In this paper, a new adaptive transmit diversity selection (ATDS) scheme is proposed for future wireless communication system to provide high spectral efficiency (SE) and good quality of service (QOS) .The ATDS scheme selects the space time block code (STBC) orthogonal frequency division multiplexing (OFDM) scheme for flat fading channel and it selects space frequency block code (SFBC) OFDM sch...

The designing of charge pump with high gain OpAmp is a challenging task for getting faithful response .Design of high performance phase locked loop require ,a design of high performance charge pump .We have designed a operational amplifier for reducing the error caused by high speed glitch in a transistor and mismatch currents . A separate Op-Amp has designed in 180 nm CMOS technology by CADENC...

In this paper, we describe the Orthogonal frequency division multiplexing (OFDM) is an established technique for wireless communication applications. Typical constraints faced during OFDM transmission are: a large peak-to-mean envelope power ratio, which can result in significant distortion when transmitted through a nonlinear device, such as a transmitter power

In this letter, we propose a combined scheme of minimum mean square error (MMSE) detection and successive interference cancellation (SIC) for multiuser space-time block coded orthogonal frequency division multiplexing (STBC-OFDM) systems. With the same complexity order, the proposed scheme provides significant bit error rate (BER) performance improvement over the linear MMSE multiuser detector....

Space-time block codes provide substantial diversity advantages for multiple transmit antenna systems at a low decoding complexity. In this study, we concatenate both space-time block and trellis codes with Turbo Convolutional (TC) coded Orthogonal Frequency Division Multiplexing (OFDM) for achieving a high coding gain. The associated performance and complexity of the coded OFDM schemes is comp...

Orthogonal frequency division multiplexing (OFDM) is regarded widely as the key underlying air interface technology for wireless systems such as WiMAX, 3GPP long-term evolution (LTE), and 3GPP2 ultra-mobile broadband (UMB). Due to the inherent nature of these technologies, OFDM signals have high peak-to-average power ratio (PAR) that adversely affects the efficiency of power amplifiers (PAs) us...

In this contribution, we give an overview of the sensitivity of a number of multicarrier systems to carrier and symbol synchronization errors. A comparison is made between orthogonal frequency-division multiplexing/multiple access (OFDM(A)) and two combinations of the orthogonal multicarrier (MC) transmission technique with the code-division multiple access technique (CDMA), i.e. multicarrier C...

57  Abstract— OFDM (Orthogonal Frequency Division Multiplexing) is spectrally efficient modulation technique used for higher data rate transmission. Basically OFDM system is very effective technique in its way ,but main disadvantage is Peak to Average Power Ratio. This Ratio Must be reduce to perfom efficient communication. Different technique can be used to reduce it. Here in this paper propo...

In Spectrally Efficient Frequency Division Multiplexing (SEFDM) systems the input data stream is divided into several adjacent subchannels where the distance of the subchannels is less than that of Orthogonal Frequency Division Multiplexing (OFDM) systems. Since the subcarriers are not orthogonal in SEFDM systems, they lead to interference at the receiver side. In this paper, an iterative metho...

A fine timing and frequency synchronization algorithm is presented for an orthogonal frequency division multiplexing (OFDM) system used in China mobile multimedia broadcasting (CMMB). The presented algorithm could accomplish the timing and frequency offset estimation using the perfect relation of training symbols. The simulation and practice results show the new algorithm could give out fine ti...