The Experts below are selected from a list of 63 Experts worldwide ranked by ideXlab platform

Tetsuya Kawanishi - One of the best experts on this subject based on the ideXlab platform.

  • high capacity wireless backhaul Network using seamless convergence of radio over fiber and 90 ghz millimeter wave
    Journal of Lightwave Technology, 2014
    Co-Authors: Pham Tien Dat, Atsushi Kanno, Keizo Inagaki, Tetsuya Kawanishi
    Abstract:

    We propose and experimentally demonstrate a seamlessly converged radio-over-fiber (RoF) and millimeter-wave system at 90 GHz for high-speed wireless signal transmission. We successfully transmit and demodulate standard orthogonal frequency-division multiplexing-based wireless Local Access Network (WLAN) signals, long term evolution eNB conformance test models, and long term evolution advanced signals over the system. Satisfactory transmission performance over the converged RoF and a 5-m 90-GHz wireless link is achieved. The measured root-mean-square error vector magnitude is well under the requirement defined by the standards. We also investigate the dependence of the transmission performance on the fiber length due to the effect of fiber dispersion and estimate the achievable wireless transmission distance. The estimated transmission range of both the fiber length and wireless link are sufficiently long for practical applications, such as mobile backhaul/fronthaul, wireless Access Network for WLAN signals. Possible solutions and the estimated transmission range are also discussed to use millimeter-wave and RoF system convergence for uplink transmission. The obtained results confirm the potential to use the system in future high-speed, small-cell mobile Networks and in broadband wireless Access Networks.

Sibel F Salman - One of the best experts on this subject based on the ideXlab platform.

  • solving the capacitated Local Access Network design problem
    Informs Journal on Computing, 2008
    Co-Authors: Sibel F Salman, R. Ravi, John N Hooker
    Abstract:

    We propose an exact solution method for a routing and capacity installation problem in Networks. Given an input graph, the problem is to route traffic from a set of source nodes to a sink node and to install transmission facilities on the edges of the graph to accommodate the flow at minimum cost. We give a branch-and-bound algorithm that solves relaxations obtained by approximating the noncontinuous cost function by its lower convex envelope. The approximations are refined by branching on the flow ranges on selected edges. Our computational experiments indicate that this method is effective in solving moderate-size problems and provides very good candidate solutions early in the branch-and-bound tree.

  • approximation algorithms for a capacitated Network design problem
    Algorithmica, 2004
    Co-Authors: Refael Hassin, R. Ravi, Sibel F Salman
    Abstract:

    We study a capacitated Network design problem with applications in Local Access Network design. Given a Network, the problem is to route flow from several sources to a sink and to install capacity on the edges to support the flow at minimum cost. Capacity can be purchased only in multiples of a fixed quantity. All the flow from a source must be routed in a single path to the sink. This NP-hard problem generalizes the Steiner tree problem and also more effectively models the applications traditionally formulated as capacitated tree problems. We present an approximation algorithm with performance ratio (ρST + 2) where ρST is the performance ratio of any approximation algorithm for the minimum Steiner tree problem. When all sources have unit demand, the ratio improves to ρST + 1) and, in particular, to 2 when all nodes in the graph are sources.

Pham Tien Dat - One of the best experts on this subject based on the ideXlab platform.

  • high capacity wireless backhaul Network using seamless convergence of radio over fiber and 90 ghz millimeter wave
    Journal of Lightwave Technology, 2014
    Co-Authors: Pham Tien Dat, Atsushi Kanno, Keizo Inagaki, Tetsuya Kawanishi
    Abstract:

    We propose and experimentally demonstrate a seamlessly converged radio-over-fiber (RoF) and millimeter-wave system at 90 GHz for high-speed wireless signal transmission. We successfully transmit and demodulate standard orthogonal frequency-division multiplexing-based wireless Local Access Network (WLAN) signals, long term evolution eNB conformance test models, and long term evolution advanced signals over the system. Satisfactory transmission performance over the converged RoF and a 5-m 90-GHz wireless link is achieved. The measured root-mean-square error vector magnitude is well under the requirement defined by the standards. We also investigate the dependence of the transmission performance on the fiber length due to the effect of fiber dispersion and estimate the achievable wireless transmission distance. The estimated transmission range of both the fiber length and wireless link are sufficiently long for practical applications, such as mobile backhaul/fronthaul, wireless Access Network for WLAN signals. Possible solutions and the estimated transmission range are also discussed to use millimeter-wave and RoF system convergence for uplink transmission. The obtained results confirm the potential to use the system in future high-speed, small-cell mobile Networks and in broadband wireless Access Networks.

Peter Putz - One of the best experts on this subject based on the ideXlab platform.

  • A MIP-based approach to solve the Prize-Collecting Local Access Network Design Problem
    2013
    Co-Authors: Peter Putz
    Abstract:

    This paper presents a new combinatorial optimization problem that can be used to model the deployment of broadband telecommunications systems in which optical fiber cables are installed between a central office and a number of end-customers. In this capacitated Network design problem the installation of optical fiber cables with sufficient capacity is required to carry the traffic from the central office to the end-customers at minimum cost. In the situation motivating this research the Network does not necessarily need to connect all customers (or at least not with the best available technology). Instead, some nodes are potential customers. The aim is to select the customers to be connected to the central server and to choose the cable capacities to establish these connections. The telecom company takes the strategic decision of fixing a percentage of customers that should be served, and aims for minimizing the total cost of the Network providing this minimum service. For that reason the underlying problem is called the Prize-Collecting Local Access Network Design problem (PC-LAN). We propose a branch-and-cut approach for solving small instances. For large instances of practical importance, our approach turns into a mixed integer programming (MIP) based heuristic procedur

Luis Gouveia - One of the best experts on this subject based on the ideXlab platform.

  • a node rooted flow based model for the Local Access Network expansion problem
    European Journal of Operational Research, 2010
    Co-Authors: Margarida Cortereal, Luis Gouveia
    Abstract:

    In this paper, we present a new formulation for the Local Access Network expansion problem. Previously, we have shown that this problem can be seen as an extension of the well-known Capacitated Minimum Spanning Tree Problem and have presented and tested two flow-based models. By including additional information on the definition of the variables, we propose a new flow-based model that permits us to use effectively variable eliminations tests as well as coefficient reduction on some of the constraints. We present computational results for instances with up to 500 nodes in order to show the advantages of the new model in comparison with the others.