# On the Performance of Multi-tier Heterogeneous Cellular Networks with Idle Mode Capability

## TL;DR

This paper analyzes how idle mode capability in base stations affects the performance of multi-tier dense heterogeneous cellular networks, revealing significant improvements in coverage and efficiency, especially when BS density exceeds UE density.

## Contribution

It provides a practical analysis considering finite UEs, deriving association probabilities, active BS densities, and showing the positive impact of IMC on network performance, which differs from prior infinite-UE models.

## Key findings

- IMC significantly improves coverage probability and ASE.
- Surplus BSs occur when BS density exceeds UE density.
- Coverage and ASE increase with IMC application.

## Abstract

This paper studies the impact of the base station (BS) idle mode capability (IMC) on the network performance of multi-tier and dense heterogeneous cellular networks (HCNs). Different from most existing works that investigated network scenarios with an infinite number of user equipments (UEs), we consider a more practical setup with a finite number of UEs in our analysis. More specifically, we derive the probability of which BS tier a typical UE should associate to and the expression of the activated BS density in each tier. Based on such results, analytical expressions for the coverage probability and the area spectral efficiency (ASE) in each tier are also obtained. The impact of the IMC on the performance of all BS tiers is shown to be significant. In particular, there will be a surplus of BSs when the BS density in each tier exceeds the UE density, and the overall coverage probability as well as the ASE continuously increase when the BS IMC is applied. Such finding is distinctively different from that in existing work. Thus, our result sheds new light on the design and deployment of the future 5G HCNs.