Redes Cooperativas Cognitivas Multi-Usuario com Compartilhamento Espectral

Abstract

In this paper, the outage performance of cooperative cognitive networks with multiple relays amplify-and-forward (AF) is investigated. In our analysis, it is assumed that the secondary network is composed by one source node that communicates with one out of L destinations through a direct link and also via the help of one out of N AF relays. The selected secondary destination employs a selection combining technique for choosing the best link (direct or dual-hop link) from the secondary source. Considering an underlay spectrum sharing approach, the secondary communication is performed taking into account an interference constraint, where the overall transmit power is governed by the interference at the primary receiver as well as by the maximum transmission power available at the respective nodes. A closed-form expression for the outage probability is derived and validated by Monte Carlo simulations. Also, an asymptotic analysis is carried out and reveals that the diversity order of the considered system is not affected by the interference, and equals to L + N.