Contribuições à análise de desempenho de protocolos de múltiplo acesso em sistemas de rádios cognitivos

Abstract

Cognitive Radio is a new concept in the development of wireless communication systems, enabling a more efficient use of radio spectrum and, therefore, it is a strong candidate as a technological solution for the future wireless networks by exploiting the frequency bands in an opportunistic fashion. In this environment, multiple access protocols have great impact on the performance of wireless communication networks and they play an important role in organizing different kinds of users to effectively access broadcast channels and avoid or make the interference acceptable in the primary network. In this work, we are able to analyze cognitive radios network performance in terms of throughput and average delay, considering Slotted Aloha and Carrier Sense Multiple Access (CSMA) protocols. In this study, the results that are presented previously in the literature are extended in order to consider the impacts of the capture effect and packet error rate on the networks performance. Finally, a new model is proposed to calculate the average delay for the cognitive radios network when the CSMA protocol is used.