⎯The IEEE 802.16d communication standard uses orthogonal frequency division multiplexing (OFDM). In the widely used OFDM systems, the fast Fourier transform (FFT) and inverse fast Fourier transform pairs are used to modulate and demodulate the data constellation on the sub-carriers. In this paper, a high level implementation of a high performance FFT for OFDM modulator and demodulator is presen...

In this paper, a method for CFO/RFO estimation based on proportional coefficients extraction in OFDM system is proposed, which may be applied to any pilot symbol pattern. Keywords—OFDM (Orthogonal Frequency Division Multiplexing), CFO (Carrier Frequency Offset, Redundancy Frequency Offset), proportional coefficient extraction.

Cooperative communication is a fourth generation novel scheme promising significant capacity and multiplexing gain in wireless communication. This paper derives the carrier to noise interference ratio (CNIR) and average bit error rate (BER) for orthogonal frequency division multiplexing (OFDM) based amplify and forward (AF) and decode and forward (DF) scheme over Nakagami fading channels. Numer...

In an Orthogonal Frequency Division Multiplexing (OFDM) systems, the Peak to Average power Ratio (PAR) is high. The clipping signal scheme is a useful and simple method to reduce the PAR. However, it introduces additional noise that degrades the systems performance. We propose an oversampling scheme to deal with the received signal in order to reduce the clipping noise by using finite impulse r...

Since an FFT-based speech encryption system retains a considerable residual intelligibility, such as talk spurts and the original intonation in the encrypted speech, this makes it easy for eavesdroppers to deduce the information contents from the encrypted speech. In this letter, we propose a new technique based on the combination of an orthogonal frequency division multiplexing (OFDM) scheme a...

To improve performance of orthogonal frequency division multiplexing (OFDM) for fading channels, linear dispersion coded OFDM (LDC-OFDM) was recently proposed to increase frequency and time diversity with high bandwith efficiency and performance. The performance of recently proposed LDC-OFDM was investigated through simulations. This paper analyzes the diversity aspects of LDCOFDM system, and s...

The fast development of modern communication techniques, the demand for reliable high data rate transmission is increased signification, which stimulate much interest in modulation technique. The QAM is one of the adaptive modulation techniques that are commonly used for wireless communications. Different order modulations allow sending more bit per symbol and thus achieving higher throughput o...

Orthogonal Frequency Division Multiplexing (OFDM) has grown to a popular communication technique for high speed communication in the last decade. OFDM is an important member of the multicarrier modulation (MC) techniques and it has been adopted as a standard for various high data rate wireless communication systems due to its spectral bandwidth efficiency, robustness to frequency selective fadi...

Increased data rates and reliability are the two key factors required to support emerging multimedia applications and new communications technologies. The two techniques used in high data rate transmission are orthogonal frequency division multiplexing (OFDM) and multiple-input multiple-output (MIMO) scheme. The OFDM is used to mitigate the problem of inter symbol interference (ISI) and provide...