Design and implementation of FFT/IFFT in IEEE 802.16d OFDM system

The IEEE 802.16 standard specifies the air interface of wireless metropolitan area network (WMAN), and aims to provide wireless broadband access for integrated voice and video services. This paper presents the efficient design and implementation of fast Frouier transform (FFT) and inverse fast Frouier transform (IFFT) for the application in IEEE 802.16d orthogonal frequency division multiplexing (OFDM) system. In this design, a novel pipeline structure for the branch of butterfly unit (BU) is proposed, which can improve the processing symbol rate by adding the number of branch flexibly. The symmetrical ping-pang structure of random access memory (RAM) is performed to increase the system throughput. Simulation results reveal that only with 1 branch of BU, the proposed FFT/IFFT design can almost achieve the maximum bandwidth requirement of IEEE 802.16d OFDM system. And this design has been verified by FPGA and successfully implemented in the prototype of WiMAX transceiver.