COMPONENT DESIGN OF CPM-OFDM BASED WAVEFORM FOR SDR

Abstract

Continuous Phase Modulation Orthogonal Frequency Division Multiplexing (CPM-OFDM) is a multi carrier modulation technique.. The main advantage of this transmission technique over ordinary OFDM technique is Zero Peak to Average Power ratio (PAPR). The objective of this project is to design and implement a baseband CPM-OFDM transmitter and receiver. Both transmitter and receiver are implemented on a single FPGA with a wire as a channel. The FPGA Board being used is Xilinx’s SPARTAN XC3S400. The designing language being used is Verilog HDL. ModelSim SE 6.4 has been used for Simulation. Input is given using PC’s Serial Port and the results are verified using MATLAB. The project basically consists of four major modules. Source Coding and Modulation at Transmitter end and Demodulation and Source Decoding at Receiver end. Source coding module consists of Scrambling, Reed Solomon Encoding, Convolutional Encoding and interleaving. Modulation includes PAM Mapping, Inverse Discrete Cosine Transform and constant envelope modulation. Demodulation includes Constant envelope demodulation, Discrete Cosine Transform and PAM Demapping. Source Decoding includes Deinterleaving, Viterbi Decoding, Reed Solomon Decoding and Descrambling.