Search results for "NETWORKING"
showing 10 items of 1776 documents
Decoupled Downlink-Uplink Coverage Analysis with Interference Management for Enriched Heterogeneous Cellular Networks
2016
Heterogeneous cellular networks (HetCNets) offer a promising solution to cope with the current cellular coverage crunch. Due to the large transmit power disparity, while following maximum power received (MPR) association scheme, a larger number of users are associated with macro-cell BS (MBS) than small-cell BSs (SBSs). Therefore, an imbalance load arrangement takes place across the HetCNets. Hence, using cell range expansion-based cell association, we can balance the load across the congested MBS. However, using MPR association scheme, users’ offloading leads to two challenges: 1) macro-cell interference , in which the MBS interferes with the offloaded users, and 2) coupled downlink-uplink…
Analysis of load balancing and interference management in heterogeneous cellular networks
2017
To meet the current cellular capacity demands, proactive offloading is required in heterogeneous cellular networks (HetCNets) comprising of different tiers of base stations (BSs), e.g., small-cell BSs (sBSs) and conventional macro-cell BSs (mBSs). Each tier differs from the others in terms of BS transmit power, spatial density, and association bias. Consequently, the coverage range of each tier BSs is also different from others. Due to low transmit power, a fewer number of users are associated to an sBS as compared with mBS. Thus, inefficient utilization of small-cell resources occurs. To balance the load across the network, it is necessary to push users to the underloaded small cells from …
Cooperative RTS/CTS MAC with relay selection in distributed wireless networks
2009
This paper proposes a cooperative multiple access protocol based on the Distributed Coordination Function (DCF) Request-To-Send/Clear-To-Send (RTS/CTS) scheme for distributed wireless networks. It answers three key questions concerning cooperation from the network perspective, namely when to cooperate, whom to cooperate with and how to protect cooperative transmissions. According to our protocol, the cooperation is initiated only if the direct transmission fails. An optimal relay node is selected in a distributed manner according to instantaneous relay channel conditions without prior information or extra signaling among relay candidates in the network. An additional three-way handshake is …
Revisit of RTS/CTS Exchange in High-Speed IEEE 802.11 Networks
2005
IEEE 802.11 medium access control (MAC), called distributed coordination function (DCF), provides two different access modes, namely, 2-way (basic access) and 4-way (RTS/CTS) handshaking. The 4-way handshaking has been introduced in order to combat the hidden terminal phenomenon. It has been also proved that such a mechanism can be beneficial even in the absence of hidden terminals, because of the collision time reduction. We analyze the effectiveness of the RTS/CTS access mode, in current 802.11b and 802.11a networks. Since the rates employed for control frame transmissions can be much lower than the rate employed for data frames, the assumption on the basis of the 4-way handshaking introd…
Advanced Stochastic Petri Net Modeling with the Mercury Scripting Language
2017
Formal models are widely used in performance and dependability studies of computational systems. Graphical modeling tools allow users to compose such models with ease, but they complicate the creation of models with a dynamic/complex structure, the hierarchical arrangement of different models, and the automatic execution of models with different parameter configurations. To overcome this problem, we created a scripting language for the Mercury tool that supports the combination of different modeling approaches (e.g., Stochastic Petri Nets and Reliability Block Diagrams) in a single project. In this paper, we focus on the extensions developed to improve the capabilities of Generalized Stocha…
Dynamical efficiency of collisionless magnetized shocks in relativistic jets
2010
The so-called internal shock model aims to explain the light-curves and spectra produced by non-thermal processes originated in the flow of blazars and gamma-ray bursts. A long standing question is whether the tenuous collisionless shocks, driven inside a relativistic flow, are efficient enough to explain the amount of energy observed as compared with the expected kinetic power of the outflow. In this work we study the dynamic efficiency of conversion of kinetic-to- thermal/magnetic energy of internal shocks in relativistic magnetized outflows. We find that the collision between shells with a non-zero relative velocity can yield either two oppositely moving shocks (in the frame where the co…
The Y(3940), Z(3930) and the X(4160) as dynamically generated resonances from the vector-vector interaction
2010
We study the vector-vector interaction within the framework of the hidden gauge formalism for the sector with quantum numbers charm C=0 and strangeness S=0 in the region around 4000 MeV. We get five poles, three of which could be identified with the Y(3940), Z(3930) and X(4160). These poles appear with quantum numbers I=0 and $J^{PC}=0^{++},2^{++}$ and $2^{++}$, respectively, and can be considered as hadronic molecules made of $D^*\bar{D}^*$, $D_s^*\bar{D}^*_s$.
Scalar, axial-vector, and tensor resonances from the rho D-*, omega D-* interaction in the hidden gauge formalism
2009
13 pages, 15 figures.-- PACS nrs.: 13.75.Lb, 12.40.Vv, 12.40.Yx, 14.40.Cs.-- ArXiv pre-print available at: http://arxiv.org/abs/0903.3823
Measurement of vertical bar V-cs vertical bar using W decays at LEP2
1998
Decays of W± bosons, produced at LEP2, have been used to measure the |Vcs| element of the Cabibbo-Kobayashi-Maskawa matrix. Values for |Vcs| were extracted both from the measured hadronic branching ratio of W± decays and by tagging the flavour of hadronic jets produced in W± decays. Applying the two methods to the data collected during 1996 at energies of 161 and 172 GeV, DELPHI obtains |Vcs|=0.91+0.15−0.14(stat)±0.05(syst).
A circularly polarized wideband high gain patch antenna for wireless power transfer
2018
This article deals with a microstrip patch antenna working at 868 MHz, suitable for the radio frequency wireless power transfer and energy harvesting applications. The proposed monolithic antenna is compact, lightweight and it is printed on a thick substrate in order to maximize the total gain in the broadside direction. The antenna radiates at 868 MHz with a fractional impedance bandwidth of 5% and it shows a gain of 4.14 dB.