Exploiting Temporal Secondary Access Opportunities in Radar Spectrum

In this paper, we quantify the temporal opportunities for secondary access to radar spectrum. Secondary users are assumed to be WLANs which opportunistically share the radar frequency band under the constraint that the aggregate interference does not harm radar operation. Each WLAN device employs dynamic frequency selection (DFS) as a mechanis m to protect the radar from the interference. We also consider an advanced interference protection mechanism, which is termed temporal DFS. It explo its the temporal variat ion of interference power due to the periodic rotation of radar antenna. It is observed that the probability of accessing the radar spectrum is significantly higher when the temporal DFS is used compared to the conventional DFS. As a consequence, more W LANs can 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 to radar band, and thus improve the spectrum utilization.