The multilevel voltage source converters typically synthesize the staircase voltage wave from several levels of dc voltage sources. This paper presents a PWM modulation and hybrid modulation using cascaded topology which allows one to achieve high-quality output voltages and input currents and also outstanding availability due to their intrinsic component redundancy. The simulation results reve...

In this paper comparative study of proposed hybrid multilevel inverter (HMI) operating in modified pulse width modulation (PWM) mode with cascaded H-bridge multilevel inverter (CHMI) is done. Two types of HMIs are proposed with same configuration. To control the two HMIs, modified PWM techniques are derived from sinusoidal pulse width modulation (SPWM) to reduce the switching losses in the inve...

-An unequal error protection (UEP) optimization strategy is presented for binary regular LDPC coded modulation with high order constellation, such as MQAM. In contrast to conventional mapping method, this approach gives a considerable performance improvement with slight complexity increase. Furthermore, we extend this UEP method to Hybrid ARQ (HARQ) transmission with variable retransmission len...

The paper presents a process for assigning modulation and code rate in DS-CDMA for downlink throughput maximization. The system employed consists of a turbo encoder with PSK and QAM modulation with adaptation for slow-fading channels. The performance of the adaptation process is examined for 2-state, 4-state and 6-state sets of transmit parameters. The performance of the optimization process is...

transfer matrix method (tmm) has been applied to analyze characteristics of semiconductor laser optical amplifiers. the input signal is sinusoidal modulating wave and we do not assume the modulating bias signal as well. we have shown that the distoration arises from gain modulation at low modulation frequencies, but in microwave modulation frequencies, the gain takes an average value and the re...

In this work, we present the design, fabrication, and characterization of a surface-normal plasmonic modulator using sub-wavelength metal grating. The device consists of a 1.77 μm efficiently poled electro-optic polymer film, which is sandwiched between a plasmonic grating and an indium–tin oxide film. A strong Fano resonance with a sharp plasmonic bandgap at 1522 nm wavelength was observed and...

In this work, photovoltachromic cells (PVCCs) are fabricated using a solvent-free polyethylene glycol (PEG)-titanium hybrid polymer electrolyte. With appropriate addition of 1,2-dimethyl-3-propylimidazolium iodide in the electrolyte, the range of tunable colored-state transmittance of the PVCC is enlarged due to an improved fill factor. A transmittance modulation larger than 40% can be maintain...

An automatic repeat request (ARQ) scheme using rate compatible trellis coded modulation, pilot symbol aided channel estimation, soft output packet combining, and a retransmission request strategy supporting a variable quality of service within a packet is proposed. Simulation results show that this type II hybrid ARQ has about 3–5 dB SNR gain over its type I ARQ counterpart. Keywords— Hybrid AR...