Temporal secondary access opportunities for WLAN in radar bands

In this paper we quantify the temporal opportunities for secondary access in radar bands. Secondary users are assumed to be WLANs which opportunistically access the radar spectrum. Each WLAN device employs dynamic frequency selection (DFS) as a mechanism to protect the radar from interference. We also consider an advanced interference protection mechanism, which is termed temporal DFS. It exploits the temporal variation of interference power due to the rotation of radar antenna. It is observed that the probability of accessing the radar band is significantly higher when the temporal DFS is used compared to the conventional DFS. As a consequence, more WLANs utilize the radar spectrum when the temporal DFS mechanism is considered. This shows that having better knowledge of the primary user activity can bring about the increased opportunity of secondary spectrum access, and thus improve the spectrum utilization.