Coverage Analysis for CoMP in Two-Tier HetNets With Nonuniformly Deployed Femtocells

This letter investigates the coverage probability for coordinated multipoint transmission in a downlink two-tier heterogeneous network composed of macro base stations (BSs) and femto BSs, where the femto BSs are nonuniformly distributed. We propose a multicell cooperation scheme to improve the coverage performance of users located outside a prescribed distance from any macro BSs, which are defined as macrocell edge users (MEUs) in this letter. An expression for the coverage probability of a randomly located user is obtained. Numerical results are selected to verify the accuracy of the analytical results as well as to compare the performance of the proposed scheme with that of the traditional maximum-received-power association scheme. The curves show that the proposed scheme can enhance the MEUs´ coverage by about 5% when the received signal power from the nearest femto BS is comparable with the one from the nearest macro BS.