Research And Design Of FFT Processor For MIMO-OFDM Applications

With the rapid development of mobile communication and wireless technology,higher demands for information transmission rate and information quality are booming. MIMO-OFDM technique,which combines the superiorities of OFDM and MIMO technologies to greatly increase the channel capacity,enhance the link throughput and reliability,and effectively resist channel frequency selective fading ,has been employed in the physical layer specification of the emerging IEEE 802.16e standard to provide wireless broadband access services.FFT processor,one of the key modules in MIMO-OFDM system, is utilized to modulate the data symbols in each subcarrier and implement the OFDM modulation.The algorithm adopted in FFT processor and the hardware implement scheme directly affect the chip performance and cost of MIMO-OFDM system.In this paper,we present a novel 256-point FFT/IFFT processor for the applications in IEEE 802.16e based on MIMO-OFDM.The pipeline FFT architecture is proposed to efficiently deal with 4 multiple data sequences and increase the throughput.Firstly,after analyzing and comparing various FFT algorithms and traditional FFT processor structures,we choose radix 4 decimation in frequency Cooley-Tukey FFT algorithm to realize the FFT processor,and propose a novel FFT architecture by taking advantage of the pipeline architecture combined partly parallel processing technology so as to achieve high throughput and low power dissipation .Secondly,the detailed desigh and optimization of FFT processor system are carried on,including butterfly processing unit,memory,data reordering unit,address generator,controller unit,etc.Finally,we realize the processor with RTL lever,and synthesize the FFT processor after the system functions are verified to correct.The design is synthesized in Design Compiler with TSMC 0.13μm CMOS technology. The maximum operating frequency is 123MHz.The Core size is 2.16mm2, inclding memory.At the operation clock rate of 64MHz,the effective throughput of proposed processor achieve 82.9Mbps meeting IEEE 802.16e requirements.The latency is 260 colck cycle.The results of verification and synthesise show that the proposed FFT processor satisfy the need for the applications in IEEE 802.16e based on MIMO-OFDM.