A software-defined radio based cognitive radio demonstration over FM band

In this paper, we present a software-defined radio (SDR) based cognitive radio (CR) implementation and demonstration over the frequency modulation (FM) band. Using GNU Radio as the software platform and USRP (Universal Software Radio Peripheral) SDR boards as the hardware solution, we implement and demonstrate a CR that autonomously senses the entire FM band, detects all the active FM stations (occupied bands) as well as the spectrum holes (non-occupied bands), exploits the available spectrum holes to transmit secondary users' data without interference with the existing FM transmission. Moreover, we demonstrate that when a primary user's transmission returns to its allocated spectrum band after a period of absence, the CR automatically adapts its transmission and hands off to a different spectrum hole that is available to avoid interference with the returning primary user. Moreover, we have proposed, implemented, and demonstrated a frequency hopping scheme over multiple spectrum holes to Support multiple secondary users while attaining the minimum interference among the users. Copyright (C) 2009 John Wiley & Sons, Ltd.