Sensoriamento Espectral por Detecção da Diferença de Fase Aplicado em Cenários de TVWS

Abstract

In Brazil, the National Telecommunications Agency (ANATEL) adopts a fixed spectrum allocation policy, assigning specific frequency bands for licensed user transmissions. For television broadcasts, the VHF (Very High Frequency) and UHF (Ultra High Frequency) bands are employed. However, these bands are often underutilized, resulting in spectral inefficiency and giving rise to the so-called TV White Spaces (TVWS). To address this issue, spectrum sensing (SS), implemented through cognitive radios (CRs), emerges as a viable solution. In this study, two SS techniques are explored: a robust method based on Cosine Feature Recognition Detection (CRD), which relies on the phase difference (PD) distribution of the received signal, and the conventional Energy Detection (ED) approach. Both techniques are evaluated under severe Rayleigh fading conditions, impulsive noise (IN), and noise uncertainty (NU), considering transmissions within the Brazilian TV bands. Licensed users in these bands employ the OFDM (Orthogonal Frequency Division Multiplexing) standard, specifically the ISDB-TB (Integrated Services Digital Broadcasting – Terrestrial Brazilian Version) signal. Simulation results indicate that the CRD technique achieves near-perfect detection performance in the presence of IN and excellent performance under NU, while the ED method exhibits significant performance degradation under these adverse conditions. These findings provide valuable insights into the trade-offs between detection complexity and robustness, contributing to the development of more reliable SS systems for cognitive radio networks.