3,572 research outputs found
Drop cost and wavelength optimal two-period grooming with ratio 4
We study grooming for two-period optical networks, a variation of the traffic
grooming problem for WDM ring networks introduced by Colbourn, Quattrocchi, and
Syrotiuk. In the two-period grooming problem, during the first period of time,
there is all-to-all uniform traffic among nodes, each request using
of the bandwidth; and during the second period, there is all-to-all uniform
traffic only among a subset of nodes, each request now being allowed to
use of the bandwidth, where . We determine the minimum drop cost
(minimum number of ADMs) for any and C=4 and . To do
this, we use tools of graph decompositions. Indeed the two-period grooming
problem corresponds to minimizing the total number of vertices in a partition
of the edges of the complete graph into subgraphs, where each subgraph
has at most edges and where furthermore it contains at most edges of
the complete graph on specified vertices. Subject to the condition that the
two-period grooming has the least drop cost, the minimum number of wavelengths
required is also determined in each case
A survey on OFDM-based elastic core optical networking
Orthogonal frequency-division multiplexing (OFDM) is a modulation technology that has been widely adopted in many new and emerging broadband wireless and wireline communication systems. Due to its capability to transmit a high-speed data stream using multiple spectral-overlapped lower-speed subcarriers, OFDM technology offers superior advantages of high spectrum efficiency, robustness against inter-carrier and inter-symbol interference, adaptability to server channel conditions, etc. In recent years, there have been intensive studies on optical OFDM (O-OFDM) transmission technologies, and it is considered a promising technology for future ultra-high-speed optical transmission. Based on O-OFDM technology, a novel elastic optical network architecture with immense flexibility and scalability in spectrum allocation and data rate accommodation could be built to support diverse services and the rapid growth of Internet traffic in the future. In this paper, we present a comprehensive survey on OFDM-based elastic optical network technologies, including basic principles of OFDM, O-OFDM technologies, the architectures of OFDM-based elastic core optical networks, and related key enabling technologies. The main advantages and issues of OFDM-based elastic core optical networks that are under research are also discussed
Energy-Efficient Design of Wavelength-Routing Networks
We discuss the power-aware Logical Topology Design problem in wavelength routing net- works, and analyze the economical impacts of power-efficiency. Results show that energy-optimized logical topologies can bring significant economical saving
A Simple Flood Forecasting Scheme Using Wireless Sensor Networks
This paper presents a forecasting model designed using WSNs (Wireless Sensor
Networks) to predict flood in rivers using simple and fast calculations to
provide real-time results and save the lives of people who may be affected by
the flood. Our prediction model uses multiple variable robust linear regression
which is easy to understand and simple and cost effective in implementation, is
speed efficient, but has low resource utilization and yet provides real time
predictions with reliable accuracy, thus having features which are desirable in
any real world algorithm. Our prediction model is independent of the number of
parameters, i.e. any number of parameters may be added or removed based on the
on-site requirements. When the water level rises, we represent it using a
polynomial whose nature is used to determine if the water level may exceed the
flood line in the near future. We compare our work with a contemporary
algorithm to demonstrate our improvements over it. Then we present our
simulation results for the predicted water level compared to the actual water
level.Comment: 16 pages, 4 figures, published in International Journal Of Ad-Hoc,
Sensor And Ubiquitous Computing, February 2012; V. seal et al, 'A Simple
Flood Forecasting Scheme Using Wireless Sensor Networks', IJASUC, Feb.201
Online traffic grooming using timing information in WDM–TDM networks
AbstractIn this paper, the effect of holding time awareness on the process of time slot assignment in WDM–TDM is considered. Use has been made of Markov model in order to predict the wavelength congestion. A routing algorithm is developed based on the Markov modeling. The results are compared with existing algorithms—ASP, WSP and OTGA. Validation results have shown that the performance of the system is significantly improved in terms of bandwidth blocking ratio, network utilization and fairness
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