Analysis of Coverage in Heterogeneous Cellular Networks

In this letter, we study the coverage of base stations (BSs) in heterogeneous cellular networks, where BSs with different transmit powers are randomly deployed. Specifically, the boundary of coverage is formulated analytically as the intersection of circles when a multiplicative bias is applied for BS association. Moreover, the effect of the transmit power and the path loss exponent on the coverage is investigated. Furthermore, for femto BSs with low transmit powers which are deployed to offload the traffic of the cellular system, it is shown that the expected number of offloaded users is concave with respect to the transmit power. Finally, the coverage of BSs is evaluated through simulations, which verify the accuracy of the presented analysis.