摘要
The fourth-generation(4G)and fifth-generation(5G)wireless communication systems use the orthogonal frequency division multiplexing(OFDM)modulation techniques and subcarrier allocations.The OFDM modulator and demodulator have inverse fast Fourier transform(IFFT)and fast Fourier transform(FFT)respectively.The biggest challenge in IFFT/FFT processor is the computation of imaginary and real values.CORDIC has been proved one of the best rotation algorithms for logarithmic,trigonometric,and complex calculations.The proposed work focuses on the OFDM transceiver hardware chip implementation,in which 8-point to 1024-point IFFT and FFT are used to compute the operations in transmitter and receiver respectively.The coordinate rotation digital computer(CORDIC)algorithm has read-only memory(ROM)-based architecture to store FFT twiddle factors and their angle generators.The address generation unit is required to fetch the data and write the results into the memory in the appropriate sequence.CORDIC provides low memory,delay,and optimized hardware on the field-programmable gate array(FPGA)in comparison to normal FFT architecture for the OFDM system.The comparative performance of the FFT and CORDICFFT based OFDM transceiver chip is estimated using FPGA parameters:slices,flip-flops,lookup table(LUTs),frequency,power,and delay.The design is developed using integrated synthesis environment(ISE)Xilinx version 14.7 software,synthesized using very-high-speed integrated circuit hardware description language(VHDL),and tested on Virtex-5 FPGA.
