3G Long Term Evolution, which aims for various mobile multimedia services provision by enhanced wireless performance, proposes the VoIP-based voice service through the PS domain. When delay and loss-sensitive VoIP traffic flows through the PS domain, more challenging technical difficulties are expected than in the existing 3G systems which provide the CS domain based voice service. Moreover, since 3G LTE, which adopts the OFDM as its physical layer, introduces Physical Resource Block (PRB) as the unit for the transmission resources, it becomes necessary to develop new types of resource management schemes. This paper proposes a MAC layer PRB scheduling algorithm for the efficient VoIP service in 3G LTE and shows the simulation results regarding its performance. The key idea of the algorithm consists of two parts; dynamic activation of a VoIP priority mode for the voice QoS satisfaction and adaptive adjustment of the VoIP priority mode duration in order to minimize the performance degradation induced by its priority mode application.
We consider the bandwidth packing problem arising from telecommunication networks. The problem is to determine the set of calls and an assignment of them to the paths in an arc-capacitated network to maximize profit. We propose an algorithm to solve the integer programming formulation of the problem. An efficient column generation technique to solve the linear programming relaxation is proposed, and a modified cover inequality is used to strengthen the IP formulation. The algorithm incorporates the column generation technique and the strong cutting plane approach into a branch-and-bound scheme. We test the proposed algorithm on some random problems. The results show that the algorithm can be used to solve the problems within reasonably small time limits.bandwidth packing, zero-one programming, polyhedral cuts, branch-and-cut
Incorporation
of quantum dots (QDs) into color filters (CFs) are
desired for less energy loss and wider viewing angle compared to a
conventional display. However, aggregation and vulnerability to heat,
moisture, and chemicals in the photo-patternable matrix are critical
issues of the QD-CFs with high QDs concentration. Herein, we fabricated
red (10 wt %) and green (20 wt %) QD-CFs using photolithography of
QD/siloxane ink containing secondary thiol monomer. Ligand-exchanged
QDs were chemically incorporated in methacrylate oligosiloxane resin.
QD/siloxane composite showed superior stability under harsh heat and
moisture (85 °C/5% RH and 85 °C/85% RH) conditions and chemicals
(EtOH, HCl, and NaOH) compared to conventional QD/PR (commercial negative
photoresist). QD-CFs (10 μm thick) effectively converted blue
light emitted from LED chip into red and green light, and the obtained
white PL through QD-CF showed wide color gamut, which was 108% relative
to NTSC. From these advantages, QD/siloxane composite will be beneficial
as color-conversion photoresists are to be used as color filters in
liquid crystal displays, micro light-emitting diodes, and organic
light-emitting diodes.
Substrates with high transmittance and high haze are desired for increasing the light outcoupling efficiency of organic light‐emitting diodes (OLEDs). However, most of the polymer films used as substrate have high transmittance and low haze. Herein, a facile route to fabricate a built‐in haze glass‐fabric reinforced siloxane hybrid (GFRH) film having high total transmittance (≈89%) and high haze (≈89%) is reported using the scattering effect induced by refractive index contrast between the glass fabric and the siloxane hybrid (hybrimer). The hybrimer exhibiting large refractive index contrast with the glass fabric is synthesized by removing the phenyl substituents. Besides its optical properties, the hazy GFRH films exhibit smooth surface (Rsq = 0.2 nm), low thermal expansion (13 ppm °C−1), high chemical stability, and dimensional stability. Owing to the outstanding properties of the GFRH film, OLED is successfully fabricated onto the film exhibiting 74% external quantum efficiency enhancement. The hazy GFRH's unique optical properties, excellent thermal stability, outstanding dimensional stability, and the ability to perform as a transparent electrode enable them as a wide ranging substrate for the flexible optoelectronic devices.
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