A Model Based on Poisson Point Process for Analyzing MIMO Heterogeneous Networks Utilizing Fractional Frequency Reuse

In this paper, we propose a tractable and flexible model for K-tier multiple-input-multiple-output (MIMO) heterogeneous networks (HetNets), with the fractional frequency reuse (FFR) technique, based on the spatial Poisson point process (PPP). The MIMO HetNets consist of K tiers of base stations (BSs), where each tier may differ in terms of the transmit power, the BSs' deployment density, the target signal-to-interference ratio, the number of antennas, and the MIMO technique. Since HetNets experience serious cross-tier interference, FFR, as an interference management technique, is found as a suitable solution. Due to the randomness of the BSs' locations, the PPP is more and more used to model them in HetNets. In this paper, we use different independent PPPs to model the BSs' locations of each tier, and we take different MIMO techniques into consideration. We focus on two main types of FFR techniques, i.e., strict FFR and soft frequency reuse, and we derive the coverage probability expressions of cell-edge users (the users at the cell edge). We also derive the average rate expressions and show the impact of the main parameters on the coverage probability under closed-access and open-access cases.