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;

A two-count ry, twōrm model has been developed to study equilibrium lobbying posit ions in intra-industry trade under cost uncertainty. A ̄rm chooses either a protect ionist posit ion or a free-t rader posit ion. The model predicts that taking the free-t rader (protect ionist) lobbying posit ion is an e± cient (ine± cient) ̄rm's dominant strategy. In addit ion, for any lobbying posit ion taken ...

We designed a VLSI chip of FFT multiplier based on simple Cooly Tukey FFT using a floating-point representation with optimal data length based on an experimental error analysis. The VLSI implementation using HITACHI CMOS 0.18μm technology can perform multiplication of 2 to 2 digit hexadecimal numbers 19.7 to 34.3 times (25.7 times in average) faster than software FFT multiplier at an area cost ...

In this work, an FFT architecture supporting variable FFT sizes, 128∼2048/1536, is proposed. This implementation is a combination of a 2 point Common Factor FFT and a 3 point DFT. Various FFT output pruning techniques for this architecture are discussed in terms of memory and control logic overhead. It is shown that the used Prime Factor FFT as an FFT in the 1536 point FFT is able to increase t...

This paper introduces a kind of FFT algorithm design and realization based on the Xilinx IP core . On the analysis of FFT algorithm, Rely on Xilinx Spartan -3A DSP FPGA series as platform, by calling FFT IP core, validating the feasibility and reliability in FFT algorithm medium or lower end FPGA. Keywords-FFT algorithm module, Xilinx IP core, Spartan 3A DSP, Fixed-point compression

Beamforming methods using antenna arrays have been used to suppress co-channel interferences in OFDM systems. These methods are grouped into two general classes of pre-FFT and post-FFT schemes. Post-FFT schemes normally exhibit better performance than their pre-FFT counterparts. However, in pilot-assisted OFDM systems the performance of post-FFT schemes drastically degrades due to subcarrier cl...

The numerical calculation of the Rayleigh-Sommerfeld diffraction integral is investigated. The implementation of a fast-Fourier-transform (FFT) based direct integration (FFT-DI) method is presented, and Simpson's rule is used to improve the calculation accuracy. The sampling interval, the size of the computation window, and their influence on numerical accuracy and on computational complexity a...