Arun Agarwal

More than one order enhancement in peak detectivity (D*) for quantum dot infrared photodetectors implanted with low energy light ions (H−)

In(Ga)As/GaAs-based quantum dot infrared photodetectors (QDIPs) have emerged as one of the most suitable devices for infrared detection. However, quantum dot devices suffer from lower efficiencies due to a low fill-factor (∼20%–25%) of dots. Here, we report a post-growth technique for improving the QDIP performance using low energy light ion (H−) implantation. At high bias, there is evidence of suppression in the field-assisted tunneling component of the dark current. Enhancement in peak detectivity (D*), a measure of the signal-to-noise ratio, by more than one order, from ∼109 to 2.44 × 1010 cm Hz1/2/W was obtained from the implanted devices.

Performance prediction of OFDM based Digital Audio Broadcasting system using channel protection mechanisms

Radio broadcasting technology in this era of compact disc is expected to deliver high quality audio programmes in mobile environment. The Eureka-147 Digital Audio Broadcasting (DAB) system is a new digital radio technology for broadcasting radio stations that provides high-quality audio and data services to both fixed and mobile receivers and employs coded OFDM technology. This paper presents the bit error rate (BER) performance analysis of DAB system with different channel protection mechanisms in AWGN, Rayleigh, and Rice fading channels. The result shows that addition of protection level technique improves the system performance in mobile environment.

Performance Analysis of OFDM Based DAB Systems Using Concatenated Coding Technique

Radio broadcasting technology in this era of compact disc is expected to deliver high quality audio programmes in mobile environment. The Eureka-147 Digital Audio Broadcasting (DAB) system with coded OFDM technology accomplish this demand by making receivers highly robust against effects of multipath fading environment. In this paper, we have analyzed the performance of DAB system conforming to the parameters established by the ETSI (EN 300 401) using time and frequency interleaving, concatenated Bose-Chaudhuri-Hocquenghem coding and convolutional coding method in different transmission channels. The results show that concatenated channel coding improves the system performance compared to convolutional coding.

Performance Prediction of Eureka-147 DAB System Using Interleaving and Different Coding Rates

Radio broadcasting technology has evolved rapidly over the last few years due to ever increasing demands for as high quality sound services with ancillary data transmission in mobile environment. The Eureka-147 Digital Audio Broadcasting (DAB) system with coded OFDM technology accomplish this demand by making receivers highly robust against effects of multipath fading environment. In this paper, we have analyzed the performance of DAB system conforming to the parameters established by the ETSI (EN 300 401) using frequency interleaving and different coding rates in different transmission channels. The results show that interleaving is essential for the forward error correction to work properly and an increased coding rate makes the system more flexible without increase in the receiver complexity.

A technological analysis and survey on peak-to-average power reduction (PAPR) in MIMO-OFDM wireless system

With the constant demand of high spectral efficiency and high transmission speed for audio, video and internet application, MIMO-OFDM has become the most promising technology for present and future wireless communication. However, the main drawback of MIMO-OFDM system is high peak-to-average power ratio (PAPR) for large subcarrier which creates many problems in practical applications. Many methods are proposed to overcome the high PAPR problem like clipping, coding, phase rotation, signal scrambling etc. In this paper we present a brief analysis of different methods to reduce the high PAPR, such as selected mapping (SLM), partial transmit sequence (PTS), space frequency block code (SFBC) MIMO-OFDM and SFBC MIMO-OFDM with cooperative PTS.

Performance prediction of OFDM based DAB system using block coding techniques

Radio broadcasting technology has evolved rapidly over the last few years due to ever increasing demands for as high quality sound services with ancillary data transmission in mobile environment. The Eureka-147 Digital Audio Broadcasting (DAB) system accomplish this by use of coded OFDM technology that makes the receivers highly robust against the channel multipath effects. This paper presents the performance analysis of Eureka-147 DAB system conforming to the parameters established by the ETSI (EN 300 401) using frequency interleaving and Forward Error Correction (FEC) with block coding techniques in different transmission channels. The result shows that addition of block coding techniques improves the system performance in mobile environment.

Design and performance analysis of MIMO-OFDM system using different antenna configurations

The key challenge faced by future wireless communications systems is to provide high-data-rate wireless access at high quality of service (QOS). Multiple-input multiple-output (MIMO) wireless technology seems to meet these demands by offering increased spectral efficiency through spatial multiplexing gain, and improved link reliability due to antenna diversity gain. OFDM may be combined with antenna arrays at the transmitter and receiver to increase bandwidth efficiency and robustness using multipath signal propagation, resulting in a MIMO-OFDM configuration. The forward error correction (FEC) along with powerful interleaving algorithms plays an important role in the improvement of the performance of the MIMO-OFDM systems. In this paper we have designed a simple MIMO OFDM system with convolutional coding with code rate 1/2 and analysed the performance of the system using different antenna configuration in AWGN channel. It was concluded higher antenna configuration give best performance.

Performance improvement of induction motor by Selective Harmonic Elimination (SHE) using Newton Raphson (N-R) method

The paper presents an induction motor model with improvised performance by unified approach for selective Harmonic Elimination (SHE) of 3-Phase Voltage Source Inverter (VSI). Due to switching in inverters harmonics are present, the performance of inverter can be improved by reducing the harmonics. At this stage of time where everyone focus on increasing the level of inverter, lose their attention towards harmonic reduction. AS we know several modulation methods have been implemented to multilevel inverters. The modulation methods with higher switching frequency reduce filter size but increases switching losses. The Step modulation method operates with low switching frequency has less switching losses but the required filter size is large. To reduce the filter size the number of levels of the inverter has to be increased but it increases the cost of the system. This paper presents a novel modulation method where additional notches are introduced in the multi-level output voltage. The projected work investigates the Selective Harmonics Elimination (SHE) to eliminate harmonics produced by Pulse Width Modulation (PWM) [1] inverter. The model presented here eliminate the even order harmonics due to the symmetry of the wave, 3rd and multiple of 3rd order harmonics are eliminated due to fact that the harmonics wave of all 3 phases are in space phase, but differ in time phase by 120 degree, along with this 5th and 7th harmonics are eradicated by using SHE technique. The proposed modulation method is verified through MATLAB Simulink simulation.

Receiver synchronization for Digital Audio Broadcasting system based on Phase reference symbol

The Eureka-147 Digital Audio Broadcasting (DAB) system is a new digital radio technology for broadcasting radio stations that provides high-quality audio and data services to both fixed and mobile receivers and employs coded orthogonal frequency division multiplexing (COFDM) technology. In this paper, we present the efficient synchronization method based on Phase reference symbol (PRS) for the DAB signal at the receiver. Since DAB uses OFDM digital transmission technique, the synchronization block plays an important role in determining bit error rate (BER) performance of DAB system in different channels. The result shows that the synchronization method proposed locates precisely each DAB frame even at low signal to noise ratio (SNR), so that the demodulation can be performed frame by frame, symbol by symbol.

BER Performance Analysis of Image Transmission Using OFDM Technique in Different Channel Conditions Using Various Modulation Techniques

It can be clearly seen in the modern world of digital era that we depend a lot on mobile/smartphones which in return depends on data/information to proof its worthy. To meet this increased demand of data rate, new technology is needed as for old technology like GPRS and EDGE which is beyond their capacity. So orthogonal frequency division multiplexing (OFDM) takes this place as it increases the data rate in the same bandwidth, as it is also fixed. In this paper, we present a comparison between data handling using different modulations, which in turn can be assumed for bit error rate (BER) and signal-to-noise ratio (SNR) curve, of non-OFDM and OFDM channel under different fading environments.