  In this paper, we investigate the problem of cooperative relay in CR networks
for further enhanced network performance. In particular, we focus on the two
representative cooperative relay strategies, and develop optimal spectrum
sensing and $p$-Persistent CSMA for spectrum access. Then, we study the problem
of cooperative relay in CR networks for video streaming. We incorporate
interference alignment to allow transmitters collaboratively send encoded
signals to all CR users. In the cases of a single licensed channel and multiple
licensed channels with channel bonding, we develop an optimal distributed
algorithm with proven convergence and convergence speed. In the case of
multiple channels without channel bonding, we develop a greedy algorithm with
bounded performance.
