Smart Radio Challenge Final Report Spectrum Access for First Responders
Peiman Amini, Ehsan Azarnasab, Salam Akoum, Xuehong Mao, Harsha L. Rao · 2007
The issue of spectrum access is the single greatest obstacle in the development of a wireless network geared towards first responders. First responders need to effectively and reliably communicate with each other to provide help for the people in need. Smart radios or cognitive radios present themselves as strong candidates for the future of emergency communications. From a user’s perspective, a cognitive radio network should operate identically to a standard wireless network. However, cognitive radio nodes are designed to be “aware” of the other users of the spectrum, and avoid interfering with these users. A cognitive radio network is built to coexist in a given portion of the spectrum with the legacy devices to which the spectrum is assigned. We use Filterbanks for spectrum sensing and we show that this method exhibits superior performance in terms of the spectral dynamic range when compared to the conventional Fast Fourier Transform (FFT) techniques. We perform packet detection and channel equalization using a cyclic preamble. A fractionally spaced equalizer is used for both channel and timing recovery. The different processing tasks are divided between a TI c64x+ DSP and a XILINX Virtex IV FPGA. An ARM9 core is used for interfacing and running the Greenhills operating system. This report covers the cognitive radio modem components that we have implemented on the Small Form Factor (SFF) Software Defined Radio (SDR) platform, and the theory behind their design. It summarizes the work we have achieved throughout the phase II of the 2007 Smart Radio Challenge.