Novel DDS-Based Method to Realize OFDM Baseband Signals

In this paper, we propose a novel Orthogonal Frequency Division Multiplexing (OFDM) baseband signal generator to substitute the traditional Inverse Fast Fourier Transform (IFFT) based structure in an OFDM transmitter. In our architecture, we employ the Direct Digital Synthesizer (DDS) method to generate digital sub-carriers and transform frequency domain data to time domain. By making full use of the OFDM signal's two distinctive properties, we simplified the proposed architecture to the extent that multipliers can be discarded, and the DDS modules can share a small number of read-only memory (ROM) banks. Moreover, the proposed architecture has no latency while outputting the first time domain data, which leads to a quicker response compared to conventional structure. Finally, we conduct experiments on Field Programmable Gate Array (FPGA) which demonstrates that our DDS-based architecture saves more than half of the hardware resources and doubles the achievable frequency compared with traditional structure.