Outage performance of causal cognitive radio Z-interference fading channel with cognitive relaying

In this paper, we analyze the outage performance of causal cognitive radio Z-interference fading channel where cognitive user transmits concurrently with primary transmission while ensuring no degradation in primary's outage performance. Cognitive relay with best channel gain to primary receiver is selected from the set of qualified neighboring inactive cognitive users to relay primary's message. Analytical and simulations results show that cognitive relaying leads to improved outage mutual information and additional diversity for primary receiver while achieving significant outage mutual information for cognitive user.