Implementation of OFDM baseband transceiver with dynamic spectrum access for cognitive radio systems

VLSI architecture for OFDM baseband transceiver is developed, which is dedicated to cognitive radio systems. To facilitate dynamic spectrum access, this transceiver architecture employs a specialized FFT/IFFT module and a mapping/demapping module. Efficient mechanisms to omit input/ output of unused subcarriers are introduced. Also, calculation of spectrum intensity for subcarrier level carrier sensing is successfully integrated to the FFT module. Whole transmitter/ receiver modules are implemented by keeping compatibility with IEEE 802.11g. A prototype system is constructed by using Xilinx Virtex-II FPGA, which can transmit video sequence in real time.