Outage Performance of Cognitive-Radio Relay System based on the Spectrum-Sharing Environment

In the spectrum sharing systems, an unlicensed (secondary) user may share a frequency band with its licensed (primary) user as long as its transmission does not interfere with the primary user's communications. For the cognitive wireless relay networks, this interference regulation from the primary user may affect its cooperative scheme. In this paper, we investigate the outage performance of cognitive wireless relay networks in a spectrum sharing environment, in which the secondary users including the source and relays may take advantage of a frequency band of the primary user to transmit data to the receiver while not interfering with the primary user's communication. In particular, we quantify the relation between the outage performance of the secondary relay link and the interference inflicted on the primary user.