Capacity analysis of multicast transmission schemes in a spectrum-sharing scenario

In this study, the authors consider the asymptotic capacity of wireless multicast and unicast transmission schemes in a spectrum-sharing system. In these schemes, a secondary access point (SAP) utilises the licensed spectrum of an active primary user (PU) to send a common information to multiple secondary users simultaneously, as long as the interference power inflicted on the PU is less than a predefined threshold. At the SAP, interference channel-state information between the SAP and the PU is used to calculate the maximum allowable SAP transmit power to limit the interference. The authors derive the average capacity of these schemes based on extreme value theory. From the derived asymptotic capacities, the insights to the capacity behaviour can be drawn.