How Does Beamforming Influence the Connectivity of Cognitive Radio Ad-Hoc Networks?

In this paper, we investigate the impact of using directional antennas and beamforming schemes on the connectivity of cognitive radio ad-hoc networks (CRAHNs). Specifically, considering that secondary users uses two kinds of directional antennas, i.e. uniform linear array (ULA) and uniform circular array (UCA) antennas, and two different beamforming schemes, i.e. randomized beamforming and center-directed to communicate with each other, we study the connectivity of all combination pairs of directional antennas and beamforming schemes and compare their performances to those of omnidirectional antenna. The results obtained in this paper show that compared with omnidirectional transmission, beamforming transmission only benefits the connectivity when the density of secondary user is moderate. Moreover, the combination of UCA and randomized beamforming scheme gives the highest path connectivity. Finally, the number of antenna elements of directional antennas greatly affects path connectivity in CRAHNs.