Spectrum sharing in ad hoc networks with antenna diversity

Two spectrum underlay schemes are studied for spectrum sharing of primary and secondary ad hoc networks. Each receiving node is equipped with multiple antennas and maximal ratio combining is used to exploit the antenna diversity. The first scheme allows the nodes to transmit freely, whereas the second scheme applies an exclusive region around the primary receiving node and prevents secondary nodes inside the region from transmission. For the two schemes, the aggregate interference is analyzed from stochastic geometry theory and the successful probability of transmission is derived. Moreover, the effects of the number of receiver antennas, the radius of the exclusive region, and the density of nodes on the transmission capacity are analyzed. Performance analysis indicates that under a fixed primary outage constraint, the radius of PERs is independent of the secondary transmission capacity. The antenna diversity benefits both primary and secondary networks.