# Performance Analysis of Ultra-Dense Networks with Elevated Base Stations

## TL;DR

This paper investigates the downlink performance of ultra-dense networks with elevated base stations, revealing that increased density and height can negatively impact coverage and efficiency due to complex propagation effects.

## Contribution

It introduces a dual-slope pathloss model with LOS probability and demonstrates the detrimental effects of BS height on ultra-dense network performance using stochastic geometry.

## Key findings

- Coverage probability decreases to zero with increasing BS density
- Area spectral efficiency also diminishes as BS density grows
- Elevated BS height negatively impacts system performance even with simple pathloss models

## Abstract

This paper analyzes the downlink performance of ultra-dense networks with elevated base stations (BSs). We consider a general dual-slope pathloss model with distance-dependent probability of line-of-sight (LOS) transmission between BSs and receivers. Specifically, we consider the scenario where each link may be obstructed by randomly placed buildings. Using tools from stochastic geometry, we show that both coverage probability and area spectral efficiency decay to zero as the BS density grows large. Interestingly, we show that the BS height alone has a detrimental effect on the system performance even when the standard single-slope pathloss model is adopted.