1,850 research outputs found
Improved Predictive Power Control Algorithms to Increase CDMA System Capacity
In this paper capacity of CDMA system is evaluated using an improved algorithm of channel prediction-based power control in Rayleigh fading channel environments. One of the most serious problems which degrades the performance of power control algorithm is the effect of feedback delay. To overcome the effect of feedback delay, power control algorithm relies on channel prediction techniques, which utilize the correlation property of the past channel measurements. In CDMA power control, however, the correlation property of channel measurements is destroyed because the transmit power is continuously updated for each power control interval. In order to restore the correlation property of the channel, the past channel measurements are compensated for by the same factors that were given by power updating for each power control interval. The prediction algorithm in this paper is proposed using the least mean square (LMS) technique. The result shows that the capacity of CDMA systems increase significantly when the improved predictive algorithm is used. Numerical evaluation shows that CDMA capacity increases by more than 40 % for fixed step algorithm and more than 50 % for variable step algorithm when the proposed algorithm is employed.
Plasmon-assisted two-photon Rabi oscillations in a semiconductor quantum dot -- metal nanoparticle heterodimer
Tho-photon Rabi oscillations hold potential for quantum computing and quantum
information processing, because during a Rabi cycle a pair of entangled photons
may be created. We theoretically investigate the onset of this phenomenon in a
heterodimer comprising a semiconductor quantum dot strongly coupled to a metal
nanoparticle. Two-photon Rabi oscillations in this system occur due to a
coherent two-photon process involving the ground-to-biexciton transition in the
quantum dot. The presence of a metal nanoparticle nearby the quantum dot
results in a self-action of the quantum dot via the metal nanoparticle, because
the polatization state of the latter depends on the quantum state of the
former. The interparticle interaction gives rise to two principal effects: (i)
- enhancement of the external field amplitude and (ii) - renormalization of the
quantum dot's resonance frequencies and relaxation rates of the off-diagonal
density matrix elements, both depending on the populations of the quantum dot's
levels. Here, we focus on the first effect, which results in interesting new
features, in particular, in an increased number of Rabi cycles per pulse as
compared to an isolated quantum dot and subsequent growth of the number of
entangled photon pairs per pulse. We also discuss the destructive role of
radiative decay of the excitonic states on two-photon Rabi oscillations for
both an isolated quantum dot and a heterodimer.Comment: 11 pages, 19 figure
The effect of combined therapy using arthemisinin and red fruit oil towards the erythrocyte Mmlondyaldehide level in mice balb/c infected with Plasmodium berghei
Sekuen Asam Amino Anti White Spot Syndrome Virus (Wssv) pada Udang Windu (Penaeus Monodon)
This study aimed to determine the amino acid sequencehomology, functional domains, the model predictionof protein structure and characteristics of genesencoding anti WSSV in black tiger shrimp (Penaeusmonodon) originated from Indramayu District. Theresearch method was qualitative descriptive analysis bycomparing the results of PCR isolation of genes encodinganti WSSV with GenBank sequence data. The resultsshowed that the sequence gene encoding anti WSSV inblack tiger shrimp DNA originated Indramayu genesequences homologous with Penaeus monodon AV gene,complate cds (no. Accession DQ641258.1) and Penaeusmonodon PMAV (PmAV) mRNA, complete cds (no.Accession AY3202750.1). C -type lectin is a functionaldomain of the amino acid sequences of anti WSSVin black tiger shrimp. The structure of the proteinencoding anti WSSV (c -type lectin) is characterized bythe presence of a signal peptide, alpha helix clusters, betastrand and there are in three cells zones. C-type lectinindicated could help improved the resistance of blacktiger shrimp from Indramayu district against WSSVand the c -type lectin could be found in various typesof organisms to be developed as an immunostimulatorysubstance
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