The Experts below are selected from a list of 145719 Experts worldwide ranked by ideXlab platform
Leonid G. Kazovsky - One of the best experts on this subject based on the ideXlab platform.
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Broadband Optical Access Networks - Hybrid Optical–Wireless Access Networks
Proceedings of the IEEE, 2012Co-Authors: Leonid G. Kazovsky, Shing Wa Wong, Tolga Ayhan, Kadir M. Albeyoglu, Moises R. N. Ribeiro, Anujit ShastriAbstract:Next-generation Access networks are expected to provide mobility, large data bandwidth, high quality of service (QoS), and ubiquitous coverage. Hybrid optical-Wireless Access networks will support these complementary features through high-capacity fiber subnetworks and flexible Wireless subnetworks. As Wireless Access technologies progress, increased demand for Access bandwidth and QoS will require a rapid evolution of fiber subnetworks and a tighter integration of the two technologies. This paper presents both radio-over-fiber transport technologies and novel architectures and technologies for hybrid optical-Wireless networking. Basic optical systems for radio signals' transport use intensity modulation and direct detection. Advanced transport systems may utilize amplified links, coherent links, subcarrier transport, and digitized transport. They can be used to support powerful Access solutions. On the networking side, diverse alternatives for hybrid Access architectures are presented. Two wavelength division multiplexing (WDM)-based architectures, MARIN and GROWNet, are analyzed in detail. Both architectures dynamically support next-generation Wireless Access network traffic employing reconfigurable WDM technologies. MARIN is more technologically conservative and so is more suitable for near-future implementation. GROWNet is more technologically aggressive and is substantially more flexible and more powerful. Using hybrid network simulations, we demonstrate these architectures' capabilities to dynamically balance Wireless traffic and to coordinate Wireless transmission. We also review other research efforts in this field including ACCORDANCE, FiWi, FUTON, and WOBAN. Remaining challenges and research topics are also discussed to motivate further investigations into optical-Wireless Access networks.
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MARIN hybrid optical-Wireless Access network
OFC/NFOEC 2007 - Optical Fiber Communication and the National Fiber Optic Engineers Conference 2007, 2007Co-Authors: Wei Tao Shaw, Shing Wa Wong, Ning Cheng, Leonid G. KazovskyAbstract:A novel hybrid optical-Wireless Access network is proposed for metropolitan area. This novel architecture consists of Wireless mesh networks and a reconfigurable optical backhaul and aggregation network based on TDM-PON technology.
C. Charnsripinyo - One of the best experts on this subject based on the ideXlab platform.
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Design of survivable Wireless Access networks
2003Co-Authors: David Tipper, C. CharnsripinyoAbstract:The survivability of Wireless Access networks has become a critical issue due to the rapidly increasing dependence on Wireless mobile services. However, little emphasis has been placed on understanding and improving the survivability of Wireless Access networks. In this dissertation, a multilayer survivability framework is presented in order to facilitate the development of effective techniques for building survivable Wireless Access networks. The results of a simulation-based survivability analysis are given to determine the impact of various failure scenarios in Wireless Access networks. This dissertation proposes new techniques for survivable Wireless Access network design. The goal is to provide an effective solution for Wireless Access network design that satisfies traffic and survivability requirements while minimizing the network design cost of the Wireless backhaul network. Three different approaches to creating a survivable network topology for second generation Wireless Access networks are considered namely: (1) a mesh-based restorable network, (2) a multi-ring network, and (3) a hybrid mesh-ring network. Network design problems are formulated as mathematical optimization models for each of the three approaches. A novel aspect of the proposed work is the incorporation of the effect of user mobility after a failure in the network design model. Numerical results show that, among the three different network design approaches considered, a mesh-based restorable network design is the most cost-efficient. A two-phase design methodology is developed to solve the mesh-based restorable network design problem. The first phase provides a minimum-cost, initial network design that can satisfy the traffic requirements of the network. The second phase provides an incremental approach to augmenting the minimum cost network topology from phase one in order to satisfy survivability requirements. The proposed two-phase model for a mesh restorable network design can be easily applied to both new and existing Wireless Access networks to improve their survivability. This dissertation also proposes an efficient heuristic algorithm to solve the mesh-based network design problem using a minimum-cost routing technique. The proposed heuristic can efficiently find near-optimal solutions compared to the solutions obtained from a standard optimization technique for small problem-size networks. More importantly, the algorithm is shown to scale to solve the mesh-based network design problem in large problem-size networks within a reasonable amount of time. Lastly, the proposed two-phase mesh network design model and heuristic algorithm can be applied to the design of emerging third-generation Wireless Access networks. Experimental results show that the two-phase mesh network design model and heuristic algorithm yield reasonable solutions.
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Topological design of 3G Wireless Access networks
2004 IEEE Region 10 Conference TENCON 2004., 1Co-Authors: C. CharnsripinyoAbstract:Wireless Access networks have importantly become a part of the telecommunication infrastructure that provides voice, data and multimedia services to mobile users. As traffic increasingly becomes data instead of voice, existing Wireless Access networks need an appropriate and efficient infrastructure for the delivery of bursty data packet services. This paper presents a network optimization model for topological design of 3G Wireless Access networks. The main objective of the model is to optimize the network design cost of 3G Wireless backhaul networks with acceptable quality of service requirements. This paper also presents an efficient heuristic method to solve large network design problem sizes within a reasonable computational time while obtaining a near optimal solution.
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Designing fault tolerant Wireless Access networks
MILCOM 2002. Proceedings, 1Co-Authors: C. Charnsripinyo, David TipperAbstract:Providing fault tolerance in Wireless Access networks has become crucial as user dependence on mobile services increases, especially for business and emergency services. Unlike wired Access networks, fault tolerant Wireless network design can be costly, and highly complicated due to unique characteristics of Wireless mobile networks, such as user mobility, that can significantly worsen network performance after failures. We present a novel network design model that incorporates the effect of user mobility for fault-tolerant Wireless Access networks. The problem was formulated as an integer programming (IP) model to minimize the total network interconnect cost while user demands and survivability requirements are satisfied.
H. Ogawa - One of the best experts on this subject based on the ideXlab platform.
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Millimeter-wave Wireless Access systems
APMC 2001. 2001 Asia-Pacific Microwave Conference (Cat. No.01TH8577), 2001Co-Authors: H. OgawaAbstract:The millimeter-wave frequencies from 40 GHz to 60 GHz bands will become very important for broadband signal transmission in both outdoor and indoor environments. Millimeter-wave Wireless Access systems which are being investigated in Communication Research Laboratory are overviewed. The broadband fixed Wireless Access (FWA) system, pedestrian-type mobile Access system, and indoor home Wireless Access system are presented.
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Millimeter-wave indoor/outdoor Wireless Access systems and their technologies
Radio and Wireless Conference 2003. RAWCON '03. Proceedings, 1Co-Authors: H. OgawaAbstract:Millimeter-wave Wireless Access systems which are being investigated in Communication Research Laboratory, Incorporated Administrative Agency are overviewed. The broadband millimeter-wave Access systems which are fixed Wireless Access (FWA) systems are first discussed, and the video distribution system, vertically connected Wireless link and the ad hoc system are also presented.
Hikmet Sari - One of the best experts on this subject based on the ideXlab platform.
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Broadband Wireless Access: Technical Challenges, Standards and Technologies
WiMAX London 2007, 2007Co-Authors: Hikmet SariAbstract:The article consists of a Powerpoint presentation on broadband Wireless Access. The areas discussed include: broadband Wireless Access and evolution of requirements from fixed to mobile services; the BWA channel; WiMaX Forum and IEEE 802.16 specifications; transmission and multiple Access technologies: OFDM, single-carrier transmission (SCT) and OFDMA; multiple antenna (MIMO) options and tradeoffs; link adaptation. (36 pages)
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Encyclopedia of Telecommunications - Broadband Wireless Access
Wiley Encyclopedia of Telecommunications, 2003Co-Authors: Hikmet SariAbstract:Broadband Wireless Access (BWA) is an Access technology that is particularly suited to new operators without an existing infrastructure to serve the end users. It is in direct competition with incumbent telecom operators' digital subscriber lines (DSL) and cable operators' cable modem technology. BWA systems make use of millimeter-wave radio frequencies above 20 GHz as well as of microwave frequencies between 2 and 11 GHz. BWA systems at millimeter-wave frequencies are often referred to as Local Multipoint Distribution Service (LMDS) systems. While LMDS systems are designed for line-of-sight (LOS) propagation and use small cell sizes, BWA Access systems at lower microwave frequencies are designed for non-LOS propagation and typically use much larger cell sizes. In this article, we present the basic characteristics of both types of BWA networks, describe the technologies used and the current standardization work in this field by the IEEE 802.16 Group in the US and the ETSI in Europe. Keywords: broadband Wireless Access; fixed Wireless Access; MMDS; LMDS
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Trends and challenges in broadband Wireless Access
IEEE Benelux Chapter on Vehicular Technology and Communications. Symposium on Communications and Vehicular Technology. SCVT-2000. Proceedings (Cat. No, 1Co-Authors: Hikmet SariAbstract:This paper gives an overview of broadband Wireless Access systems, discusses the current trends, and highlights the major technical challenges for future systems. The study covers local multipoint distribution service (LMDS) networks that operate at millimeter wave radio frequencies above 20 GHz, as well as broadband Wireless Access at microwave frequencies below 11 GHz. We outline the current standardization work in this field by the ETSI in Europe and the IEEE 802.16 Group in the US. We point out that one of the major problems is the intercell interference which limits the frequency reuse factor and the cell capacity. We address the issue of increasing cell capacity using adaptive modulation, code-division multiple Access (CDMA), and adaptive antennas. We also discuss the basic transmission technologies for lower frequency bands (below 11 GHz) where a significant amount of multipath propagation must be compensated.
L.g. Sutliff - One of the best experts on this subject based on the ideXlab platform.
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Interference, sensitivity and capacity analysis for measurement-based Wireless Access spectrum sharing
IEEE Transactions on Vehicular Technology, 1994Co-Authors: V.k. Varma, H.w. Arnold, D. Devasirvatham, A. Ranade, L.g. SutliffAbstract:In this paper, interference caused by multiple uncoordinated low-power Wireless Access system transmitters to fixed point-to-point microwave receivers is analyzed. The analysis shows that the density of Wireless Access system users that can share spectrum with point-to-point microwave systems depends critically on the propagation relation, the threshold of detecting energy from point-to-point transmitters, and the allowable interference into point-to-point receivers. We also show that, for reasonable assumptions of point-to-point link, Wireless Access system, and propagation parameters, a Wireless Access system employing measurement-based interference avoidance must detect energy of point-to-point transmissions far below the thermal noise floor of the Wireless Access system receivers. Meeting this requirement could increase the complexity of Wireless Access systems. This work is targeted towards understanding the implications for local exchange networks of Wireless system alternatives that could provide Access to those networks. >
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Interference, sensitivity and capacity calculations for measurement-based Wireless Access spectrum sharing
IEEE 43rd Vehicular Technology Conference, 1Co-Authors: V.k. Varma, H.w. Arnold, D. Devasirvatham, A. Ranade, L.g. SutliffAbstract:Interference caused by multiple uncoordinated low-power Wireless Access system transmitters to fixed point-to-point microwave receivers is analyzed. The analysis shows that the density of Wireless Access system users that can share spectrum with a point-to-point microwave system depends critically on the propagation relation, the threshold of detecting energy from point-to-point transmitters, and the allowable interference into point-to-point receivers. It is found that for reasonable assumptions of point-to-point link, Wireless Access system, and propagation parameters, a Wireless Access system employing measurement-based interference avoidance must detect energy of point-to-point transmissions far below the thermal noise floor of the Wireless Access system receivers which would increase their complexity. The implications to local exchange networks of Wireless system alternatives that could provide Access to those networks are addressed.
