture and the bandwidth broker agent provide a mechanism for QoS management through resource reservation, this mechanism is based on a static provisioning of resources. As bandwidth requirement are typically dynamic, such a static reservation approach can either lead to wasted bandwidth or leave applications resource-starved. The active resource management approach presented in this paper addresses this problem by dynamically reallocating resources based on current network state and applications requirements. An implementation and evaluation of ARM using the NS-2 simulation toolkit is also presented.,Copyright © 2004 John Wiley & Sons, Ltd. [source]

Resource management model and performance evaluation for satellite communications

INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 2 2001
Axel Jahn
Abstract Efficient resource management is mandatory to achieve maximum system capacity for next generation communications systems. Resource management deals with the available spectral band, time, power, and space for a transmission signal. It includes (i) the frequency planning, (ii) the selection of transmit power, and (iii) the assignment of the channels and access nodes to the users. The paper presents a generalized notation as well as graph algorithms for resource management problems. Impairment graphs can be used for frequency planning, whereas flow graphs are suitable for channel access problems. To evaluate the performance of the resource management, service criteria (such as blocking or the carrier to interference ratio C/I) or efficiency criteria (bandwidth requirements) can be derived from the graphs. The resource management techniques are applied to satellite networks with non-geostationary orbits yielding time-variant network topologies. As a simple example, the channel assignment and capacity optimization of the EuroSky Way system are shown. Furthermore, a comparison of fixed, dynamic and hybrid channel allocation schemes (FCA, DCA, HCA) for a typical MEO satellite scenario is given. Satellite diversity and its impact on bandwidth requirement and transmission quality is also examined. Finally, it is shown how spread spectrum systems can be investigated with the presented tools. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Modeling and optimization of cylindrical antennas using the mode-expansion method and genetic algorithms

INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 6 2005
Dawei Shen
Abstract For monopole antennas with cylindrically symmetric structures, a mode-expansion method is highly time efficient, which is a realistic approach for integrating function-optimization tools, such as genetic algorithms (GAs), in order to extract the best bandwidth property. In this article, a mode-expansion method is used to simulate the impedance characteristics of the cylindrical antennas. As examples, two new types of monopole antennas are presented, one of which possesses a two-step top-hat structure while the other has an annulus around the stem. After the modeling scheme is examined for convergence and data validity, the associated optimization problem, with dimensions as decision variables, structural limitations as linear constraints, and desired bandwidth performance as an objective function, is solved using GAs. The effects of the geometric parameters on the impedance characteristics are investigated in order to demonstrate the optimality of the calculated solutions. Two optimized practical antennas are designed based on our numerical studies. One has a broad bandwidth of 3 GHz while the other shows a dual-band property, which can satisfy the bandwidth requirements for both Bluetooth (2.45-GHz band) and WLAN (5-GHz band) systems. © 2005 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005. [source]

Resource management model and performance evaluation for satellite communications

A coupling element-based quad-band antenna structure for mobile terminals

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 6 2007
Juha Villanen
Abstract A novel internal coupling element-based antenna structure for quad-band mobile terminals is presented. The antenna structure comprises of two nonresonant coupling elements, a multi-resonant matching circuitry, and the chassis of the mobile terminal. The coupling elements occupy an extremely low volume of only 0.7 cm3, and they have a very low profile of only 4 mm. Despite of the low volume and low profile of the antenna structure, it can fulfill the bandwidth requirements of the GSM850/900 and GSM1800/PCS1900 systems with sufficiently high efficiency, thus making it a promising antenna candidate for future mobile terminals. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 1277,1282, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22463 [source]

Planar slot antenna with PBG filter for wireless communications

MICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 3 2007
Fabrizio Consoli
Abstract A planar circular slot antenna, integrated with a band-stop photonic bandgap filter is presented here. The complete realized prototype is suitable to cover the bandwidth requirements of many wireless communication standards in one solution. The work describes the detailed study of both the antenna and the PBG filter properties. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 551,555, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22191 [source]

Harmonic broadcasting is bandwidth-optimal assuming constant bit rate

NETWORKS: AN INTERNATIONAL JOURNAL, Issue 3 2006
Lars Engebretsen
Abstract Harmonic broadcasting was introduced by Juhn and Tseng in 1997 as a way to reduce the bandwidth requirements required for video-on-demand broadcasting. In this article, we note that harmonic broadcasting is actually a special case of the priority encoded transmission scheme introduced by Albanese et al. in 1996, and prove,using an information theoretic argument,that it is impossible to achieve the design goals of harmonic broadcasting using a shorter encoding. © 2006 Wiley Periodicals, Inc. NETWORKS, Vol. 47(3), 172,177 2006 [source]

A slotted multicode CDMA protocol for efficient integration of voice and data in cellular networks

INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 6 2002
H. Zhang
Abstract This paper presents a novel radio channel structure based on slotted CDMA technology intended for carrying traffic with diverse bandwidth/QoS requirements in mobile environments, e.g. personal communication systems (PCS). The essence of our approach is a combination of flexible slotting with allocation of multiple codes to high-bandwidth mobiles. As demonstrated by our performance studies, the proposed scheme efficiently integrates multiple traffic classes into a unified CDMA system. It is highly flexible and incurs low overheads for a wide range of realistic traffic conditions. Copyright © 2002 John Wiley & Sons, Ltd. [source]