The integration of NOMA and Cognitive Radio seems like an interesting topic, since both can benefit from each other. In the spectrum sharing phase, for example, NOMA can help CR in scheduling secondary users.
Our team is focusing now on NOMA for Wi-Fi networks. We try to modify the Wi-Fi standard so that it has NOMA capabilities. We test our solutions in real network prototype using SDRs. There are already some papers about our results, but the study is still ongoing, so more are coming soon.
Merging NOMA with Other recent technologies like Cognitive radio, cooperative communication, machine learning, visible light communication, OTFS is in trend.