Coverage Analysis of Cognitive mmWave Networks with Directional Sensing

Due to a reduced level of interference, there may be many spatial and temporal opportunities available in mmWave networks for spectrum sharing in various forms, including cognitive communication. In this paper, we develop an analytical framework to study the gains of cognitive communication in mmWave networks with directional sensing. We consider a network consisting of one primary transmitter-receiver pair and multiple secondary transmitter-receiver pairs. To avoid any degradation to the primary link, the network imposes a transmission restriction on the secondary transmitter that limits its interference at the primary receiver. Due to directional sensing, the secondary activity depends on both the distance and orientation of the secondary links from the primary receiver. We first derive the medium access probabilities of the secondary transmitters to gain insights on the increment in transmission opportunities due to directional beamforming. We then derive the coverage of primary and secondary links. Using these results, we characterize the impact of secondary transmission on the primary link and the feasibility of secondary communication. We provide various design insights via numerical results.