In this paper we present a mean-field hardcore model of interference in wireless networks using CSMA. We consider d-regular random graph ensembles in which the edges are drawn randomly and an edge in a graph represents hard-core interaction such that the two nodes connected by the edge cannot be simultaneously active, or transmitting. We present an analysis of average activity in the presence of hard-core interactions in conflict graphs sampled from regular random graph ensembles. We also present experimental data obtained using Monte-Carlo simulations. A surprising conclusion of experimental results is that the average activity is not always monotonic in d. © 2015 IEEE.