IMPLEMENTATION OF OFDM MODULATOR AND DEMODULATOR FOR FPGA BASED APPLICATIONS

The new mobile technologies trying to give broadband over wireless channel allowing the user to have bandwidth connectivity even inside moving vehicle. The metropolitan broadband wireless networks require a non-line-of-sight (NLOS) capability, and the scheme Orthogonal Frequency Division Multiplex (OFDM) becomes essential to overcome the effects of multipath fading. Orthogonal Frequency Division Multiplexing (OFDM) has become very popular, allowing high speed wireless communications. OFDM could be considered either a modulation or multiplexing technique and its hierarchy corresponds to the physical and medium access layer. A basic OFDM modulator system consists of a PSK modulator, a serial to parallel, and an IFFT module. The iterative nature of the IFFT and its computational order makes OFDM ideal for a dedicated architecture outside or parallel to the main processor. The VHDL implementation allows the design to be extended for either FPGA or ASIC implementation, which suits more for the Software Defined Radio (SDR) design methodology. In this project the OFDM modulator and demodulator will be implemented with full digital techniques. VHDL will be used for RTL description and FPGA synthesis tools will be used for performance analysis of the proposed core. The major blocks are Interleaving/Mapping circuit, 8 point IFFT, 8 point FFT, and arithmetic blocks.