Wireless OFDM signals typically have a cyclicprefixed guard interval. The FFT timing synchronisation at the receiver is traditionally based on the peak point of the correlation output between the guard interval and its corresponding duplicate at the OFDM symbol’s tail. This approach does not in general find the optimum timing position for the FFT when the channel contains more than one path. Th...

In this paper, we proposed an variable length FFT processor architecture which could be used in multi-mode and multi-standard OFDM communication system. Based on radix-2 single-path delay feedback architecture, FFT is implemented with the aid of LUT and control logic. The expected architecture would complete FFT ranging 2048/1024/512point. Keywords-FFT; Radix-2 FFT; variable length FFT;

The 60 GHz band is of much interest since this is the band in which a massive amount of spectral space (5 GHz) has been allocated unlicensed worldwide for dense wireless local communications. Orthogonal frequency division multiplexing (OFDM) has gained much popularity in the field of wireless communication because of its ability to transfer the data at higher rate, high bandwidth efficiency and...

Alomouti’s space-time coding scheme for Multi-Input Multi-Output (MIMO) system has drawn much attention in 4G wireless technologies. Orthogonal frequency division multiplexing (OFDM) is a popular method for high data rate wireless transmission. OFDM may be combined with antenna arrays at the transmitter and receiver to increase the diversity gain and enhance the system capacity on time variant ...

⎯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 present scenario every process should be efficient and simple. Fast Fourier Transform (FFT) is an efficient algorithm to compute the N point DFT. The main focus of this paper is to design FFT using ALU which is used in receiver blocks of OFDM system. It has greater applications in signal and image processing, communication and instrumentation. But the design of FFT requires large number of a...

In this paper, the performance of Dicrete Wavelet Transform (DWT) based Multi-user MIMO-OFDM is compared with the performance of FFT based MIMO-OFDM system. Wavelet based OFDM has lot of advantages compared to the FFT based OFDM. There is no need for cyclic prefix, flexibility and optimal resolution. Wavelets existed suitably in almost all the arenas of wireless communication schemes with OFDM ...

We propose a four-dimensional (4D) coded multiband-OFDM scheme suitable for beyond 1.4 Tb/s serial optical transport. The proposed scheme organizes the N-dimensional (ND) signal constellation points in the form of signal matrix; employs 2D-inverse FFT and 2D-FFT to perform modulation and demodulation, respectively; and exploits both orthogonal polarizations. This scheme can fully exploit advant...

The Orthogonal Frequency Division Multiplexing (OFDM) has widely been used in broadband wireless communication due to its ability to efficiently utilize the spectrum with multicarrier communication. In this paper BER expression for π/4 DQPSK modulation has been derived from FrFT based OFDM system in the presence of carrier frequency offset (CFO) under frequency selective Rayleigh fading channel...

In recent years, as a result of advancing VLSI technology, OFDM has received a great deal of attention and been adopted in many new generation wideband data communication systems such as IEEE 802.11a, HiPerLAN/2, digital audio/video broadcasting (DAB/DVB-T) and asymmetric digital subscriber line (ADSL), very high speed digital subscriber line (VDSL) in wireless and wired communications, respect...