Diseño e implementación de un sistema de radio cognitiva para comunicación en la banda UHF.

Abstract

The current research was aimed to design and implement a cognitive radio system through Universal Software Radio Peripheral devices (USRP) and digital television equipment for communication in the ultra-high frequency band (UHF). The system is made up of two stages: the spectrum sensing stage is in charge of identifying the presence or absence of primary users (PU), and in turn, determining the free channel to establish communication, and the other stage carries out the transmission and reception simulating the secondary user (SU). The algorithm was developed on the LabVIEW platform, and it is based on the energy detection mechanism where the average power of the video carrier of the TV signal is calculated, and it is compared with the established threshold value. Once the sensing was carried out, the free channel is determined, and its center frequency is assigned for the transmission of the secondary user, who synchronizes the receiver to the same frequency using a local variable. It is necessary to mention that for the operational tests, a modulator and a digital terrestrial television (DTT) receiver were used, which simulate the primary user. After the system detects the channel's occupation, it releases the frequency and assigns another free frequency. Several tests were carried out to determine the system's response time, obtaining 1.07 and 41.47 seconds with shorter and longer response times, respectively. Also, through a sampling, an average response time of 21.33 seconds was obtained, allowing to verify the operation and the effectiveness in the change of frequency so that the system is efficient for numerous applications addressed at work.