Cognitive radio is an evolving wireless technology employed to increase the frequency spectrum utilization of the limited spectral resources. Cooperative communications has been established as a potential method of solving the fading effects in wireless communications, improving the reliability of network performance, network throughput, and adaptability. The cooperative diversity is achieved by using 2-hop decode amplify and forward (DAF) and 3-hop decode and forward (DF) and amplify and forward (AF) relaying protocols in cognitive radio network. The data is encoded by using Alamuti space...