On the Sharing Opportunities of Ultra-Dense Networks in the Radar Bands

In this paper, we propose and evaluate regulatory policies that would improve sharing conditions/opportunities for indoor/outdoor ultra-dense networks to the radar bands where the demand actually is (i.e. hot spots and urban areas). We consider three regulatory policies: area power regulation, area deployment regulation and the combination of both of them. We address the scenario where the ultra-dense network share the spectrum with a rotating radar by means of geo-location databases and spectrum sensing that enables prior knowledge of the radar characteristics. Thus, secondary users can reliably exploit time and space domain sharing opportunities in the SBand and Ku-Band. We evaluate these opportunities in terms of the required time-averaged separation distance r̄H between the primary victim and the secondary transmitter in the hot zone (dense urban area) that guarantees a minimum secondary transmission probability, TXmin. Our results showed that adjacent channel sharing opportunities in the S-Band can be exploited in urban areas with relative small separation distances, which are further reduced if combined regulation is applied (less than 10 km for very high network density). Instead it is not feasible to exploit indoor and outdoor co-channel sharing opportunities in S-Band for cities close-by the radar even if regulation is applied. In the Ku-Band, the impact of interference aggregation is much less critical so exploitation of indoor sharing opportunities in urban areas close-by the radar is feasible even if no regulation was applied. For the outdoor case, adjacent channel sharing opportunities can be fully exploited without regulation and blind co-channel deployment of the secondary users if any of the proposed regulatory policies is applied. Overall, applying Area Deployment Regulation has the strongest impact on the reduction of the required separation distance, especially for homogeneous environment.