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

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