Search results for "Computer Science::Networking and Internet Architecture"
showing 10 items of 137 documents
Spectral Slicing of a Supercontinuum Source for WDM/DS-OCDMA Application
2008
WDM and optical CDMA are leading contenders to easily upgrade access network performances in terms of multiple access technique. Both methods can be used at once, using a single multiwavelength optical source. We show, numerically and experimentally, that spectral slicing of a 10-GHz pulse train broadened to a supercontinuum yields pulses suitable for use in a direct sequence optical CDMA system. Simulations with optical CDMA encoders and decoders based on superstructured fiber Bragg gratings indicate good performance can be expected.
Joint Power Allocation and Link Selection for Multi-Carrier Buffer Aided Relay Network
2019
In this paper, we present a joint power allocation and adaptive link selection protocol for an orthogonal frequency division multiplexing (OFDM)-based network consists of one source node i.e., base station (BS), one destination node i.e., (MU) and a buffer aided decode and forward (DF) relay node. Our objective is to maximize the average throughput of the system via power loading over different subcarriers at source and relay nodes. A separate power budget is assumed at each transmitting node to make the system more practical. In order to form our solution more tractable, a decomposition framework is implemented to solve the mixed integer optimization problem. Further, less complex suboptim…
Distributed Resource Allocation for Energy Efficiency in OFDMA Multicell Networks with Wireless Power Transfer
2019
In this paper, an energy-efficient resource allocation problem is investigated for the wireless power transfer (WPT)-enabled OFDMA multicell networks. In the considered system, multiple base stations (BSs) with a large number of antennas are responsible to provide WPT in the downlink, and the users can recycle and utilize the received energy for uplink data transmission. The role of BS is to execute WPT; thus, there are no data transmissions in the downlink. A time-division protocol is considered to divide the time of downlink WPT and uplink wireless information transfer into separate time slots. With the objective to improve the energy efficiency, we propose the time, subcarrier, and power…
Energy Efficient Sink Placement in Wireless Sensor Networks by Brain Storm Optimization Algorithm
2018
Wireless sensor networks represent one of the most promising technologies whose use has significantly increased in the past years. They are used in various applications such as health care monitoring, surveillance and monitoring in agriculture, industrial monitoring, habitat and underwater monitoring, etc. Deployment of the wireless sensor networks introduces number of hard optimization problems. Placement of the elements such as sensors, gateways, sinks and base stations, depend on different conditions and constraints such as signal propagation, distance, energy preservation, reliability. In this paper, we propose a method based on brain storm optimization algorithm for placing multiple si…
"Table 16" of "Measurement of the inclusive W+- and Z/gamma cross sections in the electron and muon decay channels in pp collisions at sqrt(s) = 7 Te…
2014
Factors to correct the measured cross-sections for different treatments of photon final-state radiation (QED FSR) to: - dressed leptons, recombined with FSR photons in a cone of DeltaR < 0.1 and - bare leptons, defined after FSR. These correction factors are found to be (pseudo)-rapidity independent.
Letter Throughput and Delay Analysis of the Ideal Window
1999
We consider the problem of random access communications over a time slotted channel with feedback of infinitely multiplicity at the beginning of each collision resolution interval (CRI), i.e., users know via instantaneous feedback the number of users involved in that collision. Once this is known, the resolution algorithm (CRA) operates with binary (successful / non successful, s/ns) feedback. The analysis of this simple full feedback sensing window random access algorithm, named ideal window stabilized ALOHA, (IWSA), algorithm, provides a throughput of 0.5052 packets/slot, Its delay is also analyzed and compared with similar algorithms.
The UWB-OFDM Channel Analysis in Frequency
2009
In this paper, the ultra-wideband channel with orthogonal frequency division multiplexing (UWB-OFDM) is analyzed in the frequency domain. For UWB-OFDM channels with log-normal fading in the time domain, we show that the amplitude of each subcarrier can be approximated by a Nakagami-m random variable, where the fading parameter, the mean power and the correlation coefficient are expressed in terms of the following parameters: time arrival of the clusters, inter-arrival time of rays inside clusters, and power decay constants of rays and clusters.
Dispersion relation formalism for virtual Compton scattering of the proton
2001
We present in detail a dispersion relation formalism for virtual Compton scattering (VCS) off the proton from threshold into the $\Delta(1232)$-resonance region. Such a formalism can be used as a tool to extract the generalized polarizabilities of the proton from both unpolarized and polarized VCS observables over a larger energy range. We present calculations for existing and forthcoming VCS experiments and demonstrate that the VCS observables in the energy region between pion production threshold and the $\Delta(1232)$-resonance show an enhanced sensitivity to the generalized polarizabilities.
Anomalous Spreading of Power-Law Quantum Wave Packets
1999
We introduce power-law tail quantum wave packets. We show that they can be seen as eigenfunctions of a Hamiltonian with a physical potential. We prove that the free evolution of these packets presents an asymptotic decay of the maximum of the wave packets which is anomalous for an interval of the characterizing power-law exponent. We also prove that the number of finite moments of the wave packets is a conserved quantity during the evolution of the wave packet in the free space.
The Wigner Distribution of Sum-of-Cissoids and Sum-of-Chirps Processes for the Modelling of Stationary and Non-Stationary Mobile Channels
2016
This paper concerns the time-frequency analysis of stationary and non-stationary multipath flat fading channels. For the modelling of stationary multipath fading channels, we use a sum-of-cisoids (SOCi) process, while the non-stationary channel is modelled by a sum-of-chirps (SOCh) process that captures the time-variant Doppler effect caused by speed variations of the mobile station. For the time-frequency analysis, we apply the concept of the Wigner distribution. Closed-form solutions are provided for the Wigner distribution of SOCi and SOCh processes. It is shown that the obtained Wigner distributions can be expressed by the sum of an auto-term representing the true Doppler power spectral…