Cognitive radio universal software hardware

Abstract

The FPGA is an integral component of a software defined radio (SDR), which provides the needed reconfigurability for dynamically adapting its transceiver and data processing functions. The current state of the art in SDR design relies on complete processing of the raw samples at the host computer, thereby impacting time critical tasks. Instead, we propose to move the processing closer to the front-end by interfacing an external FPGA board with the SDR. Our architecture, called CRUSH, is composed of a Xilinx ML605 FPGA Development Board connected to an Ettus Research USRP N210 through an HDL framework, with a custom interface to allow flexible data transfer between them and independent programming capability on the two devices. Our test scenario for spectrum sensing, a key step in determining channel availability before transmission in dynamic spectrum access networks, indicates significant benefits: CRUSH can implement FFTs at 100× improvement, and can perform a complete sensing cycle 10× faster than legacy SDRs for large FFT sizes that enable wideband sensing. By potentially reducing the load on the host, and allowing a powerful FPGA extension for off the shelf devices, CRUSH will enable advances in both protocol design and radio hardware. For DySPAN we will show a live demonstration of the CRUSH platform performing spectrum sensing. For this demo CRUSH will be receive only and operate in the 50 MHz to 2.2 GHz region. A laptop will be connected to CRUSH via Ethernet and will display the live results via a MATLAB GUI.