Abstract
The multi-tier heterogeneous network (HetNet) architecture can potentially address the massive connectivity and high throughput demands of the emerging fifth generation (5G) of wireless networks. However, the inter-tier interference in HetNets is considered to be a major performance bottleneck. This paper proposes a geometry-based three-dimensional (3-D) stochastic channel model for the spatial characterization of the sum interference in a two-tier HetNet with small cells in tier-1 overlaid with massive multiple-input-multiple-output equipped macro-cell base stations in tier-2. The angular spreads of the interference and the desired signals are analyzed by using the theory of 3-D multipath shape-factors and analytical expressions are derived for their second-order fading statistics, viz: level-crossing-rate (LCR), average-fade-duration (AFD), spatial autocovariance, and the coherence distance. Further, analytical expressions to investigate the second-order fading statistics against signal-to-interference ratio are also derived. The validation of the derived analytical expressions is established through a comparison with computer-based simulations. To provide insights into the network sum interference mechanism, the LCR and AFD expressions are derived for the special case when the rate of fluctuation of the desired signal is much higher than that of the interference signal and vice versa. Furthermore, the impact of the model’s physical parameters, such as the link distance and the receiver’s direction of motion as well as the fading distribution parameters such as its intensity and shape factors on the fading statistics of the interference are evaluated. These results demonstrate that the elevation angle has a significant impact on the interference characterization in HetNet architectures such that it cannot be ignored in modeling emerging 5G communication scenarios.
Highlights
C ELLULAR networks are evolving from planned macrocell clusters to dense irregularly deployed multi-tier heterogeneous networks (HetNets) in which the macro-cells co-exist with small cells (SCs) such as pico- and/or femtocells
The simplification of a realistic propagation environment from 3-D to 2-D offers the advantage of mathematical tractability, it is of immense importance to model propagation channels in 3-D space for the emerging HetNet architectures that are envisioned to use large-scale planar antenna arrays at the macro-cell BSs (MBSs) and small coverage areas of their SCs coupled with base station (BS) heights that are significantly lower than that of surrounding building structures
A novel model for the 3-D angular characterization of the cumulative interference was proposed in a two-tier heterogeneous network with small cells in tier-1 overlaid with massive-multiple-input multiple-out (MIMO) equipped macro-cell BSs in tier-2
Summary
C ELLULAR networks are evolving from planned macrocell clusters to dense irregularly deployed multi-tier heterogeneous networks (HetNets) in which the macro-cells co-exist with small cells (SCs) such as pico- and/or femtocells. The work in [12] proposed a 2-D radio propagation model to characterize the network interference in the angular domain; the authors derived analytical expressions for the second order fading statistics of the signal-to-interference ratio (SIR). The simplification of a realistic propagation environment from 3-D to 2-D offers the advantage of mathematical tractability, it is of immense importance to model propagation channels in 3-D space for the emerging HetNet architectures that are envisioned to use large-scale planar antenna arrays at the MBSs and small coverage areas of their SCs coupled with BS heights that are significantly lower than that of surrounding building structures For these reasons it is imperative to develop 3-D analytical models for characterizing the sum co-channel interference in the angular domain for HetNet architectures in emerging 5G communication networks.
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